VF with another language from 23.976 mkv file

[gunnar]

Hi,
Now i have a blu ray that i am converting to DCP.
I have made MKV file with MakeMKV like i do all the time.

This blu ray have two languages and i need to be able to screen it with both languages.

Instead of transcoding two new separate OV´s i would like to transcoding this once and then make a VF with the other languages.
But now i am facing problem. The MKV is 23.976 fps and the DCP will be speeded up to 24fps witch is totally fine.
But then when i import the DCP back into DCP o matic and want to use the other language from the MKV to make the VF file the MKV file does not fit to the DCP since the DCP is now 24fps but the mkv is 23.976 fps.

So there is not much i could do to fix this?
Does it maybe solve the problem if i go into the timing tab and manually type in that this mkv is 24fps instead of 23.976fps?

[Carsten]

Hi Gunnar - yes, you need to adjust the reference frame rate under the Timing tab.

But - may I suggest a different workflow?

- generate the OV by selecting the first language in audio matrix. No further adjustments, DCP-o-matic will create 24fps DCP
- create another, temporary DCP from within the same project, this time selecting the second audio stream - just rename the DCP to tmp/spanish, whatever. Yes, it will take up some space, but will go very quickly, because the existing video is reused. (After this temporary OV is finished, you may immediately click 'Show DCP', then delete the new video.mxf).
- now, remove the mkv from your projekt, load the first language DCP, refer video to be used from this OV for VF, then load the audio mxf from the temporary OV with the second language. This will already be in 48kHz and will match the OV length. Then create the VF with the proper name.

I think this is the easiest workflow to create OV and VF from two language streams contained in a single mkv.

- Carsten

[gunnar]

Ok i am going to try that tomorrow.
So after the DCP is made i just simply changes the audio inside the project, edit the dcp name and hit again "Make DCP"
Are you sure that DoM wont just then transoce new DCP from scratch from the mkv file?
How does DoM know about the existing DCP if i just hit Make DCP after i have changes the langues and give it new name?

[Carsten]

As long as you stay in the same project, DCP-o-matic knows that you did not apply changes to the video part - so it assumes that for a new conversion, it can safely copy the existing video and just convert the new audio. That's the reason why there is a video folder in your project directory. DCP-o-matic keeps all the encoded frames there and copies or links them to the actual dcp folder. But this video folder is project specific, so this won't work if you create a new project - this will have it's own directory, and the video folder will no longer have the content encoded previously in a different project.


DCP-o-matic is pretty smart there - even if you add some subtitles to be burned in a second run, it will only re-encode the actual images where the subtitles appear, and copy the unaltered frames from the preexisting encoding.

https://dcpomatic.com/manual/html/ch05s03.html#idp6

You can create as many version of a dcp within the same project as you like. Just rename them under the DCP tab. This is very handy if e.g. you want to create versions with different audio levels for testing. Or different trimming, if you want to create some partial dcps for a screening.

Of course, this is just for time saving during the encoding, as this will always create a new OV that way. The time AND space saver then is using the OV+VF approach.


Regarding OV+VF from a multistream MKV, everything is covered here, but maybe it is actually a bit too much information...

https://dcpomatic.com/forum/viewtopic.php?f=2&t=997

- Carsten