[mythtv-users] trandcoding messes up 6 channel audio slow audio playback

[Gavin Hurlbut]

>> left_transcoded = left/2 + center/2;
>> right_transcoded = right/2 + center/2;

I have for nuvexport (in sox)
left_out   = left front   + (left rear - 6dB)   + (center - 3dB)
right_out = right front + (right rear - 6dB) + (center - 3dB)

I think this makes for a better downmix (if we can't use what myth
already has internally)

Oh, and
-6dB -> / 2 or * 0.5
-3dB -> / sqrt(2) or * 0.7 (approximately)