Audio Crackling

[swanpool]

I recently converted a Brain Farm Digital Cinema Reel 2012 from Vimeo to a DCP using DVD O Matic and found sections of the audio had a distinct crackle which was not in the original mp4 download.

After checking the DVD and DCP O Matic websites I re-encoded the file with the Audio gain set to -12db. This has eliminated the crackle.

However the crackle does not appear to be created by our cinema system which is a Barco 10s projector, Dolby DDSS220 Server/IMB and 7.1 Dolby CP750.

Rather the original crackle was present in the DCP when it was played using dcpPlayer on a PC. The cinema system was merely reproducing the DCP audio.

Crackling audio therefore appears to be an artifact of the DCP conversion process rather than the cinema audio system!

Is this a valid interpretation of what is occurring!

[carl]

Yes. If the audio level is too high it is clipped in the DCP's audio files, so it will sound nasty no matter what you play it back on.

[swanpool]

Thanks Carl. A great program and a real life saver for us at a small community run cinema in Victoria, Australia.
Peter.

[Mannix]

I'm hearing a popping/crackle in the louder sections of my short film's DCP when played in DCP Player as well. I don't have access to Q&C in theater, and want to clarify: Are you saying this crackle is only present when played on DCP-o-Matic Player and is not heard when played in theaters?

[Carsten]

I guess we need to get access to one of these audio files to see wether it is clipping or some sort of scrambling.

[Mannix]

Would that be the original sound files used to make the DCP or one of the mxf or xml files in the DCP?

[Carsten]

The audio mxf from the DCP. How long/large is the file?

One could load it into e.g. audacity and trim to parts where the crackling occurs, if it's too large. But you could also just convert a shorter area by trimming content in DCP-o-matic.