[FFmpeg-user] Correct conversion of yuvj420p?

[Christian Ebert]

* Peter B. on Thursday, October 01, 2020 at 14:16:02 +0200:
> On 29.09.20 09:56, Christian Ebert wrote:
>> How about doing quick diagnosis with ffprobe before you start,
>> something like:
>>
>> ffprobe -v error \
>> -print_format default=noprint_wrappers=1:nokey=1 \
>> -select_streams V -show_entries stream=pix_fmt
>>
>> and make the command depend on the result?
>
> Thanks for the suggestion, but that actually is what I'm doing right
> now - yet it means to treat parts of the batches with different
> conditions/recipes.

I would be very surprised if you could use the same command on
thousands of videos.

> Additionally, in that concrete situation, the source videos (several
> thousand...) are stored on an S3-type object based storage (non-Amazon
> dialect). So used Mediainfo to avoid having to pull several hundred
> Terabyte of videos just to get their tech-MD.

What's wrong with that? But then again I don't understand: You
want to process _all_ the thousands of files, so you need them
anyway?

> And Mediainfo cannot tell me what FFmpeg considers yuvj420p, because...

If you can run Mediainfo on them (remotely?), I'd be surprised if
you couldn't run ffprobe on them - and if you haven't
built/installed ffprobe, even parsing `ffprobe -i input` lets you
detect the pix_fmt.

> Even if it wasn't for the "S3-extra-fun", I'm running into this issue
> every now and then in different video collections - and every "if -
> then - else" adds extra points of failure (and work).

I would think if - then - else is the way to _avoid_ points of
failure, but most likely I don't understand you setup and/or
intent, sorry.

Good luck.

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