[FFmpeg-devel] [PATCH] mxfenc.c: look for reel_name within streams as well

[Bartłomiej Styczeń]

I will report it right away. 

Timecode does not really go missing, it is written into the general metadata of the file instead of the video stream metadata.

Funny behaviour is that the patch in question, despite only fixing the reel_name, brings back the other remaining metadata into the video stream. I know next to nothing about MXF, this is also my first encounter with FFMPEG, but this smells like a broken linked list with a middle item not being written properly, hence the remaining ones disappear as well.

> On 6 Sep 2023, at 20:29, Tomas Härdin <git at haerdin.se> wrote:
> 
> ons 2023-09-06 klockan 12:16 +0200 skrev Bart Styczen:
>> If an MXF file has reel_name stored in a stream, while copying or
>> remuxing file, some (most) of the stream metadata is lost.
>> Here’s the file:
>> https://streams.videolan.org/ffmpeg/incoming/original.mxf
>> After running ffmpeg -i original.mxf -c copy output.mxf, and checking
>> with ffprobe, 
>> the original file has the following stream metadata:
>>>       file_package_umid:
>>> 0x060A2B340101010501010D431300000064F640280FA57031060E2B347F7F2A80
>>>       file_package_name: B002C0006_230803_1932_000001 (0)
>>>       track_name      : B002C0006_230803_1932_000001 (0)_v1
>>>       reel_umid       :
>>> 0x060A2B340101010501010D431300000064F640280FA67031060E2B347F7F2A80
>>>       reel_name       : B002C0006_230803_1932_000001 (1)
>>>       timecode        : 00:06:15:21
>> 
>> And the copied file only these:
>>>       file_package_umid:
>>> 0x060A2B340101010501010D001339242252947134203924220052947134203901
>>>       file_package_name: B002C0006_230803_1932_000001 (0)
>> 
>> 
>> After applying the patch, copied file correctly shows reel metadata
>> and the timecode:
>>>       file_package_umid:
>>> 0x060A2B340101010501010D001321CA09529471342721CA090052947134272101
>>>       file_package_name: B002C0006_230803_1932_000001 (0)
>>>       reel_umid       :
>>> 0x060A2B340101010501010D001321CA09529471342721CA090052947134272102
>>>       reel_name       : B002C0006_230803_1932_000001 (1)
>>>       timecode        : 00:06:15:21
>> 
>> 
>> The track_name is still missing though, so I will continue to
>> investigate the issue. 
> 
> Sounds like a mismatch in behavior between mxfdec and mxfenc. Timecode
> etc going missing suggests a deeper issue to which this patch is likely
> the wrong fix..
> 
> You should report this on trac if you haven't already
> 
> /Tomas
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