5.1 Mix Encoding

[dulla]

Typically when doing 5.1 mixes, I've been submitting L,C,R,Ls,Rs, and LFE files separately to post houses. This time I need to encode the files myself for Blu Ray.

My question is: Do I need to create a separate downmix file in stereo (in addition to the surround ac3) or can the surround encoded ac3 file be played in a 2 channel stereo. Some receivers do downmixes, but I wanted to know if I am safe with one 5.1 ac3 file. Any insight to the process would help. I'll be using A Pack to encode the surround wave files. Thanks.

[hummer]

No separate stereo downmix required for dolby digital.

The question is, why use dolby digital for blu-ray? There are better options.

[danijel]

+1

Absolutely safe.

[pneyrinck]

Originally Posted by dulla

My question is: Do I need to create a separate downmix file in stereo (in addition to the surround ac3) or can the surround encoded ac3 file be played in a 2 channel stereo.

+1 for "no." Every Dolby Digital decoder is required to be able to down mix a 5.1 to stereo. That is a Dolby licensing requirement for all AC3 decoders.

Paul Neyrinck
Neyrinck Audio

[Etch-A-Sketch]

Originally Posted by hummer

The question is, why use dolby digital for blu-ray? There are better options.

Very good point!!! I noticed my blueray and sony home theater were doing "PCM Audio" (listed where it normally says Dolby Digital or Pro Logic on the receiver) the other night watching some blueray discs. I don't know what sampling rate it's at, but blueray can do uncompressed PCM audio... I thought that was pretty cool!

Not sure if there is still some sort of dolby downmix going on or if it's 6 discrete channels of PCM audio... but either way, it sounded pretty damn good!

[dulla]

Originally Posted by hummer

No separate stereo downmix required for dolby digital.

The question is, why use dolby digital for blu-ray? There are better options.

Thank you for your responses. Hummer, are there any good software encoders that you would recommend?

[soundboy]

Originally Posted by dulla

Thank you for your responses. Hummer, are there any good software encoders that you would recommend?

Ask Paul Neyrinc! Or just click his link.

[neilwilkes]

Originally Posted by pneyrinck

+1 for "no." Every Dolby Digital decoder is required to be able to down mix a 5.1 to stereo. That is a Dolby licensing requirement for all AC3 decoders.

Paul Neyrinck
Neyrinck Audio

Still a compromise though, really.
Much better to include a dedicated stereo stream if possible. AC3 downmixing is very primitive with just 3 possible values for C/Surrounds.

DTS-HD is a far better codec to use. If you use DTS-HD Master Audio, you get all in one stream for every DTS decoder. Plus it is a mandatory BD codec, so all players are required to be capable of decoding it.

[kk@jamsync.com]

Originally Posted by neilwilkes

Still a compromise though, really.
Much better to include a dedicated stereo stream if possible. AC3 downmixing is very primitive with just 3 possible values for C/Surrounds.

DTS-HD is a far better codec to use. If you use DTS-HD Master Audio, you get all in one stream for every DTS decoder. Plus it is a mandatory BD codec, so all players are required to be capable of decoding it.

Hi Neil,

Any development on the 5.1 LPCM/Blu-Ray front? From what I can tell, it's pretty much of a no-go at the moment with a lot of the cheaper authoring systems. What are you using for DTS-HD? I read about some problems vis a vis Encore with that.

My problem with DTS is that you need one setup for Blu-Ray and then a different one for broadcast. With the Dolby system, you've got both areas nailed.