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Topic: DCP Digital Sound Formats Question

Carsten Kurz
Film God

Posts: 4340
From: Cologne, NRW, Germany
Registered: Aug 2009

posted 06-25-2012 08:06 PM

Lossless compression adds complexity and needs standards - all other DCP aspects use common standards - like Broadcast Wave Format for audio. Adding compression Is just not worth the effort. Lossless audio compression yields low compression ratios, like 2:1.

A typical 5.1 audio track in a standard feature will have something like 5GBytes of e.g. 150Gbytes total. What's the point in reducing this to 2.5Gbytes of 150Gbytes total? Most DCP shipping drives are larger than needed anyway, 320GB becoming a rare species.

- Carsten

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Scott Jentsch
Phenomenal Film Handler

Posts: 1061
From: New Berlin, WI, USA
Registered: Apr 2003

posted 06-27-2012 11:48 AM

For some reason, I was thinking that lossless compression was higher than 2:1, but some quick looking shows that I was mistaken.

Even though something like FLAC compression is a widespread standard, has MD5 hashes to ensure data integrity, and requires little decoding horsepower, it makes sense that the end result probably doesn't justify the effort.

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Bobby Henderson
"Ask me about Trajan."

Posts: 10973
From: Lawton, OK, USA
Registered: Apr 2001

posted 06-27-2012 12:59 PM

As others have said, lossless compression isn't necessary for the audio tracks on DCP hard discs. Storage space is ample.

I'm sure Dolby and DTS would have loved it if d-cinema employed lossless compression. Dolby and DTS would have had a chance to apply their TrueHD and DTS-MA compression schemes and brand names to the audio track. But that might have brought about yet another format war or created a situation where the DCP was carrying the movie audio track in both Dolby TrueHD and DTS-HD Master Audio. The dual inventory audio would eat up just as much disc space as an uncompressed LPCM soundtrack. The craziness might not even stop there. Dolby TrueHD and DTS-HD Master Audio are the most well known lossless surround sound formats for home theater. What if some jackass insisted the DCP carry dupes of the soundtrack in other formats like FLAC and Apple Lossless too?

Uncompressed linear PCM doesn't have a cool brand name and pretty much has a generic vibe. But it's more compatible than anything else. One thing I do wonder about is limitations from one d-cinema setup to another in handling high bandwidth LPCM, like 24-bit 96kHz audio or even 24-bit 192kHz.

If Dolby Atmos takes off in popularity that will make it necessary for the DCP to carry dual inventories of the audio (LPCM 5.1 and Atmos).

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Scott Jentsch
Phenomenal Film Handler

Posts: 1061
From: New Berlin, WI, USA
Registered: Apr 2003

posted 07-06-2012 12:54 PM

It's unfortunate that some sort of de facto moniker is not attached to it, so that it would be easy to market. It's somewhat ironic that the most superior sound format available has no marketing attached to it, effectively blunting its marketability.

Even if it was called what it is, it would be something. Some theaters were inserting it into the notes on their showtimes as LPCM 7.1 or PCM 7.1, but none are right now. (Only two theaters are advertising ATMOS)

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Jonathan Goeldner
Phenomenal Film Handler

Posts: 1360
From: Washington, District of Columbia
Registered: Jun 2008

posted 07-06-2012 05:07 PM

quote: Scott Jentsch
I knew that the audio was PCM, but I'm surprised that it is not losslessly compressed in any way.

Maybe they feel that there's more hard drive space right now than there are CPU cycles to decode a compressed stream, but I see this as something that will most likely change in the foreseeable future.

in terms of the lossless audio, the audio/soundmix of 'Saw 3D' was exceedingly dynamic - during the ear assaulting car explosion I literally thought the speakers blew as well. The underwater quake in 'Piranha 3D' it actually sounded like a ceiling brace in the auditorium had cracked too - it was both startling AND scary. The wide dynamic range that DCP's can deliver is outstanding in my opinion.

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Ron Funderburg
Jedi Master Film Handler

Posts: 814
From: Chickasha, Oklahoma, USA
Registered: Nov 2007

posted 07-06-2012 05:21 PM

Scott most places market the sound by what the processor is that is being fed to. If the processor is Dolby then they say it is Dolby Sound if it is a DTS unit it is advertised as either DTS or Data Sat. I guess Dolby has come out with a new system but it isn't in many markets yet. I don't even know if there is a separate audio file for the new Dolby.

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David Graham Rose
Expert Film Handler

Posts: 187
From: Cambridge, UK
Registered: Sep 2002

posted 07-07-2012 02:11 AM

Greetings All

I believe Bobby is mistaken with regard to the Atmos system. The whole point of Atmos is that dual inventory DCP's are not needed, and metadata is used to control the system which can be encoded onto a standard DCP with a 5.1 or 7.1 mix (which incidentally is generated from the Atmos mix). Or at least that's my limited understanding. Also for all those interested, I had my right foot amputated on Thursday following an incident with my former wife's lawnmower. The grass in the garden is now long, and I am a little lopsided. Can anyone make an "extension platform" to my right shoes?

From a wet Cambridge, I bid you Goodmorning

David.

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Ron Funderburg
Jedi Master Film Handler

Posts: 814
From: Chickasha, Oklahoma, USA
Registered: Nov 2007

posted 07-07-2012 10:06 AM

David sorry to hear that hope you have quick recovery and get a good prosthetic (sp).

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David Graham Rose
Expert Film Handler

Posts: 187
From: Cambridge, UK
Registered: Sep 2002

posted 07-07-2012 01:30 PM

Greetings to you Ron

I'm not that worried about that foot anyway as the arthritis was pretty bad in it as well and had long lost the feeling in my toes as well, so not too much of a disaster! I'll live to research further topics of interest! I suppose it's quite apt whist on the topic of Atmos and DCP's: Single inventory - good (i.e. my remaining foot); Dual inventory - bad (Thursday morning before the accident)!.

From a wet Cambridge, I bid you Good Evening.

David

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Ron Funderburg
Jedi Master Film Handler

Posts: 814
From: Chickasha, Oklahoma, USA
Registered: Nov 2007

posted 07-07-2012 01:34 PM

I had major emergency (almost died) surgery on the 3rd of may. The recovery has been slow since it was a full open up your gut. Getting back to normal but have to follow restrictions until sometime in August. Can't tell you how hard it is not to go up the stairs to the booth.

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David Graham Rose
Expert Film Handler

Posts: 187
From: Cambridge, UK
Registered: Sep 2002

posted 07-08-2012 02:26 AM

Greetings Ron

Get well soon I say! And don't overdo it. I've just hired a gardener.

David

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Yinghong Wu
Film Handler

Posts: 32
From: Suzhou Jiangsu China
Registered: Apr 2012

posted 07-09-2012 03:09 AM

I use OpenDcp to make the DCP,The sound format I use is 24bit,48KHZ,linear PCM audio.

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Jonathan Goeldner
Phenomenal Film Handler

Posts: 1360
From: Washington, District of Columbia
Registered: Jun 2008

posted 07-09-2012 10:13 PM

didn't I read somewhere recently that Dolby is trying to get the studios/mixers to encode sound at 96khz ?

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Jock Blakley
Expert Film Handler

Posts: 218
From: Melbourne, Victoria, Australia
Registered: Oct 2011

posted 07-10-2012 02:46 AM

The DCI standards do allow for 96 kHz sound in DCPs but it's up to people to use that capability.

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Michael Brown
Phenomenal Film Handler

Posts: 1522
From: Bradford, England
Registered: May 2001

posted 07-10-2012 05:57 PM

quote: Scott Jentsch
It's unfortunate that some sort of de facto moniker is not attached to it, so that it would be easy to market. It's somewhat ironic that the most superior sound format available has no marketing attached to it, effectively blunting its marketability.

Even if it was called what it is, it would be something. Some theaters were inserting it into the notes on their showtimes as LPCM 7.1 or PCM 7.1, but none are right now. (Only two theaters are advertising ATMOS)

One of the large chains on the UK is advertising it as Dolby 'Profound Sound'

..and if you read the blurb on their website is seems to suggest as well as making up the name they also seem to take credit themselves for the mix.

"Breatht4King Vue is further enhanced with Vue Profound Sound, in stunning Dolby 7:1 sound. Vue's unique and professionally mixed sound will make cinema goers feel like they are part of the action"

When in doubt just make something up. [Big Grin]

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