What's the best strategy to downmix audio (mainly 5.1 Dolby(c)) to 2.1 ?
Specifically: what tool(s) ? And what target codec ?
Any hints appreciated.
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I've never mixed for 2.1 before but I suppose that would just mean regular stereo plus an LFE (separate channel for sub woofer). And I have mixed surround into regular stereo before.
For tools, I think Audacity alone would be enough, but you might need plugins/realtime processing to effectively work with the tracks. Any multi track software would work like protools. I have no idea what target codec you want. Dolby digital can do any number of channels so maybe just stick with that and decrease the channel count.
As for specifics, I would just carry the LFE channel over as is, no reason to really mess with that. I'd also leave front-left, front-right and the center alone and hard pan them left/right/center, respectively. Watch out for any phasing or standing waves caused by the center channel mixing with the left and right. This could prove difficult to deal with if they deliberately put sounds on the center channel to prevent that from happening. Try some different things like inverting the wave or some EQ.
The rear left and right could also prove tricky. I wouldn't hard pan them as they are usually used for more ambient sounds that you probably want to wash around. I would try playing with a bit of reverb on them and maybe a gentle LPF since sounds from behind you usually have a bit of a cut in the highs.