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Topic: Lame 3.96 joint stereo problem? (Read 10184 times) previous topic - next topic
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Lame 3.96 joint stereo problem?

Reply #25 –
Quote
There is no reason why any DSP that wants to "fake surround" channels would have any issue with JS. JS doesn't affect phase information.

For all I can tell, your observations are based on your imagination running wild based on some very wrong misconceptions about how things work.
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No no no - we tested - don't you remember the thread?

If you listen to the difference channel in isolation, it's obvious that it is "bitrate starved" at some frequencies at some time. Totally inaudible in stereo listening, but totally obvious if you listen to L-R.

Most fake surround processing isn't going to choke on this, but you can't say that none will. The extreme case of just outputting L-R gives very audible artefacts.

[a href="http://www.hydrogenaudio.org/forums/index.php?showtopic=12004]http://www.hydrogenaudio.org/forums/index....showtopic=12004[/url]
(from the FAQ).

And plonk420's right - if (for some strange reason) you want to keep the difference channel "perceptually" intact, it seems that you might as well just use -m s. Unless the material is actually mono, it gives similar results to pushing nsmsfix to high values - which is the other (better?) option.


Motivo - for broadcast use, you should use lossless. In the UK, the BBC use lossless for their on-air playout system, while some commercial stations use 128kbps mp3 - guess which sounds better?

If lossless isn't an option, then for FM broadcast you should try to maintain as high a quality as possible in the lossy file (320kbps mp3 is a good choice), but low pass filter at 15-16kHz because FM stops here, and it's better to use the bits for lower frequencies that will be broadcast.

For digital broadcasting, you are effectively transcoding - it's better to start with a non-psychoacoustically based lossy format like Wavpack lossy etc at a similar kind of bitrate e.g. 300-400kbps. There are too many threads about transcoding here, but if you search for "transcode", posts by "den", you will find some interesting discussion.

However, if you can, use lossless.

Hope this helps.
Cheers,
David.