[FFmpeg-user] Source v210.mov has no interlacement info, ffv1 transcode is listed as progressive

[Tobias Rapp]

Hello Kieran,

On 28.07.2016 10:38, Kieran O Leary wrote:
> If I use -c copy to remux to mov or mkv, then the lack of
> interlacement info is maintained. When I encode with FFV1, using
> either MKV or MOV, the file is listed as progressive in mediainfo.
>
> However, the issue may not be specific to FFV1 as progressive values
> appear in mediainfo when using -c:v prores (in mov container) and
> libx264 in mov and mkv.

 From the top of my head FFV1 has a flag interlaced=false/true but there 
is no interlaced=unknown.

> Avid, even though I selected PAL top field first, did not
> write any interlacement info to the mov from what I can see. Nothing
> shows up in mediainfo in regards
> to interlacement for the source v210.mov, and I can't see any fiel
> atom info in mediatrace. Avid MC8 never seems to write field/aspect
> ratio in general for the 'send to QT' feature.

I guess on this list it might be helpful to use ffprobe for checking 
file properties. Example:

./ffprobe -show_streams -select_streams v \
   -show_frames -read_intervals %+1 some-file.mkv

> Seeing as -vf idet shows TFF values for these files, and the telecine
> machine that created these files outputs PAL TFF, I am tempted to just
> use field_order in the source file in order to correct this before
> transcoding,  but I thought I'd see what ye think anyhow in regards to
> this issue.

In my opinion it is better to detect and apply the 
interlaced/field_order properties early in the conversion chain. If it 
is left undefined the different tools in your conversion chain might use 
different internal defaults.

> [...]

Regards,
Tobias