[FFmpeg-user] Prores 444 being detected by quicktime as 422?

[Robert Krüger]

On Wed, Sep 12, 2012 at 10:33 AM, Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:
> On Tuesday 11 September 2012 10:04:07 am Robert Krüger wrote:
>
>> > It does not set the correct fourcc. It should be ap4h but it is apcn
>> > (which is the fourcc for prores 422). Quicktime and other apple
>> > software (like Final Cut) more or less blindly trust the fourcc. I
>> > tried overriding it with -vtag but that didn't work either:
>>
>> looking at the code, it looks as if Prores 4444 is not modeled as a
>> profile at all (see variable prores_profile_info), so it never sets
>> the correct fourcc.
>
> Thank you for analyzing this - I simply didn't understand the problem;-)
> (I couldn't believe it was not reported before and not tested originally.)
> Could you test attached patch? It contains some guessing.
>

I'll test the patch immediately. Just a quick update: I hacked the
codec not to override the fourcc if it is set on the command line and
the result was detected as Prores 4444 bei Quicktime but the alpha
information was lost. I verified by making a clip with alpha,
exporting it via final cut as prores 4444 and using the resulting clip
in a final cut sequence as an overlay, which worked. Then I transcoded
the exported clip using ffmpeg into 4444 using the hack and used that
clip as an overlay and alpha was gone. If a one-frame-sample of prores
4444 with alpha would help, I can make a trac issue and attach it.

I'll post the results of testing your patch next.

Regards,

Robert