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Topic: Is MP3 joint stereo the preferred mode? (Read 10717 times) previous topic - next topic
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Is MP3 joint stereo the preferred mode?

I've noticed that a number of the front end GUI's such as LAMEdropXP, use
JS exclusively, regardless of the bitrate.

I thought stereo was the preferred mode for the higher bitrates.  Is this not true?
If not, was it ever true?

Thanks for any information -
Dave

Is MP3 joint stereo the preferred mode?

Reply #1 –
JS is always preferred.

Is MP3 joint stereo the preferred mode?

Reply #2 –
Interesting.  Thanks for responding. 

Perhaps it's a common misconception?  I'm certainly not alone in the belief
that "stereo" provided a more natural sound at the higher bitrates, and that
JS was a compromise to allow lower bitrate encodes to sound better.

If that's wrong, then I'll stand corrected.

Is MP3 joint stereo the preferred mode?

Reply #3 –
Quote from: davexnet on
belief
There is no need for a faith-based approach on this topic.

http://www.hydrogenaudio.org/forums/index....showtopic=16295

Is MP3 joint stereo the preferred mode?

Reply #4 –
I haven't done an ABX test, but I just did a few encodes of various uncompressed music styles, and I'm very impressed
with LAME 3.99.  I'm pretty sure I would not be able to tell the difference on the sound equipment I have at home.

But if you go back 5 - 10 years, some of the earlier encoders - I don't think the JS algorithms were as sophisticated
as they are now.  I  seem to remember encoding to JS years ago, decided it sounded harsh and unnatural
compared to the stereo, and abandoned it.  I've been prejudiced against it ever since.


Is MP3 joint stereo the preferred mode?

Reply #5 –
The problem with your assertion is that LAME has undergone significant improvements during that time. Pages which detail the "failings" of joint stereo, like this one:

http://lame.sourceforge.net/ms_stereo.php

are more than a decade old. If you look at the second to last paragraph, it references LAME 3.21, which was released on July 26, 1999. If you look at the LAME ChangeLog, you can see the slew of updates which have happened since then.

Based on your original question, it is also worth being clear by saying that joint stereo is not itself a stereo mode; the modes are left/right stereo and middle/side stereo. Joint stereo allows LAME to switch between the two freely within the same file on a frame-by-frame basis depending on which mode it believes will yield the best quality:filesize ratio.

When you say that you've heard LR stereo is better for higher bitrates, that is somewhat true, but like most things, it isn't black and white. Try using LAME's various VBR presets, like V2, V1, and V0 on the same input file, and you will see the number of LR frames increases while the number of MS frames decreases with higher quality settings. As you raise the quality setting, LAME uses more bits and can afford to use LR stereo on more frames. The point is that LAME is smart enough to decide whether LR or MS is optimal for a specific frame at a specified quality, and letting LAME decide what to do is the purpose of JS mode. You should therefore never force it to always use LR or MS. If you do, you're just needlessly degrading the quality and/or raising the filesize from what you would otherwise get if you used the normal preset.

If the wisdom of the LAME developers isn't enough to satisfy you, your only course of action is to follow greynol's link and conduct blind ABX tests. If you want to prove the worth of JS to yourself, try to ABX an original WAVE against two MP3s that only differ in whether JS mode or LR mode was used. If you can't ABX either of them against the original, you might as well use JS, since it's saving space without an audible quality degredation. If you can ABX both of them against the original, you aren't using a high enough quality setting, so your test isn't letting you compare the merits of left/right vs joint stereo. You could only support your position of saying LR mode is superior by being able to ABX the JS file but not the LR file against the original.

Hopefully I haven't made any mistakes in all of this, but I'm sure one of the veterans will correct me if I did.

Is MP3 joint stereo the preferred mode?

Reply #6 –
Quote from: davexnet on
Perhaps it's a common misconception?
Oh yes! As a search of the forum would reveal.

In addition to a great post by Aleron Ives, I will add that the implementation of joint stereo in LAME is mathematically lossless. That is, the transformation itself does not degrade quality; in combination with the ability to choose M/S or L/R on a per-frame basis, as AI has said, the potential for accurate reproduction of the input signal is greatly increased.

If you were to use forced mid/side stereo (i.e. full joint stereo), then sure, things might be different. But the same holds true for forced simple stereo. Again, considerations such as these are precisely why LAME defaults to, and people here recommend, a flexible mode that can mix the two types of frame.

Is MP3 joint stereo the preferred mode?

Reply #7 –
Joint stereo's bad reputation was well deserved, but not because it was an inferior technology or incapable of producing good results, but rather just because it was poorly implemented in the earliest MP3 encoders.

At least one formerly popular encoder (from 10+ years ago) was the unofficial "Radium" distribution of the Fraunhofer "professional" codec. The original codec was only licensed for use from within certain commercial audio apps. The Radium version was this codec, but with an installer, and modified with some optimizations and a custom control panel where you had to choose which stereo mode and high-quality mode went with which bitrate. I don't know if this was a feature of the FhG code or of Radium's modifications, but it only allowed the user to select certain combinations, and its joint stereo option didn't actually do any intelligent mode switching whatsoever, but rather just generated 100% mid/side frames (or intensity stereo frames at low bitrates). The FAQ distributed with this pirate codec warned of using its joint stereo could result in 'flanging' or 'swishing' effects, which I recall was a very real phenomenon, presumably a result of the side channel being starved of bits. The FAQ recommended sticking to 'stereo' mode (100% left/right frames) at higher bitrates or when the stereo field was particularly 'wide'.

I don't think any modern encoder implements joint stereo so poorly; automatic switching of modes as needed for quality is the standard nowadays.

Is MP3 joint stereo the preferred mode?

Reply #8 –
About 14 years ago I used to hate it when people use 'Stereo' instead of 'Joint-Stereo'  to encode to MP3 at 128Kbit/s. Don't know how to describe the sound, but it didn't sound natural. That is my reason for sticking to 'Joint-Stereo' at any bitrate.

Is MP3 joint stereo the preferred mode?

Reply #9 –
Thanks very much everybody for discussing this subject.
I listen to some of the 128kbps mp3's I made 10 years ago and they sound terrible.
Not sure what encoder I used, but even then, I probably could have done better by using VBR.

We've come a long way since those old "radium" days.  I've played around with -V 1.30 to -v 1.50
and it's quite impressive.

Regarding this statement by Aleron Ives, "Try using LAME's various VBR presets, like V2, V1, and V0 on the same input file, and you will see the number of LR frames increases while the number of MS frames decreases with higher quality settings."

What is it that shows you the ratio or LR frames to MS frames ?  Some front end GUI or other?

Is MP3 joint stereo the preferred mode?

Reply #10 –
It’s among the statistics output by LAME to the console whilst it encodes from the command-line. There are also GUI-based programs that can display that sort of information; EncSpot is the first that comes to mind, but other users may be able to advise on alternatives.

Is MP3 joint stereo the preferred mode?

Reply #11 –
if you're only going to listen on 2 speakers or headphones, JS.

i use either Windows/Drivers or FB2K's Channel Mixer to get surround sound on a 4 speaker setup, and at least as of the last time i tested it (3.90 thru 3.96 or so), you HAVE to use Forced Stereo.

essentially, if you have to ask, go with JS.