stereo to 5.1

[jasonbond1100]

hello, how do we convert stereo to 5.1 and if we leave it stereo will it work in a cinema theater that has a 5.1 or will there be any empty blank channels left.
Pls help with the work flow thanks

[jasonbond1100]

if the input content is left and right audio. Do i select the processors alone or do i need to check box the upmix L and upmix R boxes green respectevly.

[Carsten]

The first item, number of channels and soundfield designator, only defines the number of audio channels of the resulting DCP. They do not cause any upmixing at all. If you want to expand a stereo source, you need to choose more than 2 channels there, AND select one of the upmixers/processors.

It mostly depends on your source audio charateristic. While 'real' cinema sound should be 'real' 5.1, or at least Left/Center/Right, if a stereo mix is all you have, it's okay to leave it stereo. You may choose 2-channel or 6-channel (5.1) in DCP audio properties then. Makes no difference in the cinema, 3-6 will be included, but padded with silence (which is okay).

Which of the processors you should try, again, depends on the audio type.

Is it mostly music in stereo - just leave it and don't use any audio processor (2-ch).
Is it the typical advertising mix - music in the background + a gluey voice, or a classic documentary, try the Mid-side decode. (4-ch). For a classic music + center voice, this upmixer is quite predictable. The 5.1 upmixers are experimental. You should only use them if you are able to preview your final DCP in a real cinema, as they may create undesirable results.

They only thing you should be concerned about is proper audio level. Every cinema is able to play even a mono/center only mix, no complaints.

- Carsten

---
The Processor control allows you to select a process to apply to the audio before it goes into the DCP. Three processes are currently provided:

Mid-side decode — this will take a L/R stereo input and extract the common part (corresponding to the ‘Mid’ in a mid-side signal) into the DCP's centre channel. The remaining L/R parts will be kept in the L/R channels of the DCP. This may be useful to make near-field L/R mixes more compatible with cinema audio systems.

Stereo to 5.1 up-mixer A — this will take a stereo input and up-mix it to ‘fake’ 5.1. The input L/R are treated as follows:
DCP L is input L bandpass-filtered between 1.9kHz and 4.8kHz.
DCP R is input R bandpass-filtered between 1.9kHz and 4.8kHz.
DCP C is input L mixed with input R, taken down by 3dB and then bandpass-filtered between 150Hz and 1.9kHz.
DCP Lfe is input L mixed with input R, taken down by 3dB and then bandpass-filtered between 20Hz and 150Hz.
DCP Ls is input L bandpass-filtered between 4.8kHz and 20kHz.
DCP Rs is input R bandpass-filtered between 4.8kHz and 20kHz.
This upmixing algorithm is due to Gérald Maruccia.

Stereo to 5.1 up-mixer B — this uses a different approach:
DCP L is input L.
DCP R is input R.
DCP C is input L + input R taken down by 3dB.
DCP Lfe is DCP C bandpass filtered between 20Hz and 150Hz.
DCP Ls and Rs are input L - input R with a 20ms delay.
---

[jasonbond1100]

Thanks Carsten for explaining in detail.
I have a left and right channel audio. Stereo mix. This is for a film to be screened in the Cinema. I need to have center audio as well. However they want a 5.1 audio. Is there a way i can have Left channel as left right. Right as right channel and centre i can have both left + right channel. Leaving the rest silent?
Center should be lowered -3db or -6 db?
Pls lemme know how can i set this up. Where do i make the changes.
thanks

[Carsten]

Hi Jason,

set DCP audio to 5.1

I would then try the Mid/Side decoder.

Adding L+R to the center channel is also possible. You can assign input channels to output channels multiple times. Right click on the matrix connection point, and you will see an option to lower level by -6 dB for L/R into Center.

- Carsten

[jasonbond1100]

Hi Carsten
Thanks so much
I have made a copy with the mid/side decorder as you mentioned.
And another copy I have is L and R for the Left Right channels. For the center channel I added L+R lowerd the levels with -6. For the Rear channels LS RS i have used L and R with a delay of 20ms.
I'll ask them to do a test run couple minutes just to see if it sounds alright.
I was just concerened about the rear channels leaving them silent so a friend told me that he used the L R channels with a delay for LS RS for documentary cinema screenings. Do you think this should be okay.
Thanks a lot

[Carsten]

Adding so much level to surrounds could turn out pretty bad. No one can force you to use surrounds if you don't want to or do not have anything in there.

Demanding a 5.1 DCP yes, but that doesn't mean there has to be something in the surround channels. Many OSCAR winning movies do not contain surround sound...

- carsten

[jasonbond1100]

Got it! Thanks Carsten