As categorised, this is a “working note” and explains how I ‘down mix’ quadrophic FLAC files into stereo files with the assistance of sox. This may well not be the best method and indeed I may be getting it totally wrong – who knows what two channels are supposed to go where?
It turns out that my portable media player doesn’t understand FLAC files with more than two channels, and as I have a number of these obtained from somewhere I needed a way to make them playable. The first step is to identify FLAC files with more than two channels. It turns out that the venerable file does that quite adequately :-
% file one.flac two.flac one.flac: FLAC audio bitstream data, 24 bit, stereo, 96 kHz, 24179840 samples two.flac: FLAC audio bitstream data, 24 bit, 4 channels, 96 kHz, 24179840 samples
As you can see the third column of the information about the file identifies the number of channels; it also identifies 5.1 surround sound files as 6 channel files. And quite possibly wilder and woollier kinds of channel numbers too.
Now onto the conversion. This is simply the following :-
% sox input-file.flac output-file.flac remix 1v0.5,3v0.5 2v0.5,3v0.5 norm % file output-file.flac output-file.flac: FLAC audio bitstream data, 24 bit, stereo, 96 kHz, 24179840 samples
The details of what sox command to use … and specifically the remix parameters came from a post discussing the problem here. I’m not qualified to assess the details, but the results seem fine. For extra points, the remix parameters for 5.1 surround sound are: 1v0.3694,3v0.2612,4v0.3694 2v0.3694,3v0.2612,5v0.3694.