[FFmpeg-user] FFMPEG's MXF container support for DNxHR with Avid MC?

[Erik Dobberkau]

Hi Alan,

What should I expect in terms of being able to record or playback DNxHR in
> MXF containers using FFMPEG and the compatibility of those clips in major
> NLEs?
>

My personal take: Don't rely on anything. If you absolutely require using
Avid MC,
and there are major contraints, let MC do the conversion, and if something
is wrong,
you need to discuss this with Avid. It's nice there are tools out there
like ffmpeg,
or mxflib, or bmxlib, but in the end, when a vendor decides to do their own
thing
(see ProRes), I think it's "wrong" to expect open source projects to
address this.
There's always the option of hiring a knowledgeable developer to modify the
current
solution to fit your requirements.


> I see some support in FFMPEG source code (version 3.4) for DNxHR profiles
> in libavcodec but the libavformat MXF read/write code doesn't seem to have
> support for the new HR VCIDs (1270 - 1274), essence elements and other MXF
> container meta data for DNxHR and yet... FFMPEG can read it's own MXF files
> created with the DNxHR encoder. I'm guessing the MXF parser can read the
> files by using the VCID in the *frame* header and ignores the VCID in the
> MXF meta data/keys...
>

I'm expecting somebody will say "patch welcome" very soon... ;-)


> However, more importantly, the files do not "link" into Avid Media Composer
> (using the MXF AMA plugin.) Is this known to work for anyone else? I'm
> using MC version 8.8.1 (MacOS Sierra) and when I attempt to link the file
> there is an error message saying it cannot link but no console log entry
> saying exactly what it doesn't parse/like about the file.
>

It's been a while since I last checked, and I'm pretty certain I only did
that with
DNxHD, not DNxHR. Have you tried with DNxHD and had the same effect?


> I just need to know what works and what doesn't.
>

Some things do, some don't. In general the MXF wrapper is more a blessing
than a curse because it imposes many contraints on a file when being
written.
But this also means not only to write correctly encoded pixel data, but also
signaling the encoding parameters in the bitstream and the header correctly,
which is where many tools fail. All in all, your mileage will vary here.

Best,
Erik