Quoting Andreas Rheinhardt (2020-06-01 12:21:15) > Anton Khirnov: > > Quoting Andreas Rheinhardt (2020-05-29 18:31:57) > >> When a slice is encountered, the H.264 parser up until now always > >> unreferenced and reset the currently active PPS; immediately > >> afterwards, the currently active PPS is set again which includes > >> referencing it. Given that it is typical for the active parameter > >> sets to change only seldomly, most of the time the new active PPS will > >> be the old one. Therefore this commit checks for this and only > >> unreferences the PPS if it changed. > >> > >> Signed-off-by: Andreas Rheinhardt <andreas.rheinha...@gmail.com> > >> --- > >> New and much simplified version of [1]. This has been made possible by > >> 5e316096fa9ba4493d9dbb48847ad8e0b0e188c3. > >> > >> [1]: https://ffmpeg.org/pipermail/ffmpeg-devel/2019-August/248374.html > >> > >> libavcodec/h264_parser.c | 2 ++ > >> 1 file changed, 2 insertions(+) > > > > I've been considering a utility function along the lines of: > > > > int av_buffer_update(AVBufferRef **dst, AVBufferRef *src) > > { > > if ((*dst)->buffer == src->buffer) > > Obviously missing a check for *dst == NULL. > > > return 0; > > What if *dst and src point to different parts of the same underlying > AVBuffer? You'd need to overwrite **dst with *src in this case. > > > av_buffer_unref(dst); > > *dst = av_buffer_ref(src); > > return 1; > > Missing check for av_buffer_ref failure.
This was supposed to be a quick example, not complete code ready to be pushed. > > > } > > > > which would help avoid unnecessary unrefs+refs in such cases. Thoughts? > > > I also pondered such a helper function, but then opted for the simple > approach instead. But if you want such a function and if it resides in > libavutil/buffer.c, then one could improve this even further by not > calling av_buffer_unref(dst) which throws an AVBufferRef away, but by > just decrementing the refcount of the underlying AVBuffer of *dst (and > freeing it if necessary), incrementing the refcount of the AVBuffer of > src and overwriting **dst with *src. How is that an improvement? It seems like a lot of complexity to save a small malloc+free. -- Anton Khirnov _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
