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[bobkatz]

JamSync wrote on Sun, 30 October 2005 15:29

bobkatz wrote on Sun, 30 October 2005 18:23 The origin of the 3 dB down rule was to try to get a bit more mono compatibility and compatibility with Dolby Pro Logic which only has a mono surround. Compatibility with home music mixes at unity gain then becomes a sticky wicket. Sometimes I wonder if Dolby regrets having instituted the 3 dB down setup when they went to AC-3. BK No, there's a choice for decoding the surround levels that you consciously make when you encode for AC3. It depends on the target medium.

Right! I meant to say when they decided on the rule for surround levels when mixing for the theatre being 3 dB down in AC-3, if there had not been a Dolby SR/Pro Logic system preceding the digital system in the theatre I wonder if the 3 dB down thing would have occurred.

BK

[minister]

but i thought the Dolby Digital for theater creating the decibel equivalent of one acoustically summed screen channel in the rear (dropping it 3dB) pre-dates the Pro Logic business.  and Dolby instituted it for FILM THEATER reasons and not vis a vis a consumer format.

or am i wrong in that?

[JamSync]

minister wrote on Mon, 31 October 2005 01:16

but i thought the Dolby Digital for theater creating the decibel equivalent of one acoustically summed screen channel in the rear (dropping it 3dB) pre-dates the Pro Logic business.  and Dolby instituted it for FILM THEATER reasons and not vis a vis a consumer format. or am i wrong in that?

????

Dolby Surround preceded ProLogic decoding (a system that had better steering, but still was effectively Dolby Surround). Both preceded Dolby Digital...at least that's my understanding.


Here ya go. Check out the timeline on pp. 3-4.

http://www.dolby.com/assets/pdf/tech_library/2_Surround_Past .Present.pdf

[compasspnt]

JamSync wrote on Sun, 30 October 2005 17:01

I really hate to see Ilford stopping production of  black and white.

That is seriously bad news.

[JamSync]

bobkatz wrote on Mon, 31 October 2005 01:06

Right! I meant to say when they decided on the rule for surround levels when mixing for the theatre being 3 dB down in AC-3, if there had not been a Dolby SR/Pro Logic system preceding the digital system in the theatre I wonder if the 3 dB down thing would have occurred. BK

Yeah...it's like if my mom had accepted the job with Linus Pauling instead of marrying my father, who would I be?

[bobkatz]

JamSync wrote on Mon, 31 October 2005 00:06

Yeah...it's like if my mom had accepted the job with Linus Pauling instead of marrying my father, who would I be?

You'd be dispensing vitamin C instead of good audio advice?


BK

[iguana]

Hi minister,

minister wrote on Sun, 30 October 2005 23:33

in theory, you understand LtRt playback.  however, in the reality of projectors playing back a 2-channel encoded analog optical track, they have to decode it by means of a light passing through that portion of the film print. this is what is sent to the decoder.  this encoded SR is, as you well know,  distributed to the LCR, and mono S of the theater.  in the case of an LtRt on a Dolby print, it is created by the DMU of the 5.1 track feeds.  one issue that is important here is that there are silver and silverless (cyna or magenta dye) optical tracks, incandescent sensors cannot play back cyan dye tracks.  do you see the problem with playing back the encoding?

Yes, the site you mentioned explains the issue pretty thoroughly. But this is not an SR-specific problem, is it?

Quote:

what is confusing is Dolby uses SR (Spectral Recording) to mean noise reduction and SR (SuRround)...

Actually, as I learned from the Dolby docs, it means the same in both cases - the SR in film context refers to the fact that it's Dolby Stereo with added SR noise reduction.

Quote:

in order get an LtRt onto a film print, you have to go through an Official Dolby print mastering process.  this is the expensive part.  this matrixed 2 must be derived from the 6, at the printmastering session.  you cannot show up with a matrixed track to transfer to a film print.  also, the lab costs are at least $1000 more, and upwards for longer prints.  Dolby ASKS for $1000 for a License for under 30 minutes.  i can't remember what they want for the feature.  AFAIK, there are few Dolby rooms around, and they are often not cheap -- $300-$1000/hour. does that explain?

Yes, thanks again for the info (also to JamSync); I think we'll say good-bye to a SR-D print and do more research on the SR option. It seems there's a Dolby guy aswell as certified dub labs in Berlin, so at least getting the appropriate infos shouln't be a big problem.

[minister]

bobkatz wrote on Mon, 31 October 2005 09:24

JamSync wrote on Mon, 31 October 2005 00:06 Yeah...it's like if my mom had accepted the job with Linus Pauling instead of marrying my father, who would I be? You'd be dispensing vitamin C instead of good audio advice? BK

would those be SLOW response vitamins?  get it, C weighted?  

oh, sometimes i KILL me

iguana:

yes that site is about SR, matrixed 2channel that unfolds into vainglorious 4.0! LCR mono S.  LtRt, or Left Total Right total -- stereo is LoRo Left Only Right Only, and Z-axis playback is ZoRo.  and SoZo and SoHo and BoBo and HoMo and... as i adumbrated to in one of my posts, it is corn-fusing.  dolby use to call noise reduction (and still do, SR -Spectral Recording...)  your Ste-REO speedwagon Mix going to 35MM at a Lab:: it will have this types of Dolby A replacement Noise reduction: SR.

here is some poop:

Dolby Stereo (LCRS-->LtRt-->Dolby A encode-->OpticalTrack-->Dolby A decode-->LCRS) 4:2:4 matrix described above with Dolby A type noise reduction. Dolby A is no longer favored, instead use Dolby SR.

Dolby SR (LCRS-->LtRt-->Dolby SR encode-->OpticalTrack-->Dolby SR decode-->LCRS) 4:2:4 matrix described above with Dolby SR type noise reduction. This is the same as Dolby Stereo except that the optical track is encoded with SR instead of A type noise reduction. This format is still used for surround audio from film optical and as the backup track for Dolby Digital. The terms Dolby SR and Dolby Stereo are often interchanged, incorrectly.

Dolby Digital a.k.a. AC-3 5.1-->AC-3 data stream-->5.1 The compressed data stream supports up to 5 full bandwidth plus one low frequency effects channel. It is designed for film, broadcast, and DVD final audio delivery. It is NOT considered "editable", which means you cannot just "punch in" on the data stream without consequences. This is the digital audio part of Dolby SR-D and Digitial Cinema.

Dolby SR-D is a dual-stream audio delivery system printed on the film, with a Dolby SR optical track and blocks of bits printed between sprocket holes that, when reconstructed, form the AC-3 digital audio stream. Since both technologies (Dolby Digital and Dolby SR)are present on the same piece of film, the print will play in any theater, whether or not equiped with Dolby Digital equipment.   unless the projectionist is drunk!

hey, when is johhnny b gonna say that analog optical playback rules and dolby digital or DTS playback sucks?            

oh, and if the SR playback sucks, i can fix it with drastic EQ cuts!    

[minister]

jfrigo wrote on Sun, 30 October 2005 10:23

minister wrote on Sun, 30 October 2005 07:18 because you calibrate your Surrounds down 3 dB from the fronts (they add up to one screen channel) for film, not for TV or home DVD. 82 dB surrounds for Dolby Digital. I believe DTS stays at 85 dB in back.

hi there.  thought i'd resurrect this because i am about to do a DTS mix.

the DTS application Memo states that the surrounds are to be calibrated to 82 and the SUB to 88 (LCR are 85).  not 85 as stated here.

couldn't find this info at the site, but the place where i printmaster looked up this info for me.

...and let's see how long DTS stays around....

[Augustine Leudar]

jfrigo wrote on Thu, 27 October 2005 01:42

Level wrote on Wed, 26 October 2005 12:53 Two words.. Blue Sky http://www.abluesky.com/p_s_gb/p3s4s1.html I have to agree about Blue Sky for a budget system. It really is great for the money,

what is the money ? Cant seem to find a price quote and it doesnt say on their webpage....

[minister]

i have seen the 5.1 system for around $3700-$3900 USD

[Alécio Costa - Brazil]

So a set of Monitor Ones would be total sin?