24bit WAV file exceeds 4GB and won't save

[Jude]

I am trying to create an audio master for the DCP version of a film that is two and a half hours long. The mix is stereo, but because the audio needs to be 24bit (48k) the file sides exceeds the 4GB max allowed for a stereo WAV file. I'm new to DCP-O-Matic and this is the first time I've tried to create a DCP for such a long film. Obviously others must have come up against this issue before me, so if anyone has a suggestion for a workaround I would be very grateful to hear it!
Many thanks.

[carl]

Hi, the easiest thing is probably to split it into two parts and add them both to the DoM project one after the other. There should be no audible join so long as you are not asking DCP-o-matic to do any sample-rate conversion (i.e. if you're importing at 48kHz and the video frame rate is not being changed by DCP-o-matic).

Alternatively if you are mixing in 16-bit you could just import a 16-bit WAV and DCP-o-matic will convert to 24-bit for you.

[Carsten]

What applications do you use to create that audio master?


Standard WAV is always limited to 4GB in size, no matter if the filesystem supports larger files. Check wether your application supports other file types, Broadcast Wave, or Wave with RF64 extension.


BTW - a stereo file at 24Bit/48KHz computes to about 1GB per hour, so, 2-1/2 hrs should fit nicely into the 4GB limit. It becomes more of a problem with discrete multichannel files.

[Jude]

Am using Soundforge, and not sure why but you're right, its actually reporting the filesize in the software as just under 3GB but it still won't save.

With regards to saving as 16bit and letting DCP-O-Matic do the conversion, I had been led to believe errors in conversion are far less likely if the imported files were already in the correct bitrate, but if this is not the case then the 16bit solution would seem the best.

Would saving the left and right channels separately as two 24bit mono WAVs be any good?

[Carsten]

Yes, separate L/R monofiles work just as well, you only need to assign them to left and right in the audio matrix, per default or without special naming, mono files go to center.

It could be that the version of Soundforge you are using already limits to 2GB file size, that was another typical limit. I can find loads of GOOGLE hits about 2GB WAV file size limits, but must of them are very old. Still, some software may still impose that limit.
But it is also possible that the filesystem you are using imposes a limit.


The 16 to 24 Bit conversion in DCP-o-matic should cause no issues. Carl may comment wether DCP-o-matic uses straight requantization, or applies some interpolation or dithering in the process.

[Jude]

Thanks for your help. Decided to try the 16bit version and let DCP-O-Matic do the heavy lifting. So far so good! And can I also say that this program is awesome. It upscaled the 1080p video master to 2K with no difficulty, and I think it even looks better than the master!