This update introduces a demux_packet_pool, allowing for the reuse of
previously allocated packets when needed.
sizeof(AVPacket) is not a part of the lavc public ABI, which prevents us
to allocate memory in larger blocks. However, we can substantially
decrease the amount of alloc/free operations during playback by reusing
both mpv's demux_packet and AVPacket.
This adjustment addresses the root cause of issue #12076, which,
although resolved upstream, did not fully tackle the persistent problem
of allocating small blocks of aligned memory. This issue largely stems
from the FFmpeg design of the AVPacket API. After this change memory
will no longer be allocated once cache limits is reached.
The demux_packet_pool is shared as a global pool of packets for a given
MPContext.
This change significantly speeds up the demuxer deinitialization,
benefiting file switching scenarios, especially when a large demuxer
cache is used.
See: #12294
See: #12563
Signed-off-by: Kacper Michajłow <kasper93@gmail.com>
