Any listening test Stereo vs Joint stereo in mp3? Options

[crazyman]

Hi all,

in many discussions I read about mp3 via Lame encoder the result is that the best solution is joint stereo. I believe in that as the developers who I highly esteem say so. But is this statement supported also by more independent listening tests? Especially I would be interested in comparison between --preset standard (joint stereo) and dtto with stereo mode.

Can the result in general depend also on the Lame version? From the tests I could read usually still the old good Lame 3.90.3 comes out as the winner.

Cheers,

Crazyman

[2Bdecided]

The stereo to joint stereo (i.e. L+R>M+S) transform is lossless and perfectly reversible. However, the channels are then lossily coded.

If you force an encoder to (a) stay in L+R mode (i.e. "discrete" or "true" stereo), and then (b) force it into a bitrate area where it will add audible distortion, the stereo image will be preserved but you'll have audible quantisation noise. If anything, the addition of poorly-correlated noise to both channels may make the stereo sound stage sound wider - artificially and quite nastily of course. The centre image could be damaged.

If you force an encoder to (a) stay in M+S mode (i.e. one of the options available in "joint" stereo), and then (b) force it into a bitrate area where it will add audible distortion, the stereo image will start to collapse and you may have audible quantisation noise, but it will be less obvious.

The point of VBR is to use as many bits are as necessary for a transparent result, and the point of joint stereo is to give the option of encoding M+S (or L+R!). You're only going to hear a difference between discrete and joint stereo if something goes wrong. Which it rarely does with lame 3.90.3 aps. What's more, of all the thousands of tracks that must have been encoded with aps, and the handful of tracks which are not transparent, no one has suggested that any of these are improved by forcing discrete stereo.

I'd encourage people to look at that thread...
http://www.hydrogenaudio.org/forums/index....showtopic=12004
...to see that forcing stereo may not be the answer - even when using a DPL or DPLII decoder.

Was this issue ever resolved?

Cheers,
David.

This post has been edited by 2Bdecided: Jan 17 2005, 16:38