[manolito]

This is a question for Tebasuna:

In AVStoDVD MrC uses downmix scripts from you. For downmixing 8ch audio to 6ch the script is this one:

Function Dmix86(clip a)
{
flr = Getchannel(a, 1, 2, 3, 4)
blr = Getchannel(a, 5, 6)
slr = Getchannel(a, 7, 8)
sur = MixAudio(blr, slr, 1.0, 1.0)
return MergeChannels(flr,sur)
}

Now over at VideoHelp JuMe proposed a different script:

The formula for 7.1 to 5.1 is a little more complicated:

Ls' = Ls + (-1,2 dB) × Lrs + (-6,2 dB) × Rrs
Rs' = Rs + (-1,2 dB) × Rrs + (-6,2 dB) × Lrs

In other words, surround back -channels are partially mixed together before they are combined with side surrounds. I’m a complete novice with Avisynth, so there is probably more sophisticated way of writing the script, but this is what I’ve been using:

Function Dmix8to6(clip a)
{
front = Getchannel(a, 1, 2, 3, 4)
bl = Getchannel(a, 5)
br = Getchannel(a, 6)
sl = Getchannel(a, 7)
sr = Getchannel(a, 8)
bl_new = MixAudio(bl, br, 0.8710, 0.4898)
br_new = MixAudio(br, bl, 0.8710, 0.4898)
sl_final = MixAudio(sl, bl_new, 1.0, 1.0)
sr_final = MixAudio(sr, br_new, 1.0, 1.0)
return MergeChannels(front, sl_final, sr_final)
}

Any comments?
I cannot really judge this script because I do not have a surround setup for audio (I'm old school - Stereo Only)


Cheers
manolito