3.0 surround mix. Channels?

[Pelvis909]

I'm trying to create a 3.0 surround mix DCP (L,R,C) without the proper equipment. I have made a master video file from Premiere Pro in DNxHD format with 4 audio channels, with the forth channel empty since its only possible to create files with even number of channels (2, 4, 6). When I import the file in DCP-o-matic it recognizes all four channels (with the forth empty when I look at the audio level graphs).
I then export

1. Before creating the DCP I got a warning message saying that fewer that 6 audio channels may cause problems in some projectors? Is this true? How?

2. DCP-o-matic also seems to be unable to create 3 audio channel DCPs so I made a 4 audio channel one with the forth (LFE) track empty. Could it cause confusion to the guy operating the projector if a track is empty?

3. Does it matter what is set the Default DCP audio channels to (Stereo, 4 channels, 5.1)?

4. When I try to check the DCP in NeoDCP player i can hear all the channels in my stereo system when i select Stereo or 5.1, but when I select mute all channels but L, R, C I can hear anything. How can I be sure the right audio is in the right channel in my DCP? Any other tips how I can test it?


Im obiously a beginner at this and have crappy equipment, so thanks for your help:)

[Carsten]

I don't know any DCI server that actually chokes on a DCP with less than 5.1/6 channels. Many commercial repertoire titles/classics are distributed in stereo worldwide.

I even know quite a few servers who tolerate no audio at all in a DCP. Some DOMs hints are just hints. Not everyone of them actually signals a real problem. And some of them should be revised from time to time to keep track of the current equipment. As keeping track of 150.000 installations worldwide is not easy, it is probably wise to be a bit conservative about hints and warnings. As you see, this one made you inquire on this forum - mission accomplished.

It is true however, that only an even number of channels is possible, and the unused channels simply have to carry silence. But DOM will not allow you to specifiy an odd number of channels anyway.

DOM will fill all unused channels with silence automatically. I suggest you choose the 6ch/5.1 config, and then L/C/R carries your audio, and the remaining three channels are silent. A projectionist will probably not even notice the empty channels.

The Default channel pref, as all the other prefs,. are just defaults that can be overridden any time in the GUI at their respective occurrence. I rarely do surround work, so I have my pref set to 2ch/Stereo. Whenever I create a 5.1 or 7.1, I use that setting under the DCP->Audio tab.

When I want to know what actually is IN a DCPs audio, I open the MXF audio file DOM creates in Audacity. Audacity allows to open MXF audio if the audacity FFMPEG plugin is installed. This will show all audio channels in the sequence they are laid out in the DCP. If you do that with the DCP you created, you should see channels 1,2,3 with audio, and the remaining channels with a zero line. It is then very easy to listen to them and mute them individually for a check.

You can also open the audio MXF right in DCP-o-matic and see what the matrix and the audio levels say.

- Carsten

[Pelvis909]

Thanks, good answers. I were actually able to open the DCP audio in Premiere again and see all the tracks and audio.
But why you suggest 6ch/5.1 with 3 empty tracks in this case and not just the 4 channel (L, R, C, LFE) option with one empty track?

[Pelvis909]

Thanks for good replies. Just one more question, why you suggest I choose the 6ch/5.1 config and have 3 empty tracks instead of choosing the 4ch (L, R, C, LFE) and get one empty track?

[Carsten]

Basic caution. DCPs are known to work on all systems in stereo and 5.1. I have never seen a feature in the wild with a 4 channel setup.

Also, there is no 4ch config currently in the DCNC:

http://isdcf.com/dcnc/home/appendix-4-a ... ation.html

I am pretty sure 4 channel will work, but for the above reasons, I would not recommend doing it.

- Carsten