Hydrogenaudio Forums

Hydrogenaudio Forum => Validated News => Topic started by: jmvalin on 2010-11-16 01:56:08

Title: CELT 0.9.1 is out!
Post by: jmvalin on 2010-11-16 01:56:08
Hi,

I'd like to announce CELT version 0.9.1. There have been many quality enhancements since 0.8.x and even more so since the last version announced on HA. You can get it from the CELT website (http://celt-codec.org/). Also, CELT is now a component of the Opus codec, which is in the process of being standardized by the IETF as a lossy audio codec for interactive applications.

Also, for those who would like to help, we are looking for volunteers to help tune the codec. The bit-stream is (finally) about to be frozen, so any quality improvements we can get before then is useful. No highly specialized skills required, just good critical listening abilities. As a first round, I'd be interested in comments and rankings of the following four audio files:

fileA.wav (http://jmvalin.ca/misc_stuff/fileA.wav)
fileB.wav (http://jmvalin.ca/misc_stuff/fileB.wav)
fileC.wav (http://jmvalin.ca/misc_stuff/fileC.wav)
fileD.wav (http://jmvalin.ca/misc_stuff/fileD.wav)

The bit-rate is fairly low (64 kb/s), so artefacts are easy to hear. This is the original (uncompressed) file (http://jmvalin.ca/misc_stuff/compare/comp.wav). I'm interested in a quality ranking of all these four files (especially the ones that sound similar). I'll reveal the contents of these files after people have responded.
Title: CELT 0.9.1 is out!
Post by: punkrockdude on 2010-11-19 18:18:45
I think, after several listenings, that A sounds best at the 16th note hi-hat part. The other ones sound like the the attacks are deteriorating. I usually think of mp3 and aac as smearing audio at lower bitrates and codecs like ogg is deteriorating. I am sorry but I can't explain the ogg/Celt sound with any better word. I am looking forward how this codec is going to sound! Regards
Title: CELT 0.9.1 is out!
Post by: Primius on 2010-11-19 23:21:49
In file A i noticed warbling distortion on guitars but less smearing of transients compared to B,C and D.

B,C and D sounded equal to me.
Title: CELT 0.9.1 is out!
Post by: IgorC on 2010-11-21 01:25:35
(http://img217.imageshack.us/img217/1994/celta.png)

logs h*tp://www.mediafire.com/?7ed142tcipntet1
Title: CELT 0.9.1 is out!
Post by: jmvalin on 2010-11-21 02:45:28
Thanks very much guys. I guess I should start by telling you what these files were. So fileA was Vorbis at 64 kb/s, while fileB, fileC and fileD were all CELT at 64 kb/s. The only difference between B, C and D was in the bit allocation. B was the default (at the time), while C and D were experimental variations. I have since been able to do further improvements, which should greatly reduce the issues on the transients. I'm now curious to have opinions on the following four

fileH.wav (http://jmvalin.ca/misc_stuff/fileH.wav)
fileI.wav (http://jmvalin.ca/misc_stuff/fileI.wav)
fileJ.wav (http://jmvalin.ca/misc_stuff/fileJ.wav)
fileK.wav (http://jmvalin.ca/misc_stuff/fileK.wav)

How do you think these compare to fileA and fileB? What are the artefacts that still stand out?
Title: CELT 0.9.1 is out!
Post by: IgorC on 2010-11-22 19:32:38
(http://img263.imageshack.us/img263/4939/celttest2.png)

logs h*tp://www.mediafire.com/?t8ko84f34bz8b5f

The results are surprisingly good for codec with very low delay. It's better than Vorbis and should be comparable to HE-AAC.
Title: CELT 0.9.1 is out!
Post by: jmvalin on 2010-11-23 01:16:40
(http://img263.imageshack.us/img263/4939/celttest2.png)

The results are surprisingly good for codec with very low delay. It's better than Vorbis and should be comparable to HE-AAC.


Hi IgorC,

Thanks for much again. Essentially, fileH is derived from fileB, but gives more bits to high frequencies and less to low/mid. From there, I/J/K are different attempt at intensity stereo, so your comparison on those is very useful. I'll try and take that into account to figure out the best way to do intensity stereo properly. In the mean time I actually found a bug in testK.wav. Could you see if fileL.wav (http://jmvalin.ca/misc_stuff/fileL.wav) is any better?
Title: CELT 0.9.1 is out!
Post by: IgorC on 2010-11-23 02:38:49
All right, I will test fileL later.

There was an IS test of Nero AAC encoder some time ago. It might be useful (or not) to take a look at samples. http://www.hydrogenaudio.org/forums/index....showtopic=40022 (http://www.hydrogenaudio.org/forums/index.php?showtopic=40022)

A few words about my test conditions. The headphones Sennheiser HD 447. Some people didn't find it great but I think it's matter of right position on the head. I have Soundcard Audigy SE 24/96 on my desktop but listening test  isn't great with it because of noise of PC cooler (despite is enough quite). So I perform tests on laptop with onboard soundcard Realtek HD audio 24bits / 192 kHz. I find that it is actually better. Tests are performed in deep silence, no hurry at all and with good mood.
I think it's good enough for 64 kbps test.
Title: CELT 0.9.1 is out!
Post by: IgorC on 2010-11-23 03:20:01
Thanks for much again. Essentially, fileH is derived from fileB, but gives more bits to high frequencies and less to low/mid. From there, I/J/K are different attempt at intensity stereo, so your comparison on those is very useful. I'll try and take that into account to figure out the best way to do intensity stereo properly. In the mean time I actually found a bug in testK.wav. Could you see if fileL.wav (http://jmvalin.ca/misc_stuff/fileL.wav) is any better?


What file(s) (A,B...) you want to compare fileL to?
Title: CELT 0.9.1 is out!
Post by: jmvalin on 2010-11-23 04:19:26
Thanks for much again. Essentially, fileH is derived from fileB, but gives more bits to high frequencies and less to low/mid. From there, I/J/K are different attempt at intensity stereo, so your comparison on those is very useful. I'll try and take that into account to figure out the best way to do intensity stereo properly. In the mean time I actually found a bug in testK.wav. Could you see if fileL.wav (http://jmvalin.ca/misc_stuff/fileL.wav) is any better?


What file(s) (A,B...) you want to compare fileL to?


Comparing to H, K and I would be most useful.
Title: CELT 0.9.1 is out!
Post by: IgorC on 2010-11-27 03:51:36
(http://img269.imageshack.us/img269/2827/celt3.png)

Sample I is still preferable but there is no statistical difference.
Title: CELT 0.9.1 is out!
Post by: IgorC on 2010-11-28 04:00:35
Description of artifacts.
1st sample.  Samples H and I present the wavy distortion on strings. Does it call warbling?
2d sample. Sample L presents a bit more hissing than others (on tom drums).
3d sample. All sample present hissing.

2d and 3d sample. Well it's rather like water sprinkling artifacts than hissing.

5th. H sample presents low frequency echo.
6th. Sample K did quite bad on speech.
Title: CELT 0.9.1 is out!
Post by: jmvalin on 2010-12-08 14:29:06
Thanks again for taking the time to listen to those files. I think I've been able to further improve the bit allocation and intensity stereo. I thought you'd be curious to hear the current version (http://jmvalin.ca/misc_stuff/fileU.wav) compared to both Vorbis (http://jmvalin.ca/misc_stuff/fileA.wav) and HE-AAC (http://jmvalin.ca/misc_stuff/comp_he.wav).
Title: CELT 0.9.1 is out!
Post by: IgorC on 2010-12-08 19:37:30
What encoders did you used for Vorbis and HE-AAC?
Since you test VBR I can encode with very high quality encoders. Vorbis Aotuv and Apple HE-AAC. Both VBR.

It will be interesting to see how CELT will handle difficult samples like fatboy http://www.hydrogenaudio.org/forums/index....mode=linearplus (http://www.hydrogenaudio.org/forums/index.php?showtopic=19682&mode=linearplus)
Title: CELT 0.9.1 is out!
Post by: jmvalin on 2010-12-09 01:25:38
What encoders did you used for Vorbis and HE-AAC?
Since you test VBR I can encode with very high quality encoders. Vorbis Aotuv and Apple HE-AAC. Both VBR.

It will be interesting to see how CELT will handle difficult samples like fatboy http://www.hydrogenaudio.org/forums/index....mode=linearplus (http://www.hydrogenaudio.org/forums/index.php?showtopic=19682&mode=linearplus)


For Vorbis, I have used version 1.2 (according to Monty, 1.3 would do exactly the same) but I have not tried aoTuV. For HE-AAC, I used the latest version of the Nero encoder. All files are VBR. Also, I forgot to mention that I also tried HE-AAC v2, but it sounded much worse than v1 at that rate so I didn't post it.

Regarding the fatboy sample, here's what it sounds like with CELT at 64 kb/s (http://jmvalin.ca/misc_stuff/fatboy_celt64.wav). I resampled the original to 48 kHz because CELT is mostly optimised for 48 kHz (it can handle 44.1, but I haven't tuned it much recently). So here's the 48 kHz reference (http://jmvalin.ca/misc_stuff/fatboy48.wav). I haven't actually listened to it yet, but I'll do so shortly. Note that there's a few clipped samples (both in the resampled original and in the coded version), so maybe slightly reducing the gain could help (I didn't do that). So let me know what you think.
Title: CELT 0.9.1 is out!
Post by: jmvalin on 2010-12-09 01:36:07
Regarding the fatboy sample, here's what it sounds like with CELT at 64 kb/s (http://jmvalin.ca/misc_stuff/fatboy_celt64.wav). I resampled the original to 48 kHz because CELT is mostly optimised for 48 kHz (it can handle 44.1, but I haven't tuned it much recently). So here's the 48 kHz reference (http://jmvalin.ca/misc_stuff/fatboy48.wav). I haven't actually listened to it yet, but I'll do so shortly. Note that there's a few clipped samples (both in the resampled original and in the coded version), so maybe slightly reducing the gain could help (I didn't do that). So let me know what you think.


OK, just listened to it and it indeed sounds *really* bad. I suspect this could actually be a bug in my code because this is not the type of artefact that CELT normally produces. I'll look into it. Thanks for pointing this sample to me.
Title: CELT 0.9.1 is out!
Post by: IgorC on 2010-12-09 02:51:00
Chris has made tremendous work on compilation of  the samples those cause different types of distortion.
http://www.hydrogenaudio.org/forums/index....st&p=695576 (http://www.hydrogenaudio.org/forums/index.php?s=&showtopic=77584&view=findpost&p=695576)
http://www.hydrogenaudio.org/forums/index....st&p=696090 (http://www.hydrogenaudio.org/forums/index.php?s=&showtopic=77584&view=findpost&p=696090)
http://www.hydrogenaudio.org/forums/index....st&p=696266 (http://www.hydrogenaudio.org/forums/index.php?s=&showtopic=77584&view=findpost&p=696266)

CELT has intensity stereo and some samples with rich stereo can be worth to test. Like http://ff123.net/samples/SinceAlways.flac (http://ff123.net/samples/SinceAlways.flac) and http://www.hydrogenaudio.org/forums/index....ost&id=5661 (http://www.hydrogenaudio.org/forums/index.php?act=attach&type=post&id=5661)

But if you wish we can stick with your samples.

I will make some blind tests with sampleU vs Vorbis vs HE-AAC v1 today and tomorrow.
Title: CELT 0.9.1 is out!
Post by: IgorC on 2010-12-09 04:07:57
(http://img217.imageshack.us/img217/9521/celttest4.png)

Logs h*tp://www.mediafire.com/?c54du2c2b95mjsn

Mainly CELT made good except spanish guitar. And acoustic drums part (67-75 seconds) has a low frequency echo. Woman's  voice part wasn't great.

I've tried your sample fatboy_celt64.wav vs Aotuv 5.7 -q0.0 (64 kbps) vs Nero 1.5.4 -q0.25 (64 kbps).
Aotuv 5.7 did very well because it went too high (107 kbps). It has an unrestricted VBR.
Quote
ABC/HR Version 1.1 beta 2, 18 June 2004
Testname:

1R = D:\Samples\fatboy\aotuv 5.7 fatboy_30sec.wav
2R = D:\Samples\fatboy\fatboy_celt64.wav
3R = D:\Samples\fatboy\nero 64 fatboy_30sec.wav

---------------------------------------
General Comments:

---------------------------------------
1R File: D:\Samples\fatboy\aotuv 5.7 fatboy_30sec.wav
1R Rating: 4.5
1R Comment:
---------------------------------------
2R File: D:\Samples\fatboy\fatboy_celt64.wav
2R Rating: 2.0
2R Comment:
---------------------------------------
3R File: D:\Samples\fatboy\nero 64 fatboy_30sec.wav
3R Rating: 2.0
3R Comment:
---------------------------------------
ABX Results:
Title: CELT 0.9.1 is out!
Post by: jmvalin on 2010-12-09 05:01:40
Chris has made tremendous work on compilation of  the samples those cause different types of distortion.
http://www.hydrogenaudio.org/forums/index....st&p=695576 (http://www.hydrogenaudio.org/forums/index.php?s=&showtopic=77584&view=findpost&p=695576)
http://www.hydrogenaudio.org/forums/index....st&p=696090 (http://www.hydrogenaudio.org/forums/index.php?s=&showtopic=77584&view=findpost&p=696090)
http://www.hydrogenaudio.org/forums/index....st&p=696266 (http://www.hydrogenaudio.org/forums/index.php?s=&showtopic=77584&view=findpost&p=696266)

CELT has intensity stereo and some samples with rich stereo can be worth to test. Like http://ff123.net/samples/SinceAlways.flac (http://ff123.net/samples/SinceAlways.flac) and http://www.hydrogenaudio.org/forums/index....ost&id=5661 (http://www.hydrogenaudio.org/forums/index.php?act=attach&type=post&id=5661)

But if you wish we can stick with your samples.

I will make some blind tests with sampleU vs Vorbis vs HE-AAC v1 today and tomorrow.


Actually, I'll try the samples you're pointing to. I at least want to make sure CELT doesn't completely break down in a way similar to the fatboy sample. On that one I have traced the problem to an encoder-size issue with the transient detector. The CELT transient analysis is still pretty simple and currently doesn't handle the case of two transient within the same 20 ms. I'm working on fixing that.

As for the stereo samples, here's Herbie_Hancock_celt64.wav (http://jmvalin.ca/misc_stuff/Herbie_Hancock_celt64.wav) and SinceAlways_celt64.wav (http://jmvalin.ca/misc_stuff/SinceAlways_celt64.wav). Let me know what you think of those.
Title: CELT 0.9.1 is out!
Post by: jmvalin on 2010-12-09 13:47:22
Thanks again for the results. I'll investigate a bit on the 5th sample to see why CELT does much worse than HE-AAC. Regarding fatboy, here's the result of a transient detector hack (http://jmvalin.ca/misc_stuff/fatboy_celt64b.wav) that gives an idea of how things should sound once I manage to fix the transient analysis. For now my hack is just just consider every single frame as a transient.
Title: CELT 0.9.1 is out!
Post by: jmvalin on 2010-12-09 20:31:47
Thanks again for the results. I'll investigate a bit on the 5th sample to see why CELT does much worse than HE-AAC. Regarding fatboy, here's the result of a transient detector hack (http://jmvalin.ca/misc_stuff/fatboy_celt64b.wav) that gives an idea of how things should sound once I manage to fix the transient analysis. For now my hack is just just consider every single frame as a transient.


OK, I think I managed to fix my transient detector code. Here's how it sounds with the new transient detector (http://jmvalin.ca/misc_stuff/fatboy_celt64c.wav). Unlike the previous sample, there is no longer any "cheating" involved. Now I just need to make sure that I haven't broken other samples. I don't think I have, but I'd be curious to have your comparative opinion on:

fileU.wav (http://jmvalin.ca/misc_stuff/fileU.wav)
fileX.wav (http://jmvalin.ca/misc_stuff/fileX.wav)
fileY.wav (http://jmvalin.ca/misc_stuff/fileY.wav)

After that I'll look into other problem samples.
Title: CELT 0.9.1 is out!
Post by: IgorC on 2010-12-10 03:30:35
(http://img819.imageshack.us/img819/3912/celttest5.png)
Sample X did better on speech but still has low freq echo on wood-sound drums.
Oh and I encoded Vorbis with Aotuv 5.7 -q0. Nothing changes.

Now looking into Fatboy and the rest of samples....

Fatboy
Code: [Select]
ABC/HR Version 1.1 beta 2, 18 June 2004
Testname:

1R = D:\Samples\fatboy\Apple 64 HEAAC CVBR fatboy_30sec.wav
2R = D:\Samples\fatboy\fatboy_celt64c.wav
3L = D:\Samples\fatboy\nero 64 fatboy_30sec.wav
4R = D:\Samples\fatboy\aotuv 5.7 fatboy_30sec.wav

---------------------------------------
General Comments:

---------------------------------------
1R File: D:\Samples\fatboy\Apple 64 HEAAC CVBR fatboy_30sec.wav
1R Rating: 2.0
1R Comment:
---------------------------------------
2R File: D:\Samples\fatboy\fatboy_celt64c.wav
2R Rating: 4.0
2R Comment:
---------------------------------------
3L File: D:\Samples\fatboy\nero 64 fatboy_30sec.wav
3L Rating: 2.2
3L Comment:
---------------------------------------
4R File: D:\Samples\fatboy\aotuv 5.7 fatboy_30sec.wav
4R Rating: 4.5
4R Comment:
---------------------------------------
ABX Results:


CELT did transparent on Since Always.
Code: [Select]
ABC/HR Version 1.1 beta 2, 18 June 2004
Testname:

1R = D:\Samples\Herbien hancokc and Since alwyas\Nueva carpeta\SinceAlways_celt64.wav
2L = D:\Samples\Herbien hancokc and Since alwyas\Nueva carpeta\nero 64 kbps SinceAlways.wav
3R = D:\Samples\Herbien hancokc and Since alwyas\Nueva carpeta\apple 64 HEAAC CVBR SinceAlways.wav
4R = D:\Samples\Herbien hancokc and Since alwyas\Nueva carpeta\aotuv 5.7 SinceAlways.wav

---------------------------------------
General Comments:

---------------------------------------
2L File: D:\Samples\Herbien hancokc and Since alwyas\Nueva carpeta\nero 64 kbps SinceAlways.wav
2L Rating: 1.7
2L Comment:
---------------------------------------
3R File: D:\Samples\Herbien hancokc and Since alwyas\Nueva carpeta\apple 64 HEAAC CVBR SinceAlways.wav
3R Rating: 2.8
3R Comment:
---------------------------------------
4R File: D:\Samples\Herbien hancokc and Since alwyas\Nueva carpeta\aotuv 5.7 SinceAlways.wav
4R Rating: 4.7
4R Comment:
---------------------------------------
ABX Results:



CELT did very well on Hancock too.
Code: [Select]
ABC/HR Version 1.1 beta 2, 18 June 2004
Testname:

1R = D:\Samples\Herbien hancokc and Since alwyas\nero q025 64 kbps Herbie_Hancock.wav
2R = D:\Samples\Herbien hancokc and Since alwyas\aotuv 5.7 Herbie_Hancock.wav
3R = D:\Samples\Herbien hancokc and Since alwyas\Herbie_Hancock_celt64.wav
4R = D:\Samples\Herbien hancokc and Since alwyas\apple 64 heaac cvbr Herbie_Hancock.wav

---------------------------------------
General Comments:

---------------------------------------
1R File: D:\Samples\Herbien hancokc and Since alwyas\nero q025 64 kbps Herbie_Hancock.wav
1R Rating: 3.8
1R Comment: left channel noise
---------------------------------------
2R File: D:\Samples\Herbien hancokc and Since alwyas\aotuv 5.7 Herbie_Hancock.wav
2R Rating: 3.2
2R Comment: distortion on trumpet
---------------------------------------
3R File: D:\Samples\Herbien hancokc and Since alwyas\Herbie_Hancock_celt64.wav
3R Rating: 4.3
3R Comment:
---------------------------------------
4R File: D:\Samples\Herbien hancokc and Since alwyas\apple 64 heaac cvbr Herbie_Hancock.wav
4R Rating: 2.7
4R Comment: intermitent noise in left channel
---------------------------------------
ABX Results:
Title: CELT 0.9.1 is out!
Post by: jmvalin on 2010-12-10 14:38:57
Wow, thanks very much for all these results. I'm glad to see that I managed to fix the quality on fatboy without making the other cases worse. Also nice to see that the rich stereo samples didn't cause problems either, though I think they weren't too bad for intensity stereo because there's a lot of pan, but the image itself isn't that wide.
Title: CELT 0.9.1 is out!
Post by: SebastianG on 2010-12-10 15:10:41
Hi Jean-Marc,

I just skimmed through some parts of the source code and noticed in vq.c the "scrambling" (exprotation1 etc). It looks like this is roughly equivalent to an all-pass filter. Since you apply this on the spectral coefficients and due to the time/frequency duality this is equivalent to a time-dependent frequency shift within a frame. I know the original motivation for this processing (reducing metallic artefacts) and it seems to be doing what it's supposed to but it sure is an odd thing to do. On the downside you smear strong tonal components over a larger spectrum which kind of defeats the purpose of an MDCT in terms of energy compaction w.r.t. tonal components (MDCT as opposed to, say, a PQMF with fewer subbands). Maybe this is why the guitar sample doesn't work that well... The encoded coefficients correspond to some kind of chirps (due to the time-dependent frequency shift) and not a windowed cosine. Have you checked the impulse response of a single one surrounded by zeros in X followed by inverse exprotation + inverse MDCT? Might be interesting to see what it looks like...

...just wanted to share this perspective...

Cheers and congrats for the impressive 64kbps performance!
SG
Title: CELT 0.9.1 is out!
Post by: IgorC on 2010-12-10 18:01:39
Jean-Marc,

How does CELT scale with higher bitrate 80-128 kbps?
HE-AAC has good quality/size trade at 48-64 kbps but already no advantage over LC-AAC at 80 kbps.  While Vorbis vice versa.
Title: CELT 0.9.1 is out!
Post by: jmvalin on 2010-12-10 18:25:07
How does CELT scale with higher bitrate 80-128 kbps?
HE-AAC has good quality/size trade at 48-64 kbps but already no advantage over LC-AAC at 80 kbps.  While Vorbis vice versa.


CELT was originally designed as a low-delay high-bitrate codec. It's only recently that I've been able to make it listenable around 64 kb/s. I've encoded the usual test file at 80 kb/s and 128 kb/s:

comp_celt80.wav (http://jmvalin.ca/misc_stuff/comp_celt80.wav)
comp_celt128.wav (http://jmvalin.ca/misc_stuff/comp_celt128.wav)

Let me know what you think of those. One of my goals is to scale to very high/transparent quality as well.
Title: CELT 0.9.1 is out!
Post by: jmvalin on 2010-12-10 18:34:26
I just skimmed through some parts of the source code and noticed in vq.c the "scrambling" (exprotation1 etc). It looks like this is roughly equivalent to an all-pass filter. Since you apply this on the spectral coefficients and due to the time/frequency duality this is equivalent to a time-dependent frequency shift within a frame. I know the original motivation for this processing (reducing metallic artefacts) and it seems to be doing what it's supposed to but it sure is an odd thing to do. On the downside you smear strong tonal components over a larger spectrum which kind of defeats the purpose of an MDCT in terms of energy compaction w.r.t. tonal components (MDCT as opposed to, say, a PQMF with fewer subbands). Maybe this is why the guitar sample doesn't work that well... The encoded coefficients correspond to some kind of chirps (due to the time-dependent frequency shift) and not a windowed cosine. Have you checked the impulse response of a single one surrounded by zeros in X followed by inverse exprotation + inverse MDCT? Might be interesting to see what it looks like...


Hi Sebastian,

Actually, the spreading in vq.c is not equivalent to an all-pass filter. It's a non-linear operation (when viewed from a time-domain signal) because it actually creates frequency content that wouldn't be there otherwise. The idea is to avoid "birdie artefacts", aka musical noise. One thing to note is that the amount of spreading depends on two things: 1) the bit-rate (less spreading as the bitrate goes up), and 2) a global per-frame parameter. It's possible with the current bit-stream to use no spreading at all. In fact, there's a (still a bit simple) function that decides how much spreading to apply based on how tonal the audio is. That being said, I think the importance of the spreading has probably gone down recently since we're no longer allowing codebooks of just one pulse. In any case, you can hear the difference and decide for yourself what the effect is:

with spreading (http://jmvalin.ca/misc_stuff/fileZ.wav)
without spreading (http://jmvalin.ca/misc_stuff/fileZ_nospread.wav)

What do you think?
Title: CELT 0.9.1 is out!
Post by: SebastianG on 2010-12-10 19:40:59

I just skimmed through some parts of the source code and noticed in vq.c the "scrambling" (exprotation1 etc). It looks like this is roughly equivalent to an all-pass filter. Since you apply this on the spectral coefficients and due to the time/frequency duality this is equivalent to a time-dependent frequency shift within a frame. [...]

Actually, the spreading in vq.c is not equivalent to an all-pass filter. It's a non-linear operation (when viewed from a time-domain signal) because it actually creates frequency content that wouldn't be there otherwise.

This is not a contradiction to what I tried to say, though. Let me try to reword it. exprotation1 takes a vector and some parameters and maps it to another one (in-place). What I'm saying is that this is a convolution (ignoring the boundaries). It's shift-invariant (frequency-invariant if you will) and it's linear after all. Consider the implications. Convolving in the frequency domain = multiplication in time. And this multiplication in time shifts frequencies. The filter's "group delay" in the frequency domain equals the frequency shift in the time domain. The filter likely has a varying group delay, so the frequency shift varies over time -- possibly very quickly.

The idea is to avoid "birdie artefacts", aka musical noise. One thing to note is that the amount of spreading depends on two things: 1) the bit-rate (less spreading as the bitrate goes up), and 2) a global per-frame parameter.
[...]
What do you think?

I get the idea. If I remember correctly, we talked about this 1-2 years ago. But I didn't know exactly what kind of rotations you apply until now. I was just surprized to see you implemented a mapping that is linear and shift-invariant. Hence, the comment. But I get the idea. I would have probably tried pseudo-random rotations first (within small groups of coefficients, like 32 or so) because I consider this to be the equivalent of dithering in a gain/shape coding approach. As such, it should be well-suited for encoding noisy parts without "birdie artefacts" and without introducing extra energy (which is hard to avoid with "normal" dithering). But this shift-invariant linear mapping seems to be doing its job as well.
Title: CELT 0.9.1 is out!
Post by: jmvalin on 2010-12-10 19:48:38
I get the idea. If I remember correctly, we talked about this 1-2 years ago. But I didn't know exactly what kind of rotations you apply until now. I was just surprized to see you implemented a mapping that is linear and shift-invariant. Hence, the comment. But I get the idea. I would have probably tried pseudo-random rotations first (within small groups of coefficients, like 32 or so) because I consider this to be the equivalent of dithering in a gain/shape coding approach. As such, it should be well-suited to encode noisy parts without "birdie artefacts" and without introducing extra energy (which is hard to avoid with "normal" dithering). But this shift-invariant linear mapping seems to be doing its job as well.


Actually, the "random rotation" approach was the first thing I tried and it didn't work well, at least not unless you use a very large number of rotation (leading to high complexity). What I'm using not is rotations by angles that are close to 90 degrees. In fact, the less spreading I want, the closer I am to 90 degrees (rather than 0 degrees). It's not intuitive, but that's what I found to work best so far.
Title: CELT 0.9.1 is out!
Post by: jmvalin on 2010-12-10 22:36:24
OK, so I've worked a bit on improving some of the samples like the Spanish guitar and the blocks. The problem with the blocks is that I can't actually hear the artefact, but given your description I still think I know what it is. Can you give me your opinion on:

fileZ.wav (http://jmvalin.ca/misc_stuff/fileZ.wav)
fileAA.wav (http://jmvalin.ca/misc_stuff/fileAA.wav)
fileAD.wav (http://jmvalin.ca/misc_stuff/fileAD.wav) (added)

Let me know if it fixes the problem for you without introducing other artefacts. Oh, and if you want to save download time, I also have the flac version (just change the extension).
Title: CELT 0.9.1 is out!
Post by: IgorC on 2010-12-13 21:01:44
Jean-Marc,

What do you plan for test of CELT?  If you aren't hurry I will have some spare time after 21st of December and be glad to make much more blind tests.
Do you also consider to make more large test that will involve more people and/or more samples or release some sort of preview version of codec?
I guess if there will be binaries later then probably more people will look into it and report.

Thank you.
Title: CELT 0.9.1 is out!
Post by: jmvalin on 2010-12-13 21:25:47
What do you plan for test of CELT?  If you aren't hurry I will have some spare time after 21st of December and be glad to make much more blind tests.
Do you also consider to make more large test that will involve more people and/or more samples or release some sort of preview version of codec?
I guess if there will be binaries later then probably more people will look into it and report.


The plan right now is to do a "tentative freeze" (i.e. frozen unless something bad comes up) of the bit-stream in early January and then do more formal testing with many listeners. Until then, I'm tuning as much as I can based on informal listening by people like you. Just so you know, your help so far has been very useful and has helped me improve many aspects of CELT. You can just compare the latest sample to fileB.wav (last released version) to see just how much progress was made.
Title: CELT 0.9.1 is out!
Post by: IgorC on 2010-12-23 23:34:37
Jean-Marc,

I see that version 0.10.0 has been released. Let me know If you want to resume listening tests.
I got a new pair of Sennheiser HD650 and my previous lovely HD447 (planning to get decent amp in january). I'm still adapting to new headphones but it could be interesting to see the results.

Have read Monty's article about CELT. http://people.xiph.org/~xiphmont/demo/celt/demo.html (http://people.xiph.org/~xiphmont/demo/celt/demo.html)
Glad to see high performance. 
Title: CELT 0.9.1 is out!
Post by: NullC on 2010-12-24 01:02:05
Jean-Marc,

I see that version 0.10.0 has been released. Let me know If you want to resume listening tests.
I got a new pair of Sennheiser HD650 and my previous lovely HD447 (planning to get decent amp in january). I'm still adapting to new headphones but it could be interesting to see the results.

Have read Monty's article about CELT. http://people.xiph.org/~xiphmont/demo/celt/demo.html (http://people.xiph.org/~xiphmont/demo/celt/demo.html)
Glad to see high performance. 



It would be very helpful if you could listen to
http://jmvalin.ca/misc_stuff/old_layout.flac (http://jmvalin.ca/misc_stuff/old_layout.flac)
http://jmvalin.ca/misc_stuff/new_layout2.flac (http://jmvalin.ca/misc_stuff/new_layout2.flac)
http://jmvalin.ca/misc_stuff/new_layout5.flac (http://jmvalin.ca/misc_stuff/new_layout5.flac)

We're working on using a slightly different band structure in order to scale better to very high bitrates, but we're concerned with harming the quality at low rates.
Title: CELT 0.9.1 is out!
Post by: IgorC on 2010-12-24 18:35:21
The differences are small.
The results with HD650
(http://img153.imageshack.us/img153/605/celt6newvsoldlayouts.png)


ABC/HR logs+comments h*tp://www.mediafire.com/?o2x0saix4ocxbdt

I found that guitar samples are boring me as their artifacts are less or more the same and my profile of listener isn't quite similar with acoustic guitar. However there were killer samples of ac. guitar that could be good to try http://www.hydrogenaudio.org/forums/index....ost&id=5462 (http://www.hydrogenaudio.org/forums/index.php?act=attach&type=post&id=5462). Can you change those guitar samples with it or something else?
You can ask me about how sound drums, percussions, rock/metal drive guitars (rhythm and solo), some classic instruments like viol/violin family, trumpets.

Some previously tested samples:
Linchpin http://www.hydrogenaudio.org/forums/index....st&p=682220 (http://www.hydrogenaudio.org/forums/index.php?s=&showtopic=77994&view=findpost&p=682220)
Girl http://www.hydrogenaudio.org/forums/index....st&p=683378 (http://www.hydrogenaudio.org/forums/index.php?s=&showtopic=77994&view=findpost&p=683378)
Fatboy?
http://ff123.net/samples/Waiting.flac (http://ff123.net/samples/Waiting.flac)
Creuza http://www.hydrogenaudio.org/forums/index....ost&id=2069 (http://www.hydrogenaudio.org/forums/index.php?act=attach&type=post&id=2069)
Title: CELT 0.9.1 is out!
Post by: C.R.Helmrich on 2010-12-25 20:23:04
Fatboy?

http://www.hydrogenaudio.org/forums/index....showtopic=19682 (http://www.hydrogenaudio.org/forums/index.php?showtopic=19682)

Chris
Title: CELT 0.9.1 is out!
Post by: IgorC on 2010-12-26 03:32:27
Hi, Chris.

Actually the question was about the possibility to test the sample.
Anyway thank you for pointing out.

Title: CELT 0.9.1 is out!
Post by: IgorC on 2010-12-26 08:39:15
I think it can be worth to redo the last test or do another with another samples? What do you think?
I've experimented with new headphones. Yes, it wasn't time for experiments but I get a new position (angle and distance) of headphones that give balanced and more natural sound (to my taste). Previously the headphones were positioned a little bit tight and high frequencies were somewhat attenuated.
The old results shouldn't be wrong but maybe different. In fact it can be useful to perform new test with new position because the listeners wear headphones or put the speakers in different ways.
This time I will perform full ABX (not just ABC/HR) between old vs new 2, new 2 vs new 5, new5 vs old layouts. The results will be here on Tuesday.
Title: CELT 0.9.1 is out!
Post by: IgorC on 2010-12-29 22:26:34
I've tried several time with HD650 and HD447. The samples aren't transparent but no statistical difference between them.
If you need test something more let me know.
Title: CELT 0.9.1 is out!
Post by: IgorC on 2010-12-30 19:55:49
Aparently CELT scales good with higher bitrates.

CELT 0.10.0 vs Aotuv at 96 kbps:
http://downloads.xiph.org/audio/demo/celt1...-0.10.0-96.flac (http://downloads.xiph.org/audio/demo/celt1/celt-0.10.0-96.flac)
headphones HD650
(http://img408.imageshack.us/img408/3383/test7celtvsvorbisat96kb.png)

ABX, ABC/HR + comments h*tp://www.mediafire.com/?tuc27jkhahjwesy
Title: CELT 0.9.1 is out!
Post by: jmvalin on 2010-12-31 04:34:03
Aparently CELT scales good with higher bitrates.

CELT 0.10.0 vs Aotuv at 96 kbps:
http://downloads.xiph.org/audio/demo/celt1...-0.10.0-96.flac (http://downloads.xiph.org/audio/demo/celt1/celt-0.10.0-96.flac)
headphones HD650
(http://img408.imageshack.us/img408/3383/test7celtvsvorbisat96kb.png)

ABX, ABC/HR + comments h*tp://www.mediafire.com/?tuc27jkhahjwesy


Thanks very much for these results. Testing higher rates is something I wanted to do for a while. What you're reporting is very good news. If you have time, it'd be interesting to also compare with the appropriate AAC profile (not sure which profile is best at that bitrate).

Also, do you have a way to actually build CELT from the source code? If so, it would be interesting if you can play around with it and see on what kind of files we should be trying to improve quality.
Title: CELT 0.9.1 is out!
Post by: IgorC on 2010-12-31 05:00:12
If you have time, it'd be interesting to also compare with the appropriate AAC profile (not sure which profile is best at that bitrate).

LC-AAC is far more suggested at 96 kbps by developers and listeners. From my previous tests I always prefer Apple LC-AAC encoder http://www.hydrogenaudio.org/forums/index....&pid=657232 (http://www.hydrogenaudio.org/forums/index.php?showtopic=74781&mode=threaded&pid=657232)
http://www.hydrogenaudio.org/forums/index....c=66949&hl= (http://www.hydrogenaudio.org/forums/index.php?showtopic=66949&hl=)
But now apple encoder has a bug (a reported one) at 80-96 kbps. The quality is affected.
I will try to find the older version free of bug and perform the test. itunes 9.0.0.70 had not this bug.

Also, do you have a way to actually build CELT from the source code? If so, it would be interesting if you can play around with it and see on what kind of files we should be trying to improve quality.

The only code I compile is for microcontrollers (fortunately it will change in next year). If anybody can compile it I will play with it.


P.S.  itunes 9.0.070 is found. Will post the results later.
Title: CELT 0.9.1 is out!
Post by: IgorC on 2010-12-31 07:43:12
96 kbps:
LC-AAC info: iTunes 9.0.0.70, 96 kbps, VBR, 44100 kHz. (48000 kHz isn't available for this bitrate).
(http://img801.imageshack.us/img801/1880/test8celtvslcaacappleat.png)

ABX logs h*tp://www.mediafire.com/?uwu1lqc7qd4vn7l

Apple encoder has produced 100 kbps file. But it's ok since it's VBR test. Second iTunes AAC has somewhat inferior settings while qtaacenc has access to higher quality options - --high and --tvbr (True VBR). But qtaacenc encoder doesn't work with older version that I downloaded to avoid the bug.

True vbr would produce the same quality but at slightly lower bitrate (2-3 kbps). So it's fair comparison.
Title: CELT 0.9.1 is out!
Post by: IgorC on 2010-12-31 17:44:42
Maybe CELT should compete not only with LD-AAC but also with enhanced extension of it (ELD-AAC). ELD-AAC has low-delay SBR and recently improved parametric stereo derived from MPEG surround standard. It makes ELD-AAC highly competitive at low bitrates.

In my opinion it's will be great to see if CELT will be on par with HE-AAC at low bitrates and LC-AAC at high bitrates. Now CELT is already comparabale with these codecs.

Plus new audio coding standard USAC is near to be complete. It brings improved tools like eSBR, MPEG surround, new entropy coder and efficient speech coding. So it's logical to think that all those tools will be optimized to be included to new revision of ELD.

Anyway I didn't see any ELD encoder that was available publicly. That's where comes CELT.
Title: CELT 0.9.1 is out!
Post by: rt87 on 2011-01-01 00:59:25
I wonder if someone can do 48kbps tests comparing with aotuv 5.7 and HE-AAC?
Title: CELT 0.9.1 is out!
Post by: IgorC on 2011-01-01 13:32:44
You can have an idea basing on results of 64 kbps test (look at post #22)
Title: CELT 0.9.1 is out!
Post by: NullC on 2011-01-26 01:09:23

Anyone following along with the CELT technical development may be interested in this updated I provided to the IETF codec working group today:

http://www.ietf.org/mail-archive/web/codec...t/msg02109.html (http://www.ietf.org/mail-archive/web/codec/current/msg02109.html)

Title: CELT 0.9.1 is out!
Post by: jmvalin on 2011-01-27 23:36:20
OK, so we've been a bit quiet lately but working hard towards freezing the bit-stream. Before we do that, I'd be interested in some feedback on the latest version. Can you compare the following two files:
Title: CELT 0.9.1 is out!
Post by: IgorC on 2011-01-28 13:48:21
The artifacts of both files have very similar nature. No matter  how many times I've tried and whatever technics (ABX or  ABXY) no difference was catched. While encoded files clearly present distortion comparing to source (comp.wav).
Title: CELT 0.9.1 is out!
Post by: jmvalin on 2011-01-29 05:24:11
The artifacts of both files have very similar nature. No matter  how many times I've tried and whatever technics (ABX or  ABXY) no difference was catched. While encoded files clearly present distortion comparing to source (comp.wav).


Thanks. That's actually good news. I mainly wanted to make sure that we didn't actually break anything.
Title: CELT 0.9.1 is out!
Post by: IgorC on 2011-02-05 01:50:10
0.11.0 has been released. Good news.

I wonder that there is still a little interest in CELT on this forum.
Apparently it has already better quality than Vorbis and it's open source alternative to HE-AAC/LC-AAC.
It can be good for internet radio, video streaming, archiving the audio with high quality as well.
Title: CELT 0.9.1 is out!
Post by: sauvage78 on 2011-02-05 03:54:09
Personnaly I have some interest in it, but I need a win32 command line encoder/decoder to test it my way. I am moderately interested in testing how it competes nowadays against aotuv & nero aac in a self-made single test, but I am not interested to help for development in the long run... specially if it doesn't compete well & specially on already encoded wavs which are not my own selection of killer samples. (In short I am interested in a very selfish test serving my own needs & I don't care what others may think of my test). Anyway I am not in a hurry to test it because if ever it would beat aotuv (which would mean it has improved a LOT since V0.52 ... which it certainly has considering how many updates there were since V0.52) then it will be frustrating to have all the aotuv zealots on my back for teaching them that Vorbis would likely be dead ... I wish that CELT would be the new messiah but having seen in the past how musepack/vorbis/aotuv development has stalled when their developer interest slowed down, I suspect that, sooner or later (hopefully later), CELT will follow the same fate, so honestly I am much more interested by an open source aac equivalent to x264 developed by a team, which I think would be more future proof, then I will ever be by a xiph codec developed by a loner (no matter how clever he is). My only problem with aac is its non-native & non-robust gapless support via tricky deletable tags. I like the robust vorbis gapless support & I think CELT might inherit this which is why I still have some interest in it. AAC already perfectly suits my needs for blu-ray audio part encoding because gaplessness is not needed there.
If ever CELT beats aotuv then we will end up with a better-then-vorbis codec with no [f2k-cuetools-eac3to-mkv-5.1-rockbox] support, which would be an annoying (but hopefully temporary) situation.

All this put together made that if I do have some interest in CELT, I always plan to test it ... later. I use flac for CD & nero aac for blu-ray & CELT alone is unlikey to change this. My small interest for CELT is due to 2 possibility both with unlikely probability:
1: I run out of HDD space because my 5 HDD sata (the 6th one is for SDD) are full, then I will need CELT. (Only if I don't favor lossywav)
2: Webm becomes better than x264, then I will need CELT. (... but I don't believe in Santa Claus anymore)

As you see CELT beeing trapped in the family of Xiph codecs, & this family of codec being non-competitive (x264 beat webm/theora, & nero aac beats aotuv), even if CELT alone would become the perfect lossy codec (the quality of nero aac with the robust gaplessness of vorbis) that doesn't mean it would be enougth for me to use it, because CELT is "bonded by blood" to a sub-optimal family of video codecs. (Using it would mean mixing mpeg with xiph in mkv which I tend to avoid.)

I know it may sound discouraging, but I only explain all that for you to understand why I didn't anwser to your request for me to test CELT one month ago.
Just like lossywav, I like CELT on paper, but I just don't use it in real life actually.

Sorry for not answering your pm directly a month ago (jmvalin), I was too lazy & short of time to write this down. Furthermore I was fearing that you wouldn't like much my opinion about the actual state of lossy codecs.

To sum up according to me, CELT is in a very paradoxal situation, where it might have become a real challenger for aotuv & nero aac, but because of its missing features/missing support/non-mpeg status, even if it would be the best codec around, I would likely not use it ... well at last not untill an eco-system was built around it.

I don't want to be the only guy on earth knowing that CELT is (maybe) the best pure lossy codec around, so I just don't test it to avoid the headache ... I know it's a vicious circle, but it's not my problem, I leave the frustration to ... IgorC [no you don't need to thks me, man ]
Title: CELT 0.9.1 is out!
Post by: jmvalin on 2011-02-05 04:20:28
A few things I'd like to say here about CELT to answer some of questions and address some misconceptions. First, CELT has gone a long, long way since 0.5.2. In fact, there were more changes since 0.5.2 than there were from the beginning to 0.5.2. Among the things that changed is that CELT now supports longer frame sizes than you tested earlier (20 ms vs 5 ms) though the smaller frame size is still supported. Another difference is that it now supports VBR. On top of that, there's been a huge number of other changes. I'm sure if you tested again, the results you would get would be a lot different than with 0.5.2. I recommend you listen to the samples on Monty's CELT demo page (http://people.xiph.org/~xiphmont/demo/celt/demo.html) (if you hear clicks in the samples when played from the web page, it's a browser bug and you should download them directly), which has some comparisons with Vorbis and AAC. The 32 kb/s and 48 kb/s samples aren't that useful (below the sweet spot), but the 64 kb/s ones should give a good idea of the quality. Of course, CELT also scales up to 510 kb/s for stereo.  Also, if you look at IgorC's results, you'll see that CELT actually beats Vorbis aotuv on most samples, though of course the results vary from one sample to another.

As for you comment about "As you see CELT beeing trapped in the family of Xiph codecs", you should know that CELT is actually one half of the Opus that is currently being standardized at the IETF. The other half is Skype's SILK codec. So practically speaking, CELT is likely to see very wide deployment, starting with Skype. As I've pointed out before, CELT's main focus is *interactive* audio, which means it can give very good audio quality for real-time applications (unlike MP3, Vorbis and HE-AAC). To achieve that we've had to do some sacrifices, but even despite that, the quality is competitive with that of the AAC family. And the same codec can actually work from 6 kb/s (speech) to 510 kb/s, rather than having different profiles for different bit-rates and applications (HEv1, HEv2, LC, LD, ELD). So being standardized at the IETF means we're no longer talking about just a single developer or organization.

As for the tools, don't worry, that's the next thing on the list once the bit-stream is frozen. Which brings up another point. The bit-stream is currently in soft-freeze, so there's a short window of time where the codec is in a pretty good state, but we can still fix any issue that would be discovered before the bit-stream is officially frozen. So I definitely recommend you try CELT again. If binaries are a problem, I may be able to get someone to make Win32 ones. Alternatively, I can provide you with encoded samples.
Title: CELT 0.9.1 is out!
Post by: sauvage78 on 2011-02-05 05:20:14
One of the reason why I wait for a CLI encoder/decoder to test CELT is because I have a pack of around 50 supposed killer samples that were uploaded by other ABXers on HA & that I need to test in order to know which one I can or cannot ABX personnaly. So actually I cannot really tell you what I will test or not (other than the samples I used in my first test). Before I would even start testing CELT there would be a first round of samples selection. Most likely I will test these 50 samples on aotuv 96-128Kbps & select those which are abnormally bad for the bitrate, only then will I test those samples on CELT. In the end I will only publish result for those I am 100% sure that I can ABX (A handfull). I am not the guy trying to ABX randomly selected average music on average bitrate, IMHO it is useless. I will stress the codec to the maximum.

Also I don't want to be tied to your release timing, in the past I already tried to help lossywav development & I stopped because each time I published some ABX results Nick.C instantly published a new lossywav version & it was a neverending game. (It was interesting in the beginning but it is tiring & I get bored in the end).
Nowaday I don't want to help any lossy codec for development as actually I simply don't use lossy anymore (except Nero aac for blu-ray).
If you release a CLI encoder/decoder, sooner or later, I will very likely test CELT by curiosity, but not because you asked me. This will happen naturally just because it is interesting to test how all lossy codecs evolved every year (or ... two years nowadays). So this is also one of the reason why I didn't test CELT again so far, both nero aac & aotuv development have been almost frozen since my test (there were only very minor update), & I think that except for CELT my old test results are still overall valid, which is why I haven't updated it. A multi-codec test with lot of code move is much more exciting than a single codec test, currently the lack of updates from competitors doesn't help to motivate me testing CELT.

Sorry, I don't really care if it would be the right time to test CELT just because there will be a bitstream freeze. Also I cannot promise that I will do it instantly as you releases binaries (in the past already I promised some listening test to Nick.C that I never did). ABXing is a boring task (specially if you don't use the codec yourself) & I will do it when I fell in the mood for it. All I can say is that if you would have regulary released binaries it's a long time I would already have re-tested it.

Sorry if it sound annoying, ABXing is just way more enjoyable for me, if it's independant & free.
Title: CELT 0.9.1 is out!
Post by: IgorC on 2011-02-05 05:34:46
Sorry if it sound annoying, ABXing is just way more enjoyable for me, if it's independant & free.


I can't disagree.
One should test on his own music. The music that you listen and only you can provide some interesting feedback on the music that you know how to listen.

Title: CELT 0.9.1 is out!
Post by: [JAZ] on 2011-02-05 10:40:46
@sauvage:

I don't understand you.
First, you put doubts on how much it has improved since 0.5.2, when there have been several threads with samples to test the progression.
Next, you say that you don't care, because you would like to test with your own samples, and for that you need an encoder/decoder.
Then, jmvalin corrects some misconceptions that you expressed and explains why you should expect a clear improvement since 0.5.2, if you cared.
And then, you insist that you don't have interest in it, because the codec has been a moving target, not like aotuv or nero aac.

Sincerely, I was going to get the source and try to compile either with mingw or visual studio (whatever was easier, since i haven't seen the sources yet), but your comments sort of discouraged me to do so.

You know.. its sort of going to a forum that talks about a beta of a program, and saying that you hate betas and don't trust the developers.
Title: CELT 0.9.1 is out!
Post by: jmvalin on 2011-02-05 11:53:31
Sorry if it sound annoying, ABXing is just way more enjoyable for me, if it's independant & free.


Well, you can do it any time you like. What I'm saying is that if it happens within the next month or so, then you can *also* have a potential impact on the codec. Though in fact even after, you could at least impact the encoder. IgorC's earlier testing was in that regard very very useful. Between him, Monty and a few others, I was able (in about 2-3 months) to increase the quality from clearly inferior to Vorbis to better than Vorbis on many/most samples.
Title: CELT 0.9.1 is out!
Post by: sauvage78 on 2011-02-05 12:28:08
Quote
you put doubts on how much it has improved since 0.5.2
? I have no doubt it has improved a lot, the problem is more did it improve so much that it is now on par with well established competitors ? ... sorry when it come to ABXing, the only guy I trust more than myself is /mnt (because I often agree with him on bad samples, & when I don't obviously ... it means he is more skilled than me), not that I don't trust other ABXer, but when you start ABXing for yourself, except for finding new killer samples easyly, you don't need the opinion of others anymore. IIRC, it happened that I already disagreed with IgorC about the relative quality of aotuv vs. nero aac in the past, so I take his results with caution, not that I would cast a shadow on him, but IIRC using a different methodology & different samples, he ended with a different conclusion than me (using other samples & methodology). Maybe he was right & maybe I would have agreed with him if I would have run the exact same test. Maybe he is more sensitive than me on some kind of artefact, I don't know. All I know is that I trust myself, as pretentious as it may sound, simply because it's me who will listen to my own encodes, & not the ABXer with golden ears which tells me that this codec is good or bad.

Quote
because the codec has been a moving target
? I don't care about the codec being a moving target, as long as you don't request me to run after it.

... well in case I wasn't clear, I am not some kind of philantropic guy wasting my time testing codecs just for fun, if I test codecs that's because I expect some personnal benefits from using them !!! In the past I have spent some time testing experimental codecs more or less as an audio enthousiast would do, just for fun. Years ago I tested CELT out of pure curiosity (back then it happened that it was very bad but it was very experimental so in fact I didn't even considered it as a competitor), but for various reasons this time is over for me. Not that I don't want to do ABXing anymore, but it has to be worth the effort. I have no doubt that CELT did improve a LOT (specially has I know how bad it was), but the overall state of lossy codecs is rather depressing IMHO as most well established codecs have stagnated since my old test. So what I am trying to explain is that actually my personnal gain for testing it is low as I am unlikely to use it (I admit that nowadays I am more a mpeg guy, not that I particulary like patents but sadly the quality of x264 & nero AAC speaks for itself, & I like the safety of the industry support to mpeg, I also admit that I completely changed my mind on this topic as when I started ABXing (Edit: Before I started) I was a vorbis fan). In the end, even when it may have seemed that I was randomly playing at ABXing experimental codecs, I had IMHO a big personnal gain from testing so many different lossy codecs: I have learned exactly what I expect from a lossy codec & I expect so much that sadly none of them fully pleases me & ... I use lossless. But don't think it's about quality, the quality of nero aac q0.55 (~192Kbps VBR) is enought for my taste: I don't use lossy because no lossy codecs has my 3 requirements: (1:Transparent Quality)+(2:Native Robust Gaplessness)+(3:Future Proof: Big Norm). Only lossywav can almost fullfill all my (quality+features) needs, but it's twice the HDD space ...

So to come back to CELT, yes I do have some interest in testing it, the biggest question for me being how close/far it will be from aotuv & if it is slowly friendly killing vorbis in the shadow ? Answering this question alone is interesting, even if the other codecs didn't evolve, but whatever is the answer in the end I may not use CELT personnaly so I don't care if I test it here & now. Maybe Vorbis will, but I won't die if I don't test CELT soon. I known I will re-test it sooner or later anyway, my goals & my timing are just not the same as jmvalin, he would like me to test CELT before he froze the bitstream, but I expect to test it slowly within 1 or 2 months after he releases a windows binarie. I just don't want to spoil my fun.

Anyway I wanted to apologize for not answering his invitation a month ago, which was cowardice.
Title: CELT 0.9.1 is out!
Post by: jmvalin on 2011-02-05 14:18:48
If you want to see how far CELT has come, there's no need to argue for hours about is. Here's CELT at 64 kb/s (http://downloads.xiph.org/audio/demo/celt1/celt-0.10.0-64.wav) and here's Vorbis at 64 kb/s (http://downloads.xiph.org/audio/demo/celt1/vorbis-64.wav). The original is here (http://downloads.xiph.org/audio/demo/celt1/comp48.wav).
Title: CELT 0.9.1 is out!
Post by: IgorC on 2011-02-05 17:39:04
If binaries are a problem, I may be able to get someone to make Win32 ones. Alternatively, I can provide you with encoded samples.

If there will be binaries than I will can do an extensive test on many samples  and make detailed conclusions as performance per genres, different kind of artifacts, stereo image, soundstage, comparison with other codecs. Or you can suggest what aspects are need to be tested.

If you think that celt is ready for this kind of test then binaries are good. However if you still need some results for particular samples than you can provide these samples as well.


PS.  It might also be true that comparison between CELT and Vobris, AAC at higher bitrates (128 kbps and above)  can be misleading. CELT has new superior technics but Vorbis and AAC encoders are very well tuned during the years.
Title: CELT 0.9.1 is out!
Post by: list on 2011-02-06 18:25:51
any future improve towards 32kbps range?
Title: CELT 0.9.1 is out!
Post by: jmvalin on 2011-02-07 03:00:44
any future improve towards 32kbps range?


It has improved a lot and will continue to improve. That being said, I doubt it'll reach what I consider acceptable quality level. For the record, I'm not aware of any codec that produces acceptable stereo music quality at 32 kb/s. The closest may be HE-AAC v2, but I still find the quality to be way too low to be acceptable.
Title: CELT 0.9.1 is out!
Post by: NullC on 2011-02-07 04:42:59
PS.  It might also be true that comparison between CELT and Vobris, AAC at higher bitrates (128 kbps and above)  can be misleading. CELT has new superior technics but Vorbis and AAC encoders are very well tuned during the years.


You can say that.  For example, the CELT encoder doesn't have an explicit psy-model. The format is designed so that one isn't strictly necessary, but a good one could be very helpful for VBR rate selection, right now all the VBR really does for CELT is improve transients.  We haven't included an explicit psy-model because we've been focused on things that can't be done after the bitstream is final. The encoder also doesn't perform any analysis which would increase latency or which would be too computationally expensive for embedded devices, e.g. it doesn't use anything more than 2.5ms lookahead and it doesn't switch frame sizes on the fly (except the binary short/long decision).  But future and alternative encoders can and will.

So there should be plenty of room for future improvements remaining.

Though I'm not so confident at comparisons with AAC and Vorbis at higher rates for another reason:  This is not at all what CELT was designed to do.  We built it for very low-latency, so that you could have awesome quality teleconferencing and telephony, remote music, low bandwidth digital microphones and headsets, etc.  By some happy accident it's looks like its almost competitive with the best popular high latency codecs at least at some bitrates.  But most implementations these codecs have the benefit of well tuned VBR engines, so on high rates with killer samples I expect that they'll do much better than CELT.

But you can not use AAC (non-LD) or Vorbis for telephony, it's a non-starter. They're useless for this.  Among the codecs that can be used for low latency CELT is very good. In strict hard-CBR mode (no-bitres) CELT is very good, etc.

If you care about audio quality, then you should care about CELT not because it's going to be the best hifi codec for storing your music collection (These days you're crazy if you're not just using lossless for that purposes) but because you're going to find it all around you for other purposes— embedded in telephones and teleconferencing systems and in VoIP apps, used for wireless audio systems, in video games for realtime audio as well as sound effects, etc.

In any case,  since people asked... I create a win32 build of the 0.11.0 encoder and decoder tools:  https://people.xiph.org/~greg/celt/celt011-win32.zip (https://people.xiph.org/~greg/celt/celt011-win32.zip)

I would encourage testing at 48kHz rather than 44.1kHz because 48kHz is our officially supported and tuned sampling rate. The other rates are offered on a best effort basis for custom applications which have particular timing requirements.  I'd certainly like to hear reports about other rates if you test them, but I can't promise that they work as well as 48kHz.
Title: CELT 0.9.1 is out!
Post by: jmvalin on 2011-02-07 04:53:31
I would encourage testing at 48kHz rather than 44.1kHz because 48kHz is our officially supported and tuned sampling rate. The other rates are offered on a best effort basis for custom applications which have particular timing requirements.  I'd certainly like to hear reports about other rates if you test them, but I can't promise that they work as well as 48kHz.


I'd like to add that the recommended frame size is 960 samples for 48 kHz sampling rate (i.e. 20 ms). That's going to be the default for the Opus codec. That being said, CELT will also support 44.1 kHz and other frame sizes.
Title: CELT 0.9.1 is out!
Post by: list on 2011-02-07 11:52:16
I found some samples in which @64 kbps,48 khz , CELT is giving much worse results than aotuv/nero.
like this one Bachpsichord.wv (http://www.rarewares.org/test_samples/Bachpsichord.wv)
I used a 0.10 celt binary i found. Maybe it's not the last one, but you can take a look anyway.
Title: CELT 0.9.1 is out!
Post by: jmvalin on 2011-02-07 12:03:37
I found some samples in which @64 kbps,48 khz , CELT is giving much worse results than aotuv/nero.
like this one Bachpsichord.wv (http://www.rarewares.org/test_samples/Bachpsichord.wv)
I used a 0.10 celt binary i found. Maybe it's not the last one, but you can take a look anyway.


Yes, that's a known "killer sample" for CELT. As I said, CELT now sounds better than Vorbis on many/most samples, but certainly not all of them. File samples like Bachpsichord, this is mostly due to some trade-offs we had to do to get low latency.
Title: CELT 0.9.1 is out!
Post by: NullC on 2011-02-07 15:30:56
I found some samples in which @64 kbps,48 khz , CELT is giving much worse results than aotuv/nero.
like this one Bachpsichord.wv (http://www.rarewares.org/test_samples/Bachpsichord.wv)
I used a 0.10 celt binary i found. Maybe it's not the last one, but you can take a look anyway.


Yes, that's a known "killer sample" for CELT. As I said, CELT now sounds better than Vorbis on many/most samples, but certainly not all of them. File samples like Bachpsichord, this is mostly due to some trade-offs we had to do to get low latency.


For the very tone rich samples that do poorly (mostly due to CELT's small transform size) I'm very interested in knowing if anyone encounters any that can't be fixed by throwing bitrate at them.  So long as the codec goes transparent at some semi-reasonable rate for these samples then VBR can eventually be made to cover it.  I don't expect anything to be found that doesn't eventually sound good, but if something is then having the opportunity to fix it in the bitstream would be very helpful.

Title: CELT 0.9.1 is out!
Post by: IgorC on 2011-02-09 09:26:54
I have a job to do until 10th of March. After that I will have a plenty time to explore CELT.
Title: CELT 0.9.1 is out!
Post by: IgorC on 2011-02-13 20:09:20
Very short test on difficult eig sample (http://www.hydrogenaudio.org/forums/index.php?showtopic=49601)

Big surprise is that CELT handles it very well  . Much better than HE-AAC and aotuv Vorbis last test beta

Results for 64 kbps:
CELT  4.0
Vorbis  3.5
Apple HE-AAC 2.5
Nero HE-AAC 2.0

Vorbis's bitrate went from nominal -q0 (~64 kbps) to 96 kbps while CELT performs better without desviation from established bitrate (65.393 kbps)
Nero also ends up at 77 kbps. But it doesn't help.

Code: [Select]
ABC/HR Version 1.1 beta 2, 18 June 2004
Testname:

1L = D:\Samples\celt011\eig\Nero 64 kbps q025 eig.wav
2L = D:\Samples\celt011\eig\Vobis beta.wav
3L = D:\Samples\celt011\eig\Apple CVBR 64 kbps High eig.wav
4R = D:\Samples\celt011\eig\eig_celt64.wav

---------------------------------------
General Comments:

---------------------------------------
1L File: D:\Samples\celt011\eig\Nero 64 kbps q025 eig.wav
1L Rating: 2.0
1L Comment: clicking
---------------------------------------
2L File: D:\Samples\celt011\eig\Vobis beta.wav
2L Rating: 3.5
2L Comment:
---------------------------------------
3L File: D:\Samples\celt011\eig\Apple CVBR 64 kbps High eig.wav
3L Rating: 2.5
3L Comment: clicking
---------------------------------------
4R File: D:\Samples\celt011\eig\eig_celt64.wav
4R Rating: 4.0
4R Comment:
---------------------------------------
ABX Results:

Tested with headphones  Sennheiser HD 650 and audio interface E-MU Tracker Pre USB 2.0

Log and test files h*tp://www.mediafire.com/?fdk216h5s89b121
Title: CELT 0.9.1 is out!
Post by: IgorC on 2011-02-13 22:37:55
Single result for one random sample.
Test of scalability of quality with bitrate.

Results:
kbps - mark:
64 - 2.0
96 - 3.5
128 - 4.3-4.5
192 - 5.0 (transparent)

It scales good and proof my rough rule of thumb that every +32 kbps diffscore is lower by factor of 2.

Log and test files www.mediafire.com/?e8ldh4urm3ymnn7
Title: CELT 0.9.1 is out!
Post by: IgorC on 2011-02-14 15:32:18
The first sample that wasn't transparent at 192 kbps (maybe at higher bitrate too). Linchpin (http://www.hydrogenaudio.org/forums/index.php?act=attach&type=post&id=4937)
The issue with this sample is that CELT adds some colored background noise to rhythm guitar. It's more obvious at lower bitrates. I didn't compare to other encoders because of lack of concentration at that point but I remember that it was a difficult sample always.

All previous and this sample were encoded and decoded with following settings:
Code: [Select]
celtenc --bitrate 192 --comp 10 -V --stereo l.wav l_192.oga
celtdec l_192.oga l_192_celt.wav


All samples were encoded at 44.1 kHz. I know that 48 khz would be preferable but I have very little time for resampling right now.

ABX log:
Code: [Select]
foo_abx 1.3.4 report
foobar2000 v1.1.2
2011/02/14 04:45:31

File A: D:\Samples\linchpin\Linchpin__Edit_.flac
File B: D:\Samples\celt011\l_192_celt.wav

04:45:31 : Test started.
04:46:20 : 01/01  50.0%
04:46:33 : 01/02  75.0%
04:46:45 : 02/03  50.0%
04:46:53 : 02/04  68.8%
04:47:06 : 03/05  50.0%
04:47:29 : 04/06  34.4%
04:47:50 : 05/07  22.7%
04:47:55 : 06/08  14.5%
04:48:15 : 07/09  9.0%
04:50:16 : 07/10  17.2%
04:50:34 : 08/11  11.3%
04:50:47 : 08/12  19.4%
04:51:09 : 09/13  13.3%
04:51:51 : 10/14  9.0%
04:52:31 : 11/15  5.9%
04:52:54 : 12/16  3.8%
04:53:01 : Test finished.

----------
Total: 12/16 (3.8%)
Title: CELT 0.9.1 is out!
Post by: IgorC on 2011-02-14 21:21:55
CELT performs not enough well and worse than Vorbis on creuza (http://www.hydrogenaudio.org/forums/index.php?act=attach&type=post&id=2069)
First of all I thought it was not optimal sample rate (44.1 kHz).  Then I resampled it to 48 kHz  (foobar built-in resampler with high quality mode) but strangely CELT performed even worse.

Logs and encoded files www.mediafire.com/?obhkrhhcoypcdbo

Big picture. CELT has no problem with electronic and rock music and it preserves the stereo and transients well.
Problem for CELT is sample like creuza, bittersweet (from my previous posts). These are tonality samples.
I report only where CELT performs suboptimal. On samples like Closer to God, Linchpin, Since Always, Girl, Waiting it performs at least on par and actually better than Vobis or AAC in the most of the cases.
Title: CELT 0.9.1 is out!
Post by: jmvalin on 2011-02-15 01:04:20
How does CELT scale with higher bitrate 80-128 kbps?
HE-AAC has good quality/size trade at 48-64 kbps but already no advantage over LC-AAC at 80 kbps.  While Vorbis vice versa.


CELT is actually designed to scale (i.e. keep improving) all the way up to ~510 kb/s in stereo. On the low side, it should go a bit lower than Vorbis, but not quite as low as HE-AAC.
Title: CELT 0.9.1 is out!
Post by: IgorC on 2011-03-15 15:02:55
~67 kbps test:
CELT 0.11.2 (complexity 10, bitrate 67.5 kbps, stereo, other settings by default)
Apple HE-AAC (constrained VBR 64 kbps, high quality: --high) (real bitrate ~67 kbps)
Vorbis Aotuv 6.02b q0.1

Setup: headphones Sennheiser HD 650, audio interface EMU Tracker Pre USB.

All files for CELT were resampled to 48 kHz by foobar resampler (PPHS, Ultra Mode enabled) as CELT is optimized for 48 kHz right now.

Bitrate verification on 10 albums:
CELT - 66.3 kbps
HE-AAC – 66.5 kbps
Vorbis – 66.5 kbps

Average score for 30 samples:
CELT – 3.36
HE-AAC – 2.91
Vorbis – 2.60

Excel table with results
mediafire.com/?qv2xa6sa8a9qa8v

Samples and logs.
mediafire.com/?lq21f6bz57v3d1d

The next test is at 96 kbps and then 128.
Title: CELT 0.9.1 is out!
Post by: NullC on 2011-03-16 12:27:28
~67 kbps test:
CELT 0.11.2 (complexity 10, bitrate 67.5 kbps, stereo, other settings by default)
Apple HE-AAC (constrained VBR 64 kbps, high quality: --high) (real bitrate ~67 kbps)
Vorbis Aotuv 6.02b q0.1


Hey— interesting findings!

The results for CELT vs the others are statistically significant according to bootstrap.py (not the the averages weren't clear enough)

I'm looking forward to seeing your other tests.

$ ./bootstrap.py -s 1000000 -p 40000 --blocked --compare-all res.txt
bootstrap.py v1.0 2011-02-03
Copyright © 2011 Gian-Carlo Pascutto <gcp@sjeng.org>
License Affero GPL version 3 or later <http://www.gnu.org/licenses/agpl.html>

Reading from: res.txt
Read 3 treatments, 30 samples => 3 comparisons
Means:
    CELT    HE-AAC    Vorbis
  3.360    2.907    2.597

Unadjusted p-values:
          HE-AAC    Vorbis 
CELT      0.012*    0.000* 
HE-AAC    -        0.130   

HE-AAC is worse than CELT (p=0.012)
Vorbis is worse than CELT (p=0.000)

p-values adjusted for multiple comparison:
          HE-AAC    Vorbis 
CELT      0.024*    0.000* 
HE-AAC    -        0.131   

HE-AAC is worse than CELT (p=0.024)
Vorbis is worse than CELT (p=0.000)
Title: CELT 0.9.1 is out!
Post by: LaserSokrates on 2011-03-16 13:27:25
Hey jmvalin, thank you and the team behind CELT for such an amazing codec. I only use it for speech (mumble) and the quality is amazing, as well as the latency.
Title: CELT 0.9.1 is out!
Post by: Ljubo44 on 2011-05-23 20:40:07
In any case,  since people asked... I create a win32 build of the 0.11.0 encoder and decoder tools:  https://people.xiph.org/~greg/celt/celt011-win32.zip (https://people.xiph.org/~greg/celt/celt011-win32.zip)


Link not working. Can someone upload celt encoder .. anyplace. Please.
Title: CELT 0.9.1 is out!
Post by: Anakunda on 2011-06-02 14:35:18
Hello there, tried to compile celtenc with library and no conversion is performed, anyone can say why??

Here's the binaries that don't work for me:
Code: [Select]
http://www.mediafire.com/?lioj5w9hi78vd26


Called with

celtenc test.wav test.oga

and nothing....
Title: CELT 0.9.1 is out!
Post by: 2304p on 2011-06-03 07:16:02
Hello there, tried to compile celtenc with library and no conversion is performed, anyone can say why??

Here's the binaries that don't work for me:
Code: [Select]
http://www.mediafire.com/?lioj5w9hi78vd26


Called with

celtenc test.wav test.oga

and nothing....


try this:
Code: [Select]
http://audiocoding.ru/celt.html

the current version is celt 0.11.2
Title: CELT 0.9.1 is out!
Post by: Anakunda on 2011-06-03 07:26:57
Thanks much, that's work. I'd be interested how's CELT performing as for quality in contest with Vorbis@Q6, Lame@V2 and NeroAAC@Q0.55.
Would anyone consider co-ordinate a listening test at these bitrates

the current version is celt 0.11.2


Where did you find that version? Official site still reports 0.11.1: http://www.celt-codec.org/downloads/ (http://www.celt-codec.org/downloads/)
Title: CELT 0.9.1 is out!
Post by: klonuo on 2011-06-03 08:01:37
You can get 0.11.2 also from here: http://listening-tests.hydrogenaudio.org/igorc/index.htm (http://listening-tests.hydrogenaudio.org/igorc/index.htm) and see test results at 64 Kb/s

Do you have any idea what it takes to make listening-test?
Title: CELT 0.9.1 is out!
Post by: lvqcl on 2011-06-03 10:43:54
version 0.11.4  available at http://git.xiph.org/?p=celt.git (http://git.xiph.org/?p=celt.git)
Title: CELT 0.9.1 is out!
Post by: klonuo on 2011-06-03 11:35:37
version 0.11.4  available at http://git.xiph.org/?p=celt.git (http://git.xiph.org/?p=celt.git)

So, where is 'configure'? - Process it with autoconf
OK, but it throws errors. - So you are stucked with Windows?
No, I'm just sick of packages that can't compile on MSYS or Cygwin on first try. *sigh*

...dream on for MSVC solutions...
Title: CELT 0.9.1 is out!
Post by: Anakunda on 2011-06-03 11:45:06
celt.c violates the C standard several times in the
  ALLOC_STACK;
  SAVE_STACK;
constructions (variable definition after statement), my compiler complains about that

could you please fix it

version 0.11.4  available at http://git.xiph.org/?p=celt.git (http://git.xiph.org/?p=celt.git)


please for link to tar.gz archive, I don't have git installed
Title: CELT 0.9.1 is out!
Post by: lvqcl on 2011-06-03 11:57:04
celt.c violates the C standard several times in the
  ALLOC_STACK;
  SAVE_STACK;
constructions (variable definition after statement), my compiler complains about that

Really? At least msvs2010 compiles it without problems.

please for link to tar.gz archive, I don't have git installed

It's there. Click on the first "snapshot" link.
Title: CELT 0.9.1 is out!
Post by: Anakunda on 2011-06-03 12:09:16
celt.c violates the C standard several times in the
  ALLOC_STACK;
  SAVE_STACK;
constructions (variable definition after statement), my compiler complains about that

Really? At least msvs2010 compiles it without problems.


I think VS2010 uses less strict lexical rules, but perhaps it would be better to stick with the standard strictly so that the code is truely portable. I'm using ICL.

please for link to tar.gz archive, I don't have git installed

It's there. Click on the first "snapshot" link.


Thanks
Title: CELT 0.9.1 is out!
Post by: 2304p on 2011-06-04 15:09:25
version 0.11.4  available at http://git.xiph.org/?p=celt.git (http://git.xiph.org/?p=celt.git)


Thanks!
I have downloaded this snapshot, how to compile celt-0.11.4.tar.gz to exe and dlls (32bit)?
Title: CELT 0.9.1 is out!
Post by: lvqcl on 2011-06-04 16:28:32
Either I cannot compile CELT 0.11.4 correctly, or it is incompatible with current foo_input_celt (http://www.foobar2000.org/components/view/foo_input_celt).
Title: CELT 0.9.1 is out!
Post by: klonuo on 2011-06-04 19:37:12
I have downloaded this snapshot, how to compile celt-0.11.4.tar.gz to exe and dlls (32bit)?

Assuming you are on Windows with MSVC < 10:

1. open MSVS and make empty project for libcelt from files from libcelt folder and build it
2. download libogg and build it
3. make separate projects for celtenc and celtdec* with linker dependant on already build libcelt and libogg libraries
* from files in tools folder (read Makefile.am as a help)

If you setup everything in those steps correctly, you should have celtenc and celtdec executables
Title: CELT 0.9.1 is out!
Post by: 2304p on 2011-06-04 22:42:10
I have downloaded this snapshot, how to compile celt-0.11.4.tar.gz to exe and dlls (32bit)?

Assuming you are on Windows with MSVC < 10:

1. open MSVS and make empty project for libcelt from files from libcelt folder and build it
2. download libogg and build it
3. make separate projects for celtenc and celtdec* with linker dependant on already build libcelt and libogg libraries
* from files in tools folder (read Makefile.am as a help)

If you setup everything in those steps correctly, you should have celtenc and celtdec executables


i use minGW32
Title: CELT 0.9.1 is out!
Post by: klonuo on 2011-06-04 23:03:30
run automation bash script provided and then as readme says just compile with ./configure; make

or forget about it
Title: CELT 0.9.1 is out!
Post by: 2304p on 2011-06-05 12:46:48
can you compile celt-0.11.4.tar.gz and upload as celt-0.11.4-win32.zip?

google doesn't help me further.
Title: CELT 0.9.1 is out!
Post by: Anakunda on 2011-06-05 13:38:40
I can compile but for me it doesnot encode anything and exits.
Title: CELT 0.9.1 is out!
Post by: lvqcl on 2011-06-05 16:38:33
Celt 2011-04-21: [attachment=6643:celt_2011_04_22.7z]

(re-uploaded: compiled with CUSTOM_MODES=1. Source and *.exe included)
Title: CELT 0.9.1 is out!
Post by: 2304p on 2011-06-05 17:59:56
Celt 2011-04-21: [attachment=6540:celt_201...21_win32.7z]

thank you
Title: CELT 0.9.1 is out!
Post by: darkbyte on 2011-11-13 09:00:44
Hi!

First, thanks for this truly amazing codec. I'm excited to see where this codec advances in the future

I'm curious if it's possible to implement a similar technology like bitrate peeling in Vorbis which was actually never used there. It would be so nice to use CELT for eg. web radio streaming where the client could decide according to it's current connection speed the bitrate it requests and switch between them gaplessly. Say, the main encoder encodes the audio @192kbps, but it can be peeled down to 96kbps or 48kbps without transcoding on the audio server by sending less data. When you listen to web radio on eg. your mobile phone while moving in your car you roam between cells but not all of them supports high speed connection for example, on EDGE the web radio player on the phone can revert to 48kbps so it can keep up with continous streaming. What do you think? As i read CELT scales very well so maybe it's not impossible to arrange encoded data in a peelable way.
Title: CELT 0.9.1 is out!
Post by: NullC on 2011-11-14 08:23:19
I'm curious if it's possible to implement a similar technology like bitrate peeling in Vorbis which was actually never used there. It would be so nice to use CELT for eg. web radio streaming where the client could decide according to it's current connection speed the bitrate it requests and switch between them gaplessly. Say, the main encoder encodes the audio @192kbps, but it can be peeled down to 96kbps or 48kbps without transcoding on the audio server by sending less data. When you listen to web radio on eg. your mobile phone while moving in your car you roam between cells but not all of them supports high speed connection for example, on EDGE the web radio player on the phone can revert to 48kbps so it can keep up with continous streaming. What do you think? As i read CELT scales very well so maybe it's not impossible to arrange encoded data in a peelable way.


For files encoded with Opus using the hybrid mode, they can be stripped to just the low frequency parts inexpensively.  Otherwise, no. Part of the efficiency of the format comes from making the coding so right that 'pealing' is not possible.

On the other hand, our encoder is fairly fast— the fairly unoptimized reference code (No ASM, No SIMD) is >12x faster than libvorbis' managed mode encoding.  You should also be able to switch clients between different bitrate sources on a packet by packet basis without breaking continuous streaming.

Title: CELT 0.9.1 is out!
Post by: darkbyte on 2011-11-14 16:57:38
For files encoded with Opus using the hybrid mode, they can be stripped to just the low frequency parts inexpensively.  Otherwise, no. Part of the efficiency of the format comes from making the coding so right that 'pealing' is not possible.

I see. And how about the other end? Making CELT scalable to lossless? That would very nice also. 96kbps for portable listening is already nice, but what about storing correction data? Like HD-AAC does.
Title: CELT 0.9.1 is out!
Post by: Gainless on 2011-12-12 21:37:42
Can someone re-compile the celt version 0.11.4 to an exe file?
I didn't really get through how to do it by myself...
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