DCP-o-matic converts 5.1 multichannel mix to 6 separate monos?

Anything and everything to do with DCP-o-matic.
Carsten
Posts: 2804
Joined: Tue Apr 15, 2014 9:11 pm
Location: Germany

Re: DCP-o-matic converts 5.1 multichannel mix to 6 separate monos?

Post by Carsten »

'Top of the screen'?

What type of cinema is this?

Usually you would have Left, Center and Right behind the screen, invisible, and, in general, vertically centred. There should not be a perception of sound coming from the top of the screen. Can you see speakers there? The only speakers visible in the auditorium should normally be side, back, and maybe top (ATMOS, Auro) surround speakers.

Any intermediate transfer, packing, formatting etc. will not change anything about the sound. If the DCP ingests and plays, it will be exactly what you created.

Keep in mind though, that when playing the Dolby 5.1 channel test, there will only be ONE signal at a time coming from a single speaker, so, speaker assignment is very obvious. In a realistic audio mix, it will usually not be so clear, depending on where your listening position is. Again, the surround in your mix is very subtle. Which is not necessarily wrong, as 'good' surround should not be a directional special effect, but should build an acoustic envelope around the audience.

I can give it a try in our cinema, but from what I already saw and heard on my home computer, it should be okay.


Did you create your piece as a SMPTE, or Interop DCP? That's a VERY far shot, but, you may try it in Interop as well.
Last edited by Carsten on Tue Oct 25, 2022 9:42 pm, edited 4 times in total.
Carsten
Posts: 2804
Joined: Tue Apr 15, 2014 9:11 pm
Location: Germany

Re: DCP-o-matic converts 5.1 multichannel mix to 6 separate monos?

Post by Carsten »

BTW - this is how a common cinema trailer looks like. LFE carries signal, and there's a lot more going on in the surrounds, but, that is what an action trailer is meant to be.
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Gorkem Sifael
Posts: 6
Joined: Mon Oct 24, 2022 1:16 pm

Re: DCP-o-matic converts 5.1 multichannel mix to 6 separate monos?

Post by Gorkem Sifael »

Hi Carl and Carsten,

So finally the new DCP I made by panning the channels in premiere myself worked. I guess either the 5.1 given to me was faulty or they figured their issue out in the cinema.

Regardless, I wanted to thank you for your kind support and making DCP-o-matic.
Jaume(Dolby)
Posts: 21
Joined: Thu Sep 22, 2022 7:54 am

Re: DCP-o-matic converts 5.1 multichannel mix to 6 separate monos?

Post by Jaume(Dolby) »

There is a typical question that I received by moviemakers last 30 years...

WHY MY DCP LFE & SURROUND SOUND SOFT IN CINEMA?
===============================================

Firt of all, must consider that listening in Theatre is NOT THE SAME that your saloon or your post studio.

Surround at cinema is aligned for a wide area with a lot of loudspeakers WITH SAME AUDIO at every side (except in Atmos).To avoid listening surround audio BEFORE screen channels, at cinema procesor is introduces time-aligning, a delay (30-70 ms), so listen the surround sound AT SAME TIME of screen....

This produces a secondary effect: IF SAME content is sended to Front and Surround. (as Upmix plugin), sound appear come from screen!!! but if you power-off the screen channels surround appear magically again... because is playing, but psicoacustincs referred to 340mts/second sound speed introduces a psicoacuustic different sensation. Remember that can be 80ms/2 FRAAMES of sync from 1st row and last row of the theatre....

Another factor is HOW is aligned your home/studio: if monitoring 5.1 with ALL CHANNELS AT SAME LEVEL (perhaps with Pink noise at 85db) as used in DVD/BR/NETFLIX etc, but.... in DCP/Theater you LOSS 3db because surround was aligned 3db LOW!!!

The sum of factors is the reason you see same modulation in Channels 1-2-3 (LCR) and 5-6 (Ls Rs) but when listen at Cinema if appear soft surround....
Similar that channel 6 (LFE). Broadcast Listening uses a Bass management extraction LFE from screen channels lower than 80Hz, but Cinema send to LFE the DCP Channel 6 only. this channel at theater is FULL BAND NOT FILTERED because understand you filter it in Cinema mix stage.....
Also the UPMIX plugin works nice for BROADCAST MIX, but for all reasons exposed before, not work as spected in a theater listening.

Finallly, but not a minor reason, listening curve is DIFFERENT than a home or small studio. Low and high frequencies use a different curve. mid/hi is not using a "tweeter" but a "horn" that sound more "aggressively" in 2-3Kz...

I am a fanatic supporter to people that creates shorts or indie movies, and offer regularly a CINEMA Certified audio studio all Saturdays to many shorts as "pro-bono" to make this small balance to already mixed content, before release DCP. With this 2 or 3 hours at studio, the difference is HUGE.

Why DOP not, for example, "push" this 3db UP the surround channels? because DO NOT KNOW if you mix your movie in a CINEMA STUDIO or in YOUR GARAGE STUDIO or even in YOUR KITCHEN -:) and how you aligned your monitoring surround...

So, my recommendation:
When mix surround audio for cinema, NEVER use a "up mix". Instead, SEND a TOTALLY DIFFERENT audio content to surround or even to screen... Never use a "stereo" tracks but a multiple mono tracks.... with no "phase" relation one to other...

search a CINEMA CERTIFIED MIX STUDIO near your home, and try to obtain a shoft session out of regular hours for free...
When you listen at studio that "replicates" conditions of a "REAL" Cinema!! Sure understand all I am talking about....
or WHY NEVER CAN PLAY "EQUAL" a mix not tested in Audio Cinema Studio...

Dolby Atmos is another history... if someone is interested to know how work,
tell me know and I can explain how is prepared the Atmos track of commercial movies.

Cheers
Jaume