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Topic: Another Joint Stereo Discussion (Read 38950 times) previous topic - next topic
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Another Joint Stereo Discussion

[span style='font-size:8pt;line-height:100%']Split from here.[/span]

Quote
Has anyone ever had a hard job trying to dispell certain mp3 myths? Like:

1) Joint Stereo messes up the sound.
2) Joint Stereo ruins high frequencies.
3) You can always tell the difference.

etc etc.

I feel like I'm bashing my head against a brick wall trying to talk to these people... 
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Although I agree with you that most people are not going to notice the difference between a stereo/js encoded mp3 implying that the difference is mythical, or even inaudible is plain wrong.

It seems to me that the difference is more profound when using VBR.

If you encode a file twice with the same VBR settings except for s/js setting, and then turn them back to wavs (so there is no size difference) and email me the same 10 seconds of each I am willing to bet you I can tell them apart.

And I am wearing flame proof armor!

cAPS

Another Joint Stereo Discussion

Reply #1 –
cAPSLOCK, unless you can prove it yourself, by providing an uncompressed sample that sounds worse to you when encoded with mid-side joint stereo rather than "pure" stereo, and prove that you can tell the difference through double-blind testing, no one here is going to take you seriously.

Another Joint Stereo Discussion

Reply #2 –
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Is there any reason we would ever really need simple stereo since Lame JS doesn't destroy stereo?

If no one can think of a good reason, maybe it should be taken out of Lame, or at least taken out of the --longhelp and removed from the docs. What do you think?
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I can think of a reason.

The is an audible difference between the two.    I would like the choice of how I encode.

For what it's wirth I normally encode in joint stereo.

Here is one way to prove the difference.

The following two files are the S channel of the same exact file (recorded in my studio) one encoded in joint stereo and one encoded in stereo.

[a href="http://noisevault.com/temp/hyd-js.wav]http://noisevault.com/temp/hyd-js.wav[/url]
http://noisevault.com/temp/hyd-s.wav

If you dont have decent speakers... listen with headphones.  You will hear the difference.

Here is what I did:

Took a song and encoded it VBR 112-320 both in stereo and joint stereo.  Then I did a Mid/Side encoding on it and isolated the Side channel.  That's what you have downloaded. 

If you don't know about mid-side encoding it's pretty simple.  It is just another way to represent a stereo signal over two channels.  Instead of left and right, you have the audio that is in the middle, and the audio that is on the sides.  Google up M/S encoding if you want to know more.

For the sake of reference here is the original wav that was encoded.  Well more or less... I cut out the pieces after I encoded the whole 4 minute files.

http://noisevault.com/temp/hyd-orig.wav

regards,
cAPS

Another Joint Stereo Discussion

Reply #3 –
Quote
cAPSLOCK, unless you can prove it yourself, by providing an uncompressed sample that sounds worse to you when encoded with mid-side joint stereo rather than "pure" stereo, and prove that you can tell the difference through double-blind testing, no one here is going to take you seriously.
[a href="index.php?act=findpost&pid=278061"][{POST_SNAPBACK}][/a]


Can you tell a difference between the S channel files I posted? (about three posts up)

cAPS

Another Joint Stereo Discussion

Reply #5 –
Do you mean you don't think I could tell a j/s encoded mp3 from an uncompressed wav file?  If so, then you are completely insane. 

Or am I misunderstanding you?

cAPS

Another Joint Stereo Discussion

Reply #6 –
I was thinking you meant joint stereo was inferior. Oh well.

But nevertheless, when you registered here, you agreed to the Terms of Service.

Quote
8. All members that put forth a statement concerning subjective sound quality, must -- to the best of their ability -- provide objective support for their claims. Acceptable means of support are double blind listening tests (ABX or ABC/HR) demonstrating that the member can discern a difference perceptually, together with a test sample to allow others to reproduce their findings. Graphs, non-blind listening tests, waveform difference comparisons, and so on, are not acceptable means of providing support.


You have just made some statements regarding sound quality. If you can back up your claims, then please do so in a manner which is acceptable by this community, without resorting to comparisons between "artificial" samples.

I bet there are some cases where you wouldn't be able to tell a LAME 3.9x encoded 320kbps CBR mid-side j/s MP3 from an uncompressed original.

Another Joint Stereo Discussion

Reply #7 –
Oh, I get it...

You are telling me that j/s vs stereo encoding is analogous to M/S encoding.

This would be true but for the mp3 encoding happening on top of it.

The bits saved by j/s encoding are GOING somewhere.  Where do you think? 

I am an audio professional.  It's what I do for a living.  I listen to sound up close all day long over a  fairly nice signal chain.  I modified the A/D D/A converters I use myself.  I know there is a difference between stereo and joint stereo encoding.  I even provided proof that anyone should be able to hear the difference in a post a above this one.

I understand I have walked into a holy topic throwing bombs... I will shut up now.

But it was this thread that made me join hydrogen audio finally after a long time of moderate trolling...  I do not promise to not throw other bombs elsewhere.

love,
cAPS

Another Joint Stereo Discussion

Reply #8 –
I was implying that mid-side, not intensity-stereo,  is the proper way to do high quality joint-stereo.

It doesn't matter if you're an audio professional. If you can't back up your claims here, no one will take you seriously, as I have pointed out before.

Another Joint Stereo Discussion

Reply #9 –
Woof... You are right... "Number 8" is a pretty serious part of the agreement.

I retract all my statements as I do not have enough time to enter a double blind test over the internet (actually I am audition mic preamps via some blind (not double blind haha  I won't cheat my wallet) testing this week before I purchase a new one).

But wouldn't it be unfair to say things like
Quote
I bet there are some cases where you wouldn't be able to tell a LAME 3.9x encoded 320kbps CBR mid-side j/s MP3 from an uncompressed original.
" without providing the same level of proof?

Or does the rule only apply to me?

 

cAPS

Another Joint Stereo Discussion

Reply #10 –
Quote
Do you mean you don't think I could tell a j/s encoded mp3 from an uncompressed wav file?  If so, then you are completely insane. 

Or am I misunderstanding you?

cAPS
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Try it (with a good encoder and settings, don't cheat  ) and then tell us.

I think you will be surprised.

And if you can, PLEASE post the sample (uncompressed) and results
I'm the one in the picture, sitting on a giant cabbage in Mexico, circa 1978.
Reseñas de Rock en Español: www.estadogeneral.com

Another Joint Stereo Discussion

Reply #11 –
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The bits saved by j/s encoding are GOING somewhere.

Uh.... where exactly are they going?

Another Joint Stereo Discussion

Reply #12 –
Quote
But wouldn't it be unfair to say things like
Quote
I bet there are some cases where you wouldn't be able to tell a LAME 3.9x encoded 320kbps CBR mid-side j/s MP3 from an uncompressed original.
" without providing the same level of proof?

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This has been already proven.

I'm not saying that you couldn't do it, but it is very hard.

MP3s produced by LAME 3.9x at that bitrate are pretty much transparent.

But, then again, try.
I'm the one in the picture, sitting on a giant cabbage in Mexico, circa 1978.
Reseñas de Rock en Español: www.estadogeneral.com

Another Joint Stereo Discussion

Reply #14 –
Quote
Try it (with a good encoder and settings, don't cheat   ) and then tell us.

I think you will be surprised.

And if you can, PLEASE post the sample (uncompressed) and results
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OK... I admit it... I am ensnared by your challenge.

What exactly do you want me to do that will prove I can hear a difference?

If it is within reasonable limits I will do anything to either prove I am right... or you are.

cAPS

Another Joint Stereo Discussion

Reply #15 –
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It does not apply to me, because it was merely a counterclaim. The ball is in your court, but you seem to have retracted all your statements.
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Oh... I was just being dramatic.  I still know I can hear a difference.  And if you want I will attempt a test, but what do I need to do to convince you?

But doesnt the general notion that "audible JS encoding differences are a myth" put forth by this very thread deserve the scrutiny of rule #8?  Or is this "the doctrine of the church" and doesnt have to be supported?  Is there proof already?

cAPS

Another Joint Stereo Discussion

Reply #16 –
The myth in question is "Joint stereo, even mid-side jointstereo, is worse than pure stereo."

It has been proven wrong, under strict conditions, I am sure.

Another Joint Stereo Discussion

Reply #17 –
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But doesnt the general notion that "audible JS encoding differences are a myth" put forth by this very thread deserve the scrutiny of rule #8?  Or is this "the doctrine of the church" and doesnt have to be supported?  Is there proof already?

Read the FAQ

Another Joint Stereo Discussion

Reply #18 –
Quote
Quote
The bits saved by j/s encoding are GOING somewhere.

Uh.... where exactly are they going?
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They are going *POOF* and disappearing.

cAPS

Another Joint Stereo Discussion

Reply #19 –
Quote
What exactly do you want me to do that will prove I can hear a difference?

If it is within reasonable limits I will do anything to either prove I am right... or you are.

cAPS
[a href="index.php?act=findpost&pid=278083"][{POST_SNAPBACK}][/a]


Find a music sample in which you can hear a difference caused by incorrect stereo information produced by joint stereo encoding.

Perform a blind test vs uncompressed wav file (using whatever bitrate is transparent for you in MP3 encoding, but I suggest --alt-preset standard or equivalent in later LAMEs) or versus MP3 encoded using full stereo.

Provide results.

That sounds reasonable, doesn't it?

And it is not a challenge. This community and the codec developers who post here are very open to criticism which is constructive, scientific and will encourage the improvement of compressed audio. We really love when somebody finds anything that will work towards the perfecting of codecs.

It would not be the first time either result would happen.
I'm the one in the picture, sitting on a giant cabbage in Mexico, circa 1978.
Reseñas de Rock en Español: www.estadogeneral.com

Another Joint Stereo Discussion

Reply #20 –
Quote
Quote
Quote
The bits saved by j/s encoding are GOING somewhere.

Uh.... where exactly are they going?
[a href="index.php?act=findpost&pid=278080"][{POST_SNAPBACK}][/a]


They are going *POOF* and disappearing.

cAPS
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Thus making a smaller file--one of the main reasons to use mp3, no?

Another Joint Stereo Discussion

Reply #21 –
cAPS, if you want your claims to be taken seriously do the following:

1. Encode a sample of your choice using LAME 3.90.3 with these two commandlines:
--alt-preset standard
--alt-preset standard -m s

2. ABX both samples from the original and each other (That makes 3 ABX tests overall).  I assume you - as a professional - are familiar with ABX methodology, if not read this. I recommend using foobar2000's foo_abx component.

3. Post your results and a losslessly compressed version of the sample you used for others to verify your findings.

4. Decide if you stick to your claim that "Joint stereo, even mid-side jointstereo, is worse than pure stereo."
"To understand me, you'll have to swallow a world." Or maybe your words.

Another Joint Stereo Discussion

Reply #22 –
Quote
Quote
Quote
Quote
The bits saved by j/s encoding are GOING somewhere.

Uh.... where exactly are they going?
[a href="index.php?act=findpost&pid=278080"][{POST_SNAPBACK}][/a]


They are going *POOF* and disappearing.

cAPS
[a href="index.php?act=findpost&pid=278094"][{POST_SNAPBACK}][/a]

Thus making a smaller file--one of the main reasons to use mp3, no?
[a href="index.php?act=findpost&pid=278097"][{POST_SNAPBACK}][/a]


Certainly!  This is why I use JS encoding for the most part!  But by that logic, why encode at 320 ro even 192?  Why not just drop the file down to the lowest bitrate you possibly can for 44.1 audio?  Every bit you lose changes something from the original file when using lossy encoding.

cAPS

PS Man I hate those forum bombthrowers who promise to shut up and continue to hi-jack a thread...  Seems I hate myself!  See I am open to being wrong.

Another Joint Stereo Discussion

Reply #23 –
Quote
cAPS, if you want your claims to be taken seriously do the following:

1. Encode a sample of your choice using LAME 3.90.3 with these two commandlines:
--alt-preset standard
--alt-preset standard -m s

2. ABX both samples from the original and each other (That makes 3 ABX tests overall).  I assume you - as a professional - are familiar with ABX methodology, if not read this. I recommend using foobar2000's foo_abx component.

3. Post your results and a losslessly compressed version of the sample you used for others to verify your findings.

4. Decide if you stick to your claim that "Joint stereo, even mid-side jointstereo, is worse than pure stereo."
[a href="index.php?act=findpost&pid=278098"][{POST_SNAPBACK}][/a]


Alright.  I will do this and post the results.

cAPS

Another Joint Stereo Discussion

Reply #24 –
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But by that logic, why encode at 320 ro even 192?  Why not just drop the file down to the lowest bitrate you possibly can for 44.1 audio?  Every bit you lose changes something from the original file when using lossy encoding.


However....

Quote
The M/S stereo transform itself is lossless.
However, in the context of a lossy encoder, anything leading to some variations in the bits might affect the final loss.
It means that in the context of mp3 encoding, M/S stereo is as lossy as the Huffman coding.