gx
dcecd42de4
Snapshot FFmpeg n7.1 (release tag) с применённым patch'ем для cuframes input format. Используется как FFMPEG_REPO_OVERRIDE в NickM-27/FFmpeg-Builds fork для статической сборки patched binary под Frigate (Debian 12 / glibc 2.36). Apply changes: + libavformat/cuframesdec.c (новый — реализация демуксера) M libavformat/Makefile (CONFIG_CUFRAMES_DEMUXER target) M libavformat/allformats.c (extern declaration) M configure (--enable-libcuframes option + dep check) Patch source: https://git.goldix.org/gx/cuframes (filter/ffmpeg-7.1-cuframes-demuxer.patch) History сброшена (snapshot вместо fork) потому что upstream shallow clone не позволял push в gitea. Полная история FFmpeg — на github.com/FFmpeg/FFmpeg n7.1.
66 lines
2.7 KiB
Plaintext
66 lines
2.7 KiB
Plaintext
FFmpeg multithreading methods
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==============================================
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FFmpeg provides two methods for multithreading codecs.
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Slice threading decodes multiple parts of a frame at the same time, using
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AVCodecContext execute() and execute2().
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Frame threading decodes multiple frames at the same time.
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It accepts N future frames and delays decoded pictures by N-1 frames.
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The later frames are decoded in separate threads while the user is
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displaying the current one.
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Restrictions on clients
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==============================================
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Slice threading -
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* The client's draw_horiz_band() must be thread-safe according to the comment
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in avcodec.h.
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Frame threading -
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* Restrictions with slice threading also apply.
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* Custom get_buffer2() and get_format() callbacks must be thread-safe.
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* There is one frame of delay added for every thread beyond the first one.
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Clients must be able to handle this; the pkt_dts and pkt_pts fields in
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AVFrame will work as usual.
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Restrictions on codec implementations
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==============================================
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Slice threading -
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None except that there must be something worth executing in parallel.
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Frame threading -
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* Codecs can only accept entire pictures per packet.
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* Codecs similar to ffv1, whose streams don't reset across frames,
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will not work because their bitstreams cannot be decoded in parallel.
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* The contents of buffers must not be read before ff_progress_frame_await()
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has been called on them. reget_buffer() and buffer age optimizations no longer work.
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* The contents of buffers must not be written to after ff_progress_frame_report()
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has been called on them. This includes draw_edges().
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Porting codecs to frame threading
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==============================================
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Find all context variables that are needed by the next frame. Move all
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code changing them, as well as code calling get_buffer(), up to before
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the decode process starts. Call ff_thread_finish_setup() afterwards. If
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some code can't be moved, have update_thread_context() run it in the next
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thread.
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Add AV_CODEC_CAP_FRAME_THREADS to the codec capabilities. There will be very little
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speed gain at this point but it should work.
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Use ff_thread_get_buffer() (or ff_progress_frame_get_buffer()
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in case you have inter-frame dependencies and use the ProgressFrame API)
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to allocate frame buffers.
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Call ff_progress_frame_report() after some part of the current picture has decoded.
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A good place to put this is where draw_horiz_band() is called - add this if it isn't
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called anywhere, as it's useful too and the implementation is trivial when you're
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doing this. Note that draw_edges() needs to be called before reporting progress.
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Before accessing a reference frame or its MVs, call ff_progress_frame_await().
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