Encoding Dolby Digital EX

[Blue_MiSfit]

Hi all,

Is there a free way to generate Dolby Digital EX streams from a 7.1ch source?

I see that encwavtoac3 (aften) can set the flag in the bitstream, but I don't see any way to feed it more than 6 channels.

Suggestions?

Thanks!
~MiSfit

[tebasuna51]

Try with:

in = WavSource("D:\Test\8_Channel_ID.wav")

ff = GetChannel(in, 1, 2, 3, 4)
bl = GetChannel(in, 5)
br = GetChannel(in, 6)
sl = GetChannel(in, 7)
sr = GetChannel(in, 8)

bc = MixAudio(bl, br) # by default 0.5, 0.5 the Back Center

bl = MixAudio(sl, bc, 0.5858, 0.4142)
br = MixAudio(sr, bc, 0.5858, 0.4142)

Mergechannels(ff, bl, br)

[Blue_MiSfit]

Interesting!

So, Dolby Digital EX is really just a very simple mixing of channels.

Doesn't this destroy the fallback 5.1ch presentation, though?

~MiSfit

[Blue_MiSfit]

Alright, so I'm generating a 5.1ch matrixed WAV, which I will then feed to encwavtoac3, and set the Dolby Digital EX flag on.

I also just got access to a Dolby DP600 encoder (sweet), and will feed it a 7.1ch interleaved WAV, and have it generate a Dolby Digital EX bitstream. We'll see what happens :)

~MiSfit

[tebasuna51]

So, Dolby Digital EX is really just a very simple mixing of channels.

The EX mix is intended to be played by a 6.1 system with a 6.1 source, then the Back Center is mixed in BL, BR to be compliant with max 5.1 channels in ac3 standard, and can be recovered by ac3 EX decoders.

With a 7.1 source my mix is only for a test.

Doesn't this destroy the fallback 5.1ch presentation, though?
Sorry, I don't understand the 'fallback' mean in this context.

[Blue_MiSfit]

What happens when you play a mix like this on a 5.1ch system