Cutting MXF file

[edo1080]

Hi, don't know if this is the proper section, but I am trying to write a tool which cuts an MXF file given the CPL entrypoint and duration data.

It depends on the essence (Video , audio or metadata) of course, but I know asdcplib has something useful in the code.

Is there a developer forum where I can discuss it?

[carl]

Hi,

There's no developer forum; here is fine if you want to talk about it.

[edo1080]

thank you for your kind reply,

The aim is to export one MXF file from DCPs which are splitted in reels, one MXF for video, one for audio and one for Atmos when present.

I've quickly read inside the ASDCP library, I'm focusing on Atmos which seems to be the hardest part, I have seen there's a method 'readframe', which should be supposed to read a portion of file corresponding to a frame. I siplmy wonder if the workflow I have to do is unwrap each reel and rewrap the whole joined essences in one big mxf reel, or read a portion of MXF file from byte x to byte y and join.

Thanks in advance

[carl]

I think you are right in your approach to use 'ReadFrame' to get the data, then write it out to a new MXF. Whether this will work for Atmos is anybody's guess, but one would guess that Atmos data can be chopped up like this.

If you want an off-the-shelf solution it should be possible to (ab)use DCP-o-matic to do what you want; make a project containing your DCP, keep the reel mode as "single reel" and it may give you what you want...

If you want to code your own thing, it might be worth looking at libdcp. This provides a slightly higher-level interface to DCPs than asdcplib.

[edo1080]

WOW, the off-the-shelf solution sounds the best one; but let's say the DCP is encrypted and I can provide a DKDM for it.

Can I import it in DCP O Matic and provide a DKDM for it? It's not clear to how to import and encprypted DCP in a new project...

I mean have I to import CPL, right and add DKDM for it, or first DKDM and then CPL? OK, will try... never thought about this solution


Edit: tested import of encrypted DCP and it works. Will try with the test DCP I mentioned before and report

[Carsten]

Can see no reason why this shouldn't work by simply importing a multi-reel DCP into DCP-o-matic, and exporting it as a one-reel DCP. For the ATMOS part, I don't know, I understand Carl has worked a bit on ATMOS (pass through) support recently, but don't know to which extent.

- Carsten

[edo1080]

Yes, it works with a standard DCP, I don't know about the atmos part, but I'll try and report here as soon as I have some time