[FFmpeg-user] DNxHD / DNxHR conversions for Avid

[Media Mouth]

> On Apr 12, 2022, at 12:24 PM, Paul B Mahol <onemda at gmail.com> wrote:
> 
> On Tue, Apr 12, 2022 at 2:13 AM Media Mouth <communque at gmail.com <mailto:communque at gmail.com>> wrote:
> 
>> We've got a bunch of mp4s that need converting to Avid-native MXF that
>> they can be dropped into a ../Avid MediaFiles/MXF folder without being
>> ingested.
>> (In other words, bypassing the need to importing/transcoding and avoiding
>> using AMA+transcoding)
>> 
>> The mp4 sources are 29.97, 23.976 and 25fps (at 3840x2160)
>> The Avid project is DNxHD36 1920x1080 @ 24fps, and the mandate is to not
>> mix frame rates on the timeline.
>> 
>> So the current workflow involves using Resolve, where we select the mp4s
>> and Clip Attributes > Video Frame 24
>> then throw onto a timeline and export using format MXF Op-Atom using Codec
>> DNxHD 1080p 36 8bit video
>> That generates files that can be drag and dropped to Avid Media folders
>> which then show up in bins via importing the msmMMOB.mdb (per folder media
>> database)
>> 
>> I'm trying to achieve the same Avid-compatible MXFs using FFmpeg
>> So far I haven't figure out how do DNxHD w/o getting an error in FFmpeg
>> And my attempts to do DNxHR, while successful in terms of getting a
>> playable file and no errors on the FFmpeg,
>> do cause an error on the Avid side if you drop them directly in an Avid
>> MediaFiles/MXF folder
>> 
>> 
>> Most successful FFMPEG command (the one that resulted in the above error)
>> so far has been this...
>> 
>> ffmpeg -i /path/to/source.mp4 \
>> -c:v dnxhd \
>> -vf 'scale=1920:1080,fps=24/1,format=yuv422p' \
>> -profile:v dnxhr_lb \
>> /path/to/dest.mxf
>> 
> 
> I see nowhere here presentation of the error, either ffmpeg one or avid one.
> 
> Do note that ffmpeg's mxf muxer is not very polished in current version.

Thanks Paul

> RE "not very polished":

Noted.

> RE FFmpeg error

I managed to get past the DNxHD error using the following CLI

ffmpeg -i /path/to/source.mp4  \
-c:v dnxhd \
-vf 'scale=1920:1080,fps=24/1,format=yuv422p' \
-b:v 36M \ 
/path/to/dest.mxf

...so I'm able to create a DNxHD and DNxHR of the mp4 in an MXF wrapper
But neither works in Avid as hoped -- at least not yet.

> RE: not seeing the attachment jpg showing the error...

It was definitely included in the prior email, so I'm not sure why it didn't arrive.
Attaching it again, hoping it does this time.
But just in case it doesn't, here's the error dialog that pops up:
"Exception 'LocalMDB::ScanMXFFileToMobManager - Invalid data stream offset'"
"An error occurred scanning the file Avid MediaFiles/MXF/path/to/file"

Button options in the dialogue box are "Abort" "Quarantine" "Quarantine All" "Ignore" "Ignore All"