[FFmpeg-devel] [PATCH v2 1/3] avformat/avformat: Deprecate AVFMT_ALLOW_FLUSH

[Martin Storsjö]

On Tue, 26 Sep 2023, Anton Khirnov wrote:

> Quoting Andreas Rheinhardt (2023-09-26 01:54:30)
>> It is of no value to the user, because every muxer can always
>> be flushed with a NULL packet. As its documentation shows
>> ("If not set, the muxer will not receive a NULL packet in
>> the write_packet function") it is actually an internal flag
>> that has been publically exposed because there was no internal
>> flags field for output formats for a long time. But now there is
>> and so use it by replacing the public flag with a private one.
>
> Is there any value for the callers in knowing whether flushing is a
> no-op or actually does something?

Hypthetically, in theory, I guess one could make a case for that. But most 
of the codepaths where one use this anyway, one is pretty closely tied to 
the specific muxer one is using (usually mov/mp4 or maybe mkv), so in 
practice I don't think that's needed.

I don't remember there being a specific demand for that back when this was 
added, it was only a case of us not having internal flags at the time.

Conversely, I guess we could google for AVFMT_ALLOW_FLUSH and see if 
there's any public third party code that shows uses of the flag. A quick 
googling didn't find any uses outside of ffmpeg itself, except for one 
example on stackoverflow where the flag seems to be used in an invalid 
way.

// Martin