[FFmpeg-devel] [PATCH] avformat/mux: skip parameter and pts checks for data muxer

[Nicolas George]

Gyan (12019-05-02):
> The flow is
> 
> avformat_write_header -> avformat_init_output -> init_muxer
> 
> And in the last function, lines 293-385 (as of 7eba26451) carry out the
> checks, and which my patch skips.

I missed this. My bad.

> The problem is that there is no clean set of flags which isolate the
> parameter-agnostic muxers - not surprising as this is a library for making
> valid media files. A new flag could be invented, if the present patch is too
> idiosyncratic. On a related note, as I mentioned elsewhere in this thread,
> an existing flag AVFMT_NOTIMESTAMPS, which in theory I could use, is of no
> help here, as it has been set for muxers which do handle timestamps in some
> way.

Yet, the name test is wrong: there are other muxers that absolutely do
not care about timestamps, or any other kind of parameters. The null
muxer, for starter.

I see a few options to make this work properly:

- Add an option "-noout" for ffmpeg to let it run without output, until
  the end of inputs. This would be useful for other situations,
  including cases when the log from filters is what the user is
  interested in. It would replace "-f null -" that we always use.

- Add an option "-mux_params_check 0" for ffmpeg output streams, tu
  allow skipping these tests explicitly. Your use case is specific
  enough that an additional option is acceptable.

- Create the required flags to mark muxers that do not require these
  tests.

Regards,

-- 
  Nicolas George
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