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Any listening test Stereo vs Joint stereo in mp3?
Bogalvator
post Jan 22 2005, 04:49
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QUOTE (Gabriel @ Jan 21 2005, 04:55 AM)
Well, in your case intensity stereo is a good thing compared to l/r stereo, considering that UK DAB is something like 128kbps Layer II.
*


Yuck! I thought it sounded a bit fishy to be honest when I was listening in my mate's car the other day. Seems I'll save my money rather than investing in DAB car audio (which also doesn't work under bridges etc, just like AM rolleyes.gif)

Hey David where is this forum you were on?

I can't understand all the fretting about J/S and it's possible effect on stereo image etc - so what if it was lossy? The point is does it improve quality, and at higher bitrates, is it ABX-able etc? Remember that Lame cuts off frequencies above 18000 Hz at -V 2, what's the difference between that and a hypothetical undetectable loss of stereo image?

Doesn't Vorbis implement lossy stereo on q values less than 6? How well did it do in the last 128kbps test again (-q 4.35 used)?

Perhaps people aren't as sensitive to "stereo image" as they'd like to think!
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2Bdecided
post Jan 24 2005, 17:00
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QUOTE (Gabriel @ Jan 21 2005, 12:55 PM)
Well, in your case intensity stereo is a good thing compared to l/r stereo, considering that UK DAB is something like 128kbps Layer II.
*


Well, yes, but the argument was that joint stereo was OK because (pointers to articles about mp3 joint stereo) - I was trying to argue that, if you _have_ to use joint stereo with mp2, then it can't be transparent - basically because the bitrate is too low.


btw (you people in other countries can have a good laugh about this if you want) - UK DAB digital radio is set to change - if the regulator gets its way, the 128kbps limit will be removed, and replaced by a -2.0 diff grade limit. No idea how this will be measured or enforced, but the broadcasters have reportedly asked for this change so they can move stations down to 112kbps mp2 joint stereo.

Won't that sound nice? ohmy.gif crying.gif

Some people think that DAB stands for Dead And Buried.

Cheers,
David.
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Gabriel
post Jan 24 2005, 20:41
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QUOTE
but the broadcasters have reportedly asked for this change so they can move stations down to 112kbps mp2 joint stereo.

This will be a good example related to "things to not do"
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Ossie
post May 21 2005, 10:57
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Hi, I just want to check if the following staement has any validity for music encoded using LAME in Joint Stereo....

Some music contains sounds that are deliberately delayed or phase shifted. Such effect boxes are called "flanger", "phaser" and the like. If you encode such music in 'joint stereo', you will have bad cancelling effects where the high tones appear and disappear all the time, destroying the good original sound. One old example is the accompanying guitar in Paul Simon's "Mrs. Robinson".

Thanks
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Pio2001
post May 21 2005, 13:01
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It all depends if the psychoacoustic model can handle them. Some tests need to be done.
You'll have to start from low bitrates in order to try to catch the issue.
If the issue exists, you then need to see if it is still ABXable at high bitrate.
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Pio2001
post May 21 2005, 13:07
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Oh, that's not all, you'll have to force mid/side stereo vs left/right stereo for the comparison, then see what stereo mode joint stereo chooses.

I think that a square wave with some pulses would be a good test signal.
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mjkng2
post Aug 4 2006, 19:20
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hey
this is an old article against Joint Stereo: http://harmsy.freeuk.com/mostync/

I don't know, where's the truth. ?
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stephanV
post Aug 4 2006, 20:16
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It's not against JS... it just says that an algorithm that works good in theory can be implemented in a a bad way in. That's not something new or spectacular.


--------------------
"We cannot win against obsession. They care, we don't. They win."
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Pio2001
post Aug 4 2006, 22:52
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I've performed two joint stereo listening tests since then.
One with a very special sample : http://www.hydrogenaudio.org/forums/index....st&p=349785
One with a normal killer sample : http://www.hydrogenaudio.org/forums/index....st&p=404949
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haregoo
post Aug 5 2006, 03:57
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This sample is ABXable(16/16) even with -V 0 because of joint stereo.(I confirmed with 3.97b2 and 3.98a6)
JS causes a bit stereo image corruption.

Maybe I made some mistake in a bunch of procedure(encoding, decoding, ABX...etc), so correct me if I'm wrong.

This post has been edited by haregoo: Aug 12 2006, 05:53
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Gabriel
post Aug 5 2006, 08:48
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QUOTE (haregoo @ Aug 5 2006, 04:57) *
This sample is ABXable(16/16) even with -V 0 because of joint stereo.(I confirmed with 3.97b2 and 3.98a6)
JS causes a bit stereo image corruption.

Then please report it in this thread:
http://www.hydrogenaudio.org/forums/index....showtopic=39314

Regarding joint stereo or not, have you tryed to ABX with and without joint stereo?
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Garf
post Aug 5 2006, 09:44
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QUOTE (mjkng2 @ Aug 4 2006, 20:20) *
hey
this is an old article against Joint Stereo: http://harmsy.freeuk.com/mostync/

I don't know, where's the truth. ?


I think you failed to understand something, because the article is in favor.
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haregoo
post Aug 5 2006, 14:14
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QUOTE (Gabriel @ Aug 5 2006, 16:48) *
Regarding joint stereo or not, have you tryed to ABX with and without joint stereo?

I've done multiple trials with and without -ms.
e.g. 3.97b2 -V 5 --vbr-new vs -V 5 --vbr-new -ms
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