[FFmpeg-devel] [PATCH] lavfi/buffersrc: issue more specific error in case of invalid parameters

[Stefano Sabatini]

On date Wednesday 2023-03-01 15:33:51 +0100, Anton Khirnov wrote:
> Quoting Stefano Sabatini (2023-03-01 01:05:29)
[...]
> > BTW, I noticied this as part of debugging transcode.c (which looks
> > broken at the moment), since the timebase is read as 0/1 from the
> > decoder context, it would be a valid value when reading from the
> > AVStream (but this information is not copied by
> > avcodec_parameters_to_context). In decode_filter_video.c this is
> > indeed "fixed" by copying the timebase directly from the AVStream.
> > 
> > Is this expected? Shouldn't the timebase be copied to the decoder
> > context?
> 
> Historically, AVCodecContext.time_base for decoding was NOT (as one
> might expect) the timebase of input packets, set by the user. It was
> instead the inverse of the framerate stored in codec-level headers,
> which was called "codec timebase" by some documents.
> 
> Since that was massively confusing for pretty much everyone, I added
> AVCodecContext.framerate for exporting the framerate from the decoder,
> and deprecated the use of AVCodecContext.time_base for decoding
> entirely. After the recent major bump, time_base should not be used at
> all in any way when decoding.
> 
> The timebase of input packets should instead be stored in
> AVCodecContext.pkt_timebase. I suppose after some time has passed we
> might want to merge its functionality into time_base.

Makes sense, for the time being I understand the correct solution is to
use pkt_timebase. Thank you.