makedip.py, bitc.py - add ffmpeg for DCP single reels

[hyz2993]

Still looking for ways for multi-reels.

Basic command line:
ffmpeg -i $mxf_1 -i $mxf_2 -c:a copy -c:v libx264 -pix_fmt yuv420p $output

Main difference:
DCP single reel includes two .mxf files as input. Current structure in makedip.py cannot recognise numbers of mxf in one directory. A change is made for it by sum([filename.count('.mxf') for filename in filenames]) == 2.
DCP proxies requires audio codec copying to the output instead of using aac codec, which is the general option in bitc.py. A change is made for it.

Also:
Split code for renaming proxy to a function in makedip.py.

I didn't figure out ffmpeg -map while it does stop audio codec copied to the output. So it's removed when running for DCPs.
using -map

Stream mapping:
  Stream #0:0 -> #0:0 (jpeg2000 (native) -> h264 (libx264))

-map removed

Stream mapping:
  Stream #0:0 -> #0:0 (jpeg2000 (native) -> h264 (libx264))
  Stream #1:0 -> #0:1 (copy)

[kieranjol]

Have you looked into the dcp scripts for this, like dcpaccess and dcpfixity? Just focusing on the mxfs doesn’t work the best as it only accounts for simple cases. You have to use the xml files in a dcp as your entry point and that tells you which mxfs to use, which order, and dcps can also have in and out points too, where the audio or video for each reel may not start or end with the first or last frame of data. And you have to account for the colour space issues too with the xyz source which i never quite figured out but it’s why that 3d LUT is in the scripts folder.

[hyz2993]

Thanks for the advice. It's true, while I think it's too complicated for checking too many sources just to make proxies for DCP. The command line provided from the document for making DCP proxies is ffmpeg -i $mxf_1 -i $mxf_2 -c:a copy -c:v libx264 -pix_fmt yuv420p $output, nothing about colour and start frame yet. I guess so far we can take this as an update, only if it won't make any error. And we will talk about the plan about a full service for DCP DIPs once we decide to work on that :).

[kieranjol]

You could also just update dcpaccess and if Args.dcp is used, it just calls dcpaccess. I spent so much time working on dcp scripts as you have to dig into the standard and test it against so many dcps as the standard has so much variety. Also if you use the xmls as your entry point, it will pretty much work for multi reel and single reel regardless.
Edit: dcpaccess was one of the very first scripts I wrote so it probably needs a lot of work, but there’s a lot in there to reuse as dcps are just so difficult.

[kieranjol]

Actually, it’s worth looking into easy dcps command line functionality as well. As the easydcp player is one of the best tools to make access copies of dcps. Dcpomatic also handles this now but not sure if it allows command line calls for this. There could be a series of fallback options. If easydcp installed, do a, if dcp o matic, do b, if neither, do your command or dcpaccess

[hyz2993]

They all sounds like very good advices! I should take a look at those scripts. Let me keep this pr on hold until I get something from Easy DCP and dcpaccess. Thanks!