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Topic: Quite OK Audio (QOA)... anyone ? (Read 13687 times) previous topic - next topic
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Re: Quite OK Audio (QOA)... anyone ?

Reply #50 –
@Porcus (I) At lower sampling rates, noise shaping can't push the noise into the inaudible frequencies because they are above the Nyquist limit. (I) I don't know the ideal values.

Re: Quite OK Audio (QOA)... anyone ?

Reply #51 –
AFAIC noise shaping is not implemented in QOA reference encoder.
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Re: Quite OK Audio (QOA)... anyone ?

Reply #52 –
Quote from: Klymins on
@Porcus (I) At lower sampling rates, noise shaping can't push the noise into the inaudible frequencies because they are above the Nyquist limit. (I) I don't know the ideal values.
AFAIC 3bit should be enough for low sample rates.
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Re: Quite OK Audio (QOA)... anyone ?

Reply #53 –
@mycroft First answer: This does not change anything, noise shaping still can't push the noise into the inaudible frequencies at these lower sampling rates because they are above the Nyquist limit.

Second answer: 3-bit is pretty easy to ABX, here's an example: https://drive.google.com/drive/folders/1d40gGr2tG4xwBiNR1TR-PBZhorsT56G2?usp=drive_link . I did another ABX ang got 15/16 again, here's the link: https://drive.google.com/drive/folders/1MFflZFOMUDgiFV0bNuLcPGU7BAYOY2o2?usp=drive_link . Looks like QOA is pretty noisy in low sampling rates. Also, according to my ears, it has lower quality than 5-bit Flash ADPCM in most cases.

Re: Quite OK Audio (QOA)... anyone ?

Reply #54 –
Thus my valid claim that QOA encoder can be improved: adding noise shaping, improving current encoding.
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Re: Quite OK Audio (QOA)... anyone ?

Reply #56 –
@Porcus At a low sampling rate like 5512.5Hz, you can't even access to 4kHz. Having another option for higher quality does not hurt someone.

Re: Quite OK Audio (QOA)... anyone ?

Reply #57 –
I agree with all three of you. Hence my previous two posts in this thread, where the latter includes a solution for (relatively) simple but robust noise shaping.

Psychoacoustically, a high coding SNR is needed especially in lower frequencies. In case of a CDish sampling rate, you could achieve that by noise shaping during quantization, but with lower sampling rates, you can't. So in the latter case, indeed increasing the bit-depth is the only option I see.

But I don't think the QOA developer intends to change the QOA spec in that regard, am I right?

Chris
If I don't reply to your reply, it means I agree with you.

Re: Quite OK Audio (QOA)... anyone ?

Reply #58 –
A mighty 3 octaves down from CDDA is quite a departure, and you wouldn't expect quality reproduction of music there in any case. But it does something to your need for bitrate.

* How dows it compare to https://github.com/dbry/adpcm-xq ?
* How low can you go with LossyWAV --> flac -8pb512 ?  The 1.4.3 beta has a few new presets at the low end:
https://hydrogenaud.io/index.php/topic,109239.msg1045012.html#msg1045012

Re: Quite OK Audio (QOA)... anyone ?

Reply #59 –
@Porcus Sampling rate is independent from quality and it is not an unusable sampling rate, some Flash games were used it in their musics.

As ADPCM-XQ does not use predictions, it can't reach QOA's quality in most cases. Also, LossyWAV uses frequency domain if I understood correctly and this makes it very complex from beginning.

I don't understand why you don't want having a 4-bit variation of QOA. I think it will be very useful as Flash ADPCM also has 2, 3, and 5 bit variations and they are very useful.

Re: Quite OK Audio (QOA)... anyone ?

Reply #60 –
Quote from: Klymins on
Sampling rate is independent from quality

*sighs*


Quote from: Klymins on
I don't understand why you don't want having a 4-bit variation of QOA.

I didn't say that.
You need to realize that <freeware developer> isn't obliged to to create <software to your demand> for you for free.
If you need an altered version in <software project>, feel free to take note that it is MIT licensed.

Re: Quite OK Audio (QOA)... anyone ?

Reply #61 –
@Porcus  Yes, <freeware developer> isn't obliged to to create <software to my demand> for me for free, but you should not sigh because sampling rate (and channels as well) are independent from quality. As the sampling rate increases, the average quality that you will get with the same codec at the same bitrate will decrase, and vice versa. For example, 32kbps MP3 is pretty transparent to me, but only at a relatively low sampling rate (for example 11025Hz) with mono. But, the MP3 stream must be at least ~96kbps to be transparent to me at 22050Hz stereo. However, this value isn't ~192kbps for 44100Hz stereo because my hearing cutoff starts to affect the sound at this point. This is not quality. Speed (sampling rate or cutoff), channels, and quality are completely independent variables.

Re: Quite OK Audio (QOA)... anyone ?

Reply #62 –
From "sampling rate is independent from quality" to at the same bitrate in one goalpost displacement.

Also, 11025 kHz at 64 bits/sample is the same bitrate as CDDA.

Re: Quite OK Audio (QOA)... anyone ?

Reply #63 –
You're right.

Re: Quite OK Audio (QOA)... anyone ?

Reply #64 –
By the way, I was sleepy when writing one of the messages above. I mean "and got 16/16" by "ang got 15/16", and the log in the drive folder verifies this.

Re: Quite OK Audio (QOA)... anyone ?

Reply #65 –
@Porcus 11025 kHz?

Re: Quite OK Audio (QOA)... anyone ?

Reply #66 –
I have wrote QOA encoder, it distorts less higher frequencies and helps a lot for @Klymins 16000Hz sample (still not perfect, but at least it does not give those harsh sounds that make it trivially easy to ABX especially at lower sample rates) at cost of little smaller dB of SDR/PSNR score.
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Re: Quite OK Audio (QOA)... anyone ?

Reply #67 –
@mycroft How can I get it?

Re: Quite OK Audio (QOA)... anyone ?

Reply #69 –
Quote from: Klymins on
@mycroft How can I get it?
Librempeg code. (I got couple of clicks when converting >2 hour OST 48kHz music to .QOA dunno is it bug because of my changes or because of original algorithm) but for 16kHz speech sample rate in your short sample its 99% transparent.
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Re: Quite OK Audio (QOA)... anyone ?

Reply #70 –
In case anyone is interested, I made an alternative QOA decoder component for foobar2000 using a self-written decoder based on the specs. The component can be downloaded here: https://foobar.hyv.fi/?view=foo_input_qoa.
This component should implement all QOA features. Channel support has no artificial limits, streaming format is supported, the correct channel maps are used as documented in the specs. Seeking is sample-accurate. Tagging is supported and I added custom support for overriding default channel order with a tag.

Re: Quite OK Audio (QOA)... anyone ?

Reply #72 –
Quote from: mycroft on
Librempeg code. (I got couple of clicks when converting >2 hour OST 48kHz music to .QOA dunno is it bug because of my changes or because of original algorithm)
I encoded a test audio album with librempeg and had very nasty beeps and squeks in the first track at around time mark 2:45. I verified the same track with the reference qoaconv encoder and it didn't produce any glitching.

Re: Quite OK Audio (QOA)... anyone ?

Reply #73 –
@mycroft, the QOA encoder in librempeg glitches because you disabled the reference encoder's weights overflow penalty check.
Here's win64 compile of qoaconv modified with mycroft's encoding changes but with weight checks in place. Doesn't glitch in my test file and produces audibly identical results from Klymins' samples with librempeg.

Edit: Added qoaconv_mod.zip with a version of qoaconv that doesn't reject WAVE_FORMAT_EXTENSIBLE WAV files and includes three different encoding modes.
Usage: qoaconv [mode] input.wav output.qoa
Mode '0' is the default, reference encoder. '1' uses the Librempeg-inspired version and '2' is based on reference encoder's noiseshaping branch.
 

Re: Quite OK Audio (QOA)... anyone ?

Reply #74 –
I also have small patch to fix initial samples prediction if they are not 0. But whole codec design and exp implementation is flawed/limited. My idea is to always recompute weights at start of frame but that causes artifacts ...
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