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Topic: 4 Channel wav to mp3 (Read 3669 times) previous topic - next topic
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4 Channel wav to mp3

Hi, I hope this is the right section for my concern.

I'm going to encode a game soundtrack to mp3 with the newest LAME version (LAME 64bits version 3.99.2, --V 0 (-V 0 should give the best vbr quality, right? no -q switch needed anymore?).

My problem: Some of the tracks have more than 2 channel. Is there any way LAME downmix them to stereo or do I have to use another tool for it? Which is the best way to convert multichannel wav to max quality vbr mp3?

4 Channel wav to mp3

Reply #1 –
I think you'll need to use an audio editor to downmix.   

Audacty (FREE!!!) can probably do it.  I'm not sure exactly how to do it with Audacity, but, you'll probably have to split the multichannel file into individual mono tracks, and you might have to mix the left & right channels as separate mono files before re-creating a stereo file.

You can also try going direclty to Export, and Audcity might downmix automatically if you select a stereo format.

I think the Dolby default is to mix-in the rear surround and center channels at -3dB (the LFE is thrown away).    But in a Dolby Digital file, there is a metadata tag to set the mix-down levels.  (I don't know how to manually read that tag.)  And of course, you can use whatever mix ratio you want.

Mixing is additive and it will boost your left & right levels.    After mixing & saving, normalize your peaks to 0dBFS (or less) to prevent clipping (distortion). 

Quote
(-V 0 should give the best vbr quality, right? no -q switch needed anymore?).
That's correct.  The LAME Reference says: 
Quote
For the default VBR mode since LAME 3.98, the following table applies

-q 0 to -q 4 Use the best algorithm.
-q 5 to -q 9 Use the not so good algorithm


You've got to be a bit careful about saying "best".  MP3 is always lossy and if you can't hear the difference between V3 and V0 or 320 CBR, etc., you really can't say one is better or best.
 

4 Channel wav to mp3

Reply #2 –
To answer your first question, yes, no need to bother with the -q switch anymore.

Dunno if lame can do it on it's own, but SoX might be worth checking out.  You may have to convert from 4-ch wav > 2-ch wav, then encode to mp3 using lame.