Dolby Digital vs. Dolby SR

danijel · 19th November 2008

I have heard different opinions on this subject, so I'd like to hear some more!

If a film is dialogue-driven, doesn't ask for great dynamic range, has minimal surround content (Amb, Music and Reverb) what would you suggest to a budget indie production? Would there be real benefit in doing a DD print, or would an optical SR print sound almost the same?

Since DD was incepted, optical sound has improved (better cameras, better reproduction), but how good is optical reproduction in average small theaters and how is it in big festival-theaters?

I was told by a theater-manager that digital sound 'soon' wears off, and that 'big portions' of sound that we hear in the theater is actually the (back-up) optical sound. Can anyone give approximations on how 'big portion' of sound comes from optical track after, say, 20 projections?

Thank you!

**Geert van den Berg** · 19th November 2008

It's either the digital or the backup that you're hearing. You can sometimes hear it switch if the print is worn.

quadraphonics · 19th November 2008

I have been to a few showings in the past few years where the DD track has switched to the SR. Granted, they were generally bigger budget action films (the bourne films, for example). There was an immediate drop in level and a narrowing of the sound field.
The frequency of a modern optical soundtrack can extend to approx. 14-16kHz. The dynamic range has to be limited, but for a dialogue driven film this would suffice.

georgia · 19th November 2008

For a budget Indie... just to Dolby Surround (LCRS)... it'll be fine. Printmaster it as an encoded stereo file. Note though, that DD is not amazingly more expensive.. you can get a festival license for just a few grand... and if you are mixing for LCRS you can always just print that as DD for better quality. But in reality... if the budget is that low, quality has probably already suffered so much that the audience probably wouldn't notice anyway.

cheers
geo

emf1138 · 19th November 2008

Quote:

Originally Posted by georgia

But in reality... if the budget is that low, quality has probably already suffered so much that the audience probably wouldn't notice anyway.

cheers
geo

LOL!! How true.

Branko · 19th November 2008

Most of the problems associated with DD playback comes from poor alignment of the reader head, as well as poor stability of the transport. First generation reverse scan readers on various projectors do not apply constant tension to film, so it "dances" up and down. Vertical position is critical for DD, the tolerance is (if I'm not mistaken) 2 mils! Add some sprocket hole wear, some lubricant + dirt accumulation on print = focus gone!
I've tested in my lab some prints that were returned by exhibitors as "Digital track worn out". All of them played back correctly on our Sondor Nova projector, and they have passed QC.
In a properly aligned system, Digital and Analog play back at the same level. Digital has some 10 dB more for headroom, if we assume that +4 dB (160% optical modulation) comes back from the analog optical recorder. Digital has an advantage that headroom exists on every channel, while analog applies to two, due to matrix encoding. Channel separation in Digital is absolute, while Analog tends to pull everything to centre. There's also a so called "steering effect" in Analog, where a strong signal on Left or Right tends to pull the whole front image to that side. Analog Surround is Mono and has a limited freq. response (up to 5K). It is also very noisy if not used moderately.
But, for a dialog driven film, these things would not be an obstacle.
Branko

bru95bg · 20th November 2008

SRD is better than SR. If you can do it I would go with that. Doing a 5.1 mix which can also be used for DVD and broadcast might also be a good thing to have even if you end up only print mastering a SR film track.

Even with a simple sound track a SRD print will have better imaging and signal to noise.

After 20 plays you should have a very small number of errors on the digital track.

Dolby would be able to offer you some good advice on this well -after all if the production is doing a Dolby mix then Dolbys part of the agreement is to help you get the mix from your mix-stage and into the cinemas sounding the way you mixed it.

Good film sound tracks can be made in both SR and SRD -SRD is better but if SR is all you've got you'll still be able to make it sweet.

Hope that helps.

Cheers

Bruno

juniperian · 20th November 2008

As an audio post facility owner who has done nothing for the last 12 years except for audio post on low budget indie features (close to 30 per year), I can tell you it's now not any harder to mix in 5.1 than LCRS. In fact, our workflow has become so exclusive to 5.1 that mixing in LCRS is a royal pain.

What my clients have found over the years is that it's MUCH easier to sell a film that's got the Dolby Digital logo on it, and that they can tell buyers is 5.1. So if it's not harder to do, and it's easier to sell, it's a no-brainer. The indie market is hard enough as it is. Why make it harder for yourself by not giving buyers the audio format they want?

If your track count is low, and your movie is mostly dialogue, then, no, most movie-goers won't notice a quality difference. But ya gotta sell the film in order for any movie-goers to see it in the first place.

Always go 5.1. If you can afford to make a film print, you can afford 5.1. Anyone who tells you otherwise is ripping you off.

19th November 2008	#1
danijel Lives for gear Joined: Jan 2008 Location: Belgrade, Serbia Posts: 1,732 Thread Starter	Dolby Digital vs. Dolby SR I have heard different opinions on this subject, so I'd like to hear some more! If a film is dialogue-driven, doesn't ask for great dynamic range, has minimal surround content (Amb, Music and Reverb) what would you suggest to a budget indie production? Would there be real benefit in doing a DD print, or would an optical SR print sound almost the same? Since DD was incepted, optical sound has improved (better cameras, better reproduction), but how good is optical reproduction in average small theaters and how is it in big festival-theaters? I was told by a theater-manager that digital sound 'soon' wears off, and that 'big portions' of sound that we hear in the theater is actually the (back-up) optical sound. Can anyone give approximations on how 'big portion' of sound comes from optical track after, say, 20 projections? Thank you! __________________ Danijel Milosevic

19th November 2008	#4
georgia Lives for gear Joined: Dec 2006 Location: NY NY Posts: 1,331	For a budget Indie... just to Dolby Surround (LCRS)... it'll be fine. Printmaster it as an encoded stereo file. Note though, that DD is not amazingly more expensive.. you can get a festival license for just a few grand... and if you are mixing for LCRS you can always just print that as DD for better quality. But in reality... if the budget is that low, quality has probably already suffered so much that the audience probably wouldn't notice anyway. cheers geo __________________ ms georgia hilton mpe(editor) mpse cas NY NY http://www.filmdoctors.com http://www.hiltonmediamanagement.com http://www.hmmproductions.com http://www.editingtruck.com http://www.stage32.com/profile/6569/georgia-hilton http://www.imdb.com/name/nm0385255/resume MEMBER: IATSE LOCAL 700

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19th November 2008	#2
Geert van den Berg Mac Moderator Joined: May 2003 Location: Amsterdam Posts: 3,454	It's either the digital or the backup that you're hearing. You can sometimes hear it switch if the print is worn.

19th November 2008	#3
quadraphonics Gear maniac Joined: Aug 2008 Posts: 152	I have been to a few showings in the past few years where the DD track has switched to the SR. Granted, they were generally bigger budget action films (the bourne films, for example). There was an immediate drop in level and a narrowing of the sound field. The frequency of a modern optical soundtrack can extend to approx. 14-16kHz. The dynamic range has to be limited, but for a dialogue driven film this would suffice.

19th November 2008	#6
Branko Gear addict Joined: Jun 2002 Location: Lisbon Posts: 335	Most of the problems associated with DD playback comes from poor alignment of the reader head, as well as poor stability of the transport. First generation reverse scan readers on various projectors do not apply constant tension to film, so it "dances" up and down. Vertical position is critical for DD, the tolerance is (if I'm not mistaken) 2 mils! Add some sprocket hole wear, some lubricant + dirt accumulation on print = focus gone! I've tested in my lab some prints that were returned by exhibitors as "Digital track worn out". All of them played back correctly on our Sondor Nova projector, and they have passed QC. In a properly aligned system, Digital and Analog play back at the same level. Digital has some 10 dB more for headroom, if we assume that +4 dB (160% optical modulation) comes back from the analog optical recorder. Digital has an advantage that headroom exists on every channel, while analog applies to two, due to matrix encoding. Channel separation in Digital is absolute, while Analog tends to pull everything to centre. There's also a so called "steering effect" in Analog, where a strong signal on Left or Right tends to pull the whole front image to that side. Analog Surround is Mono and has a limited freq. response (up to 5K). It is also very noisy if not used moderately. But, for a dialog driven film, these things would not be an obstacle. Branko

20th November 2008	#7
bru95bg Gear Head Joined: Nov 2008 Posts: 31	SRD is better than SR. If you can do it I would go with that. Doing a 5.1 mix which can also be used for DVD and broadcast might also be a good thing to have even if you end up only print mastering a SR film track. Even with a simple sound track a SRD print will have better imaging and signal to noise. After 20 plays you should have a very small number of errors on the digital track. Dolby would be able to offer you some good advice on this well -after all if the production is doing a Dolby mix then Dolbys part of the agreement is to help you get the mix from your mix-stage and into the cinemas sounding the way you mixed it. Good film sound tracks can be made in both SR and SRD -SRD is better but if SR is all you've got you'll still be able to make it sweet. Hope that helps. Cheers Bruno

20th November 2008	#8
juniperian Gear interested Joined: Sep 2007 Location: Burbank, CA Posts: 24	As an audio post facility owner who has done nothing for the last 12 years except for audio post on low budget indie features (close to 30 per year), I can tell you it's now not any harder to mix in 5.1 than LCRS. In fact, our workflow has become so exclusive to 5.1 that mixing in LCRS is a royal pain. What my clients have found over the years is that it's MUCH easier to sell a film that's got the Dolby Digital logo on it, and that they can tell buyers is 5.1. So if it's not harder to do, and it's easier to sell, it's a no-brainer. The indie market is hard enough as it is. Why make it harder for yourself by not giving buyers the audio format they want? If your track count is low, and your movie is mostly dialogue, then, no, most movie-goers won't notice a quality difference. But ya gotta sell the film in order for any movie-goers to see it in the first place. Always go 5.1. If you can afford to make a film print, you can afford 5.1. Anyone who tells you otherwise is ripping you off.