surround sound in vegas at DVinfo.net

Baldwin Li · December 31st, 2007, 03:03 AM

hi folks,

i've almost finished the audio dubbing for a feature film - all the dialogue, atmos tracks, sound effects and music are laid out with a rough mix ready for a final mix. Incidentally i decided to do the dub in Vegas since i did the edit there as and it didnt seem worth the effort to do an export to protools or nuendo but im mighty glad of that decision as it has been absolutely fantastic for sound mixing.

Anyhow, the film is HD (shot on a Z1) so i'd like the final result to be in surround sound and on a blu-ray or HD DVD but only when the world catches up - initially it will be DVD with a stereo mix plus hopefully a surround mix. My question is, when burning a DVD do you have a completely separate surround sound mix from the stereo mix, or is the stereo mix just a summed version of the surround mix (with the inherent phase cancellation issues that may occur)? If anyone has had experience mixing surround sound in vegas and would like to share their thought that'd be most welcome.

cheers,

baldwin

Emre Safak · December 31st, 2007, 06:11 PM

It is sufficient to make a surround mix; the decoder can create a stereo mix from it. It is up to you (i.e., optional) to prepare a Dolby Surround (stereo) mix.

Peter Jefferson · January 1st, 2008, 06:02 AM

To detail Emre's response

Id have to say that providing a separate stereo mix would probably be your best option, however, as you're working on DVD to begin with then HD equivalents later, you can use the SAME AC3 file for both (HD and SD) depending on which authoring tool you use. Sadly, Vegas AVCHD with 5.1 encoding is rather weak and cheap and nasty IMO. I'm hoping this gets looked at for the next update.

Providing ONLY a 5.1 soundtrack is perfectly sufficient for most cases as the DVD player will downmix in a stereo output anyway... I'll explain:

You just need to make sure that the Pro Logic Mixdown Bitsream information (Bitstream Tab) is set to ON (i.e. turn on ProLogic Mixdown within the metadata) and ensure that the mix itself is running sufficient drops in Gain for surround and centre (-3 is default and perfectly sufficient).

Then within the Extended Bitream Tab, turn on the Surround EX mode to ensure that these downmixes are read properly from the DVD Player. As an aside for additional channels in an EX environment, this additional info plays a major role in compatibility, as some players can only read extended bitstream metadata. In any case, once the DVD player sees that its only outputting analogue stereo, it will use this data to downmix the entire piece and still sound clear and concise without puking your levels

As for stereo mixdown, be aware the dialogue normalisations behave differently in this kind of encode mixdown. (ie 5.1 master to stereo encode) with an excess of phasing a definite possibility, depending on the soundtrack and mix. By Encoding to Stereo from a 5.1 project, it WILL NOT yield the same results as a stereo mixdown during playback would, and it WILL NOT behave the way most people would assume. Instead, it is a far better option to create 2 entire mixes for each respective playback format.

Its best to read up on the Dolby white papers by heading to Dolby.com

Baldwin Li · January 9th, 2008, 12:00 PM

Thanks for the info emre & peter - sorry for the delayed response been away for the past week. Sounds like doing a 5.1 isnt as completely straightforward as i'd hoped... Im sticking to just a stereo mix for now i think, until i get round to doing that HD version i think. there isnt much in the film that really requires the surround speakers except a few background music type things and atmos effects.

cheers,

baldwin

Dave Blackhurst · January 9th, 2008, 03:06 PM

Baldwin -

Not quite sure what you're asking? I typically just set up surround for my project... when I render, I include a stereo audio (not sure it's needed? I just always add it so it's there for compatibility, Vegas mixes a stereo from the surround mix AFAIK). THEN, I just render an ac3 mix, and add it in as a second audio track in DVDA...

Maybe I'm missing something, but that workflow has worked fine for me, and I get pretty decent "you are there" sound for live events...

When shooting multicam, or if you're adding soundtrack or whatever, it's just a matter of positioning your audio where you want in the soundfield by moving the little dot around...

Allan Black · January 9th, 2008, 03:40 PM

Quote:

Originally Posted by Peter Jefferson

By Encoding to Stereo from a 5.1 project, it WILL NOT yield the same results as a stereo mixdown during playback would, and it WILL NOT behave the way most people would assume. Instead, it is a far better option to create 2 entire mixes for each respective playback format.

Emphatically agree. By doing 2 separate mixes you cancel any balance/phase/eq problems the might appear when it's too late in the schedule to fix 'em. Bad vibes (out of phase) with the client result, it's not worth it.

Last year I returned a few DVDs to the shop after we literally couldn't follow the dialogue buried in the stereo track of the movie.
Cheers.

December 31st, 2007, 03:03 AM	#1
Baldwin Li Regular Crew Join Date: Nov 2006 Location: Manchester Posts: 69	surround sound in vegas hi folks, i've almost finished the audio dubbing for a feature film - all the dialogue, atmos tracks, sound effects and music are laid out with a rough mix ready for a final mix. Incidentally i decided to do the dub in Vegas since i did the edit there as and it didnt seem worth the effort to do an export to protools or nuendo but im mighty glad of that decision as it has been absolutely fantastic for sound mixing. Anyhow, the film is HD (shot on a Z1) so i'd like the final result to be in surround sound and on a blu-ray or HD DVD but only when the world catches up - initially it will be DVD with a stereo mix plus hopefully a surround mix. My question is, when burning a DVD do you have a completely separate surround sound mix from the stereo mix, or is the stereo mix just a summed version of the surround mix (with the inherent phase cancellation issues that may occur)? If anyone has had experience mixing surround sound in vegas and would like to share their thought that'd be most welcome. cheers, baldwin

December 31st, 2007, 06:11 PM	#2
Emre Safak Trustee Join Date: Feb 2004 Location: Brookline, MA Posts: 1,447	It is sufficient to make a surround mix; the decoder can create a stereo mix from it. It is up to you (i.e., optional) to prepare a Dolby Surround (stereo) mix.

January 1st, 2008, 06:02 AM	#3
Peter Jefferson Inner Circle Join Date: Apr 2003 Location: Aus Posts: 3,884	To detail Emre's response Id have to say that providing a separate stereo mix would probably be your best option, however, as you're working on DVD to begin with then HD equivalents later, you can use the SAME AC3 file for both (HD and SD) depending on which authoring tool you use. Sadly, Vegas AVCHD with 5.1 encoding is rather weak and cheap and nasty IMO. I'm hoping this gets looked at for the next update. Providing ONLY a 5.1 soundtrack is perfectly sufficient for most cases as the DVD player will downmix in a stereo output anyway... I'll explain: You just need to make sure that the Pro Logic Mixdown Bitsream information (Bitstream Tab) is set to ON (i.e. turn on ProLogic Mixdown within the metadata) and ensure that the mix itself is running sufficient drops in Gain for surround and centre (-3 is default and perfectly sufficient). Then within the Extended Bitream Tab, turn on the Surround EX mode to ensure that these downmixes are read properly from the DVD Player. As an aside for additional channels in an EX environment, this additional info plays a major role in compatibility, as some players can only read extended bitstream metadata. In any case, once the DVD player sees that its only outputting analogue stereo, it will use this data to downmix the entire piece and still sound clear and concise without puking your levels As for stereo mixdown, be aware the dialogue normalisations behave differently in this kind of encode mixdown. (ie 5.1 master to stereo encode) with an excess of phasing a definite possibility, depending on the soundtrack and mix. By Encoding to Stereo from a 5.1 project, it WILL NOT yield the same results as a stereo mixdown during playback would, and it WILL NOT behave the way most people would assume. Instead, it is a far better option to create 2 entire mixes for each respective playback format. Its best to read up on the Dolby white papers by heading to Dolby.com

January 9th, 2008, 12:00 PM	#4
Baldwin Li Regular Crew Join Date: Nov 2006 Location: Manchester Posts: 69	Thanks for the info emre & peter - sorry for the delayed response been away for the past week. Sounds like doing a 5.1 isnt as completely straightforward as i'd hoped... Im sticking to just a stereo mix for now i think, until i get round to doing that HD version i think. there isnt much in the film that really requires the surround speakers except a few background music type things and atmos effects. cheers, baldwin

January 9th, 2008, 03:06 PM	#5
Dave Blackhurst Inner Circle Join Date: Feb 2007 Location: Apple Valley CA Posts: 4,874	Baldwin - Not quite sure what you're asking? I typically just set up surround for my project... when I render, I include a stereo audio (not sure it's needed? I just always add it so it's there for compatibility, Vegas mixes a stereo from the surround mix AFAIK). THEN, I just render an ac3 mix, and add it in as a second audio track in DVDA... Maybe I'm missing something, but that workflow has worked fine for me, and I get pretty decent "you are there" sound for live events... When shooting multicam, or if you're adding soundtrack or whatever, it's just a matter of positioning your audio where you want in the soundfield by moving the little dot around...