[FFmpeg-devel] [PATCH] fftools/ffmpeg_enc: Prevent duplicate A53 Closed Captions at frame rate up-conversion

Gyan Doshi ffmpeg at gyani.pro
Tue Jun 13 17:41:42 EEST 2023

On 2023-06-13 07:46 pm, Devin Heitmueller wrote:
> On Sat, Jun 10, 2023 at 11:55 PM Anton Khirnov <anton at khirnov.net> wrote:
>> I don't think there's a fundamental reason -r handling could not be
>> moved to lavfi, but it's a nontrivial task. E.g. the dup/drop counts are
>> integrated with the CLI and would have to be exported from lavfi somehow
>> if you wanted to keep that functionality.
> I think the big question here in my mind is:  does anyone actually
> care about the dup/drop counts?  I recognize it's a change in behavior
> for the application to not show that in the status, but how useful is
> it really to know that the app duplicated 50% of your frames because
> you put "-r 60000/1001" on the command line?

The dup/drop code is active in the absence of output `-r` if the output 
format is not VFR flagged.

Then the dup/drop count is useful to diagnose an abnormally large frame 
rate detected in the input stream,
such as a WebM with a 1k tbr or a cover image with a 90k tbr.
More mundanely,  one can check the 'CFR'-ness of a stream by looking at 
those counts, especially if lavfi is not present.


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