Media shows offline from a python-generated AAF file

[corentincharron]

Hello,

For our internal CG pipeline I am writing a little script which rebuilds an edit with OTIO and exports if as AFF.

Currently, when I import the generated AAF into Premiere all my clips are brough in as offline files, and I don't know why.

I initially though it was due to UNC paths (footage are located on a network space), but after trying to mount my network location to a drive letter, the problem remained, so I ruled out this hypothesis.

I am just discovering otio, and finding the learning curve quite steep, so bare with me, it is certainly not a bug, definitely an error on my side, but any help would be very appreciated.

Here is a minimum reproducible example of how I build by AAF file:

from pathlib import Path
import opentimelineio as otio


sources = {
    "//my/network/location/shot1.mov": 55,
    "//my/network/location/shot2.mov": 26,
    "//my/network/location/shot3.mov": 71
}

timeline = otio.schema.Timeline("Demo")
track = otio.schema.Track(f"V1", kind=otio.schema.TrackKind.Video)
timeline.tracks.append(track)

for path, duration in sources.items():
    path = Path(path)
    clip = otio.schema.Clip(name=path.name)
    clip.media_reference = otio.schema.ExternalReference(
        target_url=otio.url_utils.url_from_filepath(path),
        available_range=otio.opentime.TimeRange(
            start_time=otio.opentime.RationalTime(value=0, rate=24),
            duration=otio.opentime.RationalTime(value=4, rate=24)
        )
    )
    track.append(clip)
destination = "//my/network/location/export.aaf"
otio.adapters.write_to_file(timeline, destination, adapter_name='AAF', use_empty_mob_ids=True)

Thank you for any help :)

[apetrynet]

Hi, @corentincharron

I don't have a direct answer to your question, but thought I'd point you to this resource. It might give you some answers.

[timlehr]

Hey @corentincharron,

Is the file you're building actually just setting its target_url to a .mov file? I would expect it to be another .aaf for each shot or at least an .mxf. I believe when you use the later, you'll also have to provide the MobID for each video in the metadata, since Media Composer can't connect the dots otherwise.

[peter-targett]

Is the file you're building actually just setting its target_url to a .mov file? I would expect it to be another .aaf for each shot or at least an .mxf. I believe when you use the later, you'll also have to provide the MobID for each video in the metadata, since Media Composer can't connect the dots otherwise.

This is my experience - using MXFs and setting the MobID in the metadata does produce media that's online in Media Composer but only when you've brought the media online with menu option File > Media > Load Media Database.

[peter-targett]

punchline.zip

Been looking at this issue again and wonder if I'm missing something obvious, and whether there is a test case or example that does work?

In Media Composer, if I take one .mov file (from ASWF samples), transcode it to an MXF file, add it to a sequence in Avid and export an AAF I'm able to conform this in an NLE (like Baselight) using the Avid UID (MobID).

If I now try a round-trip with otioconvert -i punchline.aaf -o punchline.otio followed by otioconvert -i punchline.otio -o punchline2.aaf then punchline2.aaf should conform and link the media via Avid UID? It doesn't.

Also tried just the second part of the above, creating a simple otio file with the required AAF SourceID metadata entry, manually adding the MobID from referring to the MobID that was used and did link the media in the NLE. However this does not link the media.

I guess my first question is is there something missing in my understanding, and is there a working example?

I tried all the above with the older 1.1.0 version of the adapter code, and with the recent update to 2.0.0 (#44).

[jminor]

I just checked our pipeline to see how we handle this at Pixar. We're using Avid Media Composer, not Premiere and we use AAFs instead of MXF for the media, so some of the details may be different.

Our system generates a separate AAF for each media clip (equivalent to your MXFs) and then we relink the clips in the OTIO composition to point each of those AAFs before calling otioconvert (using prefer_file_mob_id=True) to turn that OTIO into an AAF. This causes the AAF adapter to peek at each of those AAFs to find the MobID and available range for each clip.

We then import those media AAFs and the composition AAF into Media Composer. In future, we will take advantage of Media Composer's OTIO import feature, but we haven't rolled that out to our editors yet.

I agree it would be great to have a working example of this with sample data.

[peter-targett]

Our system generates a separate AAF for each media clip (equivalent to your MXFs) and then we relink the clips in the OTIO composition to point each of those AAFs before calling otioconvert (using prefer_file_mob_id=True) to turn that OTIO into an AAF. This causes the AAF adapter to peek at each of those AAFs to find the MobID and available range for each clip.

I can see how that works right now. Looking into the adapter I think it may require more metadata for it to create a media-linkable AAF from a straight .otio file, that's my hunch at least. Will investigate, and create a separate issue/pull if when this works.