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From: Anton Khirnov <anton@khirnov.net>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Cc: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Subject: Re: [FFmpeg-devel] [PATCH v2 06/27] avcodec/vp9: Fix race when attaching side-data for show-existing frame
Date: Wed, 10 Apr 2024 09:06:58 +0200
Message-ID: <171273281857.22242.15680967665971235982@lain.khirnov.net> (raw)
In-Reply-To: <GV1P250MB073711693E037A6ED4C41C208F002@GV1P250MB0737.EURP250.PROD.OUTLOOK.COM>

Quoting Andreas Rheinhardt (2024-04-08 22:13:44)
> When outputting a show-existing frame, the VP9 decoder simply
> created a reference to said frame and returned it immediately to
> the caller, without waiting for it to have finished decoding.
> In case of frame-threading it is possible for the frame to
> only be decoded while it was waiting to be output.
> This is normally benign.
> 
> But there is one case where it is not: If the user wants
> video encoding parameters to be exported, said side data
> will only be attached to the src AVFrame at the end of
> decoding the frame that is actually being shown. Without
> synchronisation adding said side data in the decoder thread
> and the reads in av_frame_ref() in the output thread
> constitute a data race. This happens e.g. when using the
> venc_data_dump tool with vp90-2-10-show-existing-frame.webm
> from the FATE-suite.
> 
> Fix this by actually waiting for the frame to be output.
> 
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
> ---
>  libavcodec/vp9.c | 18 +++++++++++-------
>  1 file changed, 11 insertions(+), 7 deletions(-)

LGTM, though it'd be nice of someone more familiar with this decoder
looked at it.

-- 
Anton Khirnov
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  reply	other threads:[~2024-04-10  7:07 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-04-08 19:51 [FFmpeg-devel] [PATCH v2 01/27] avcodec/threadprogress: Add new API for frame-threaded progress Andreas Rheinhardt
2024-04-08 20:13 ` [FFmpeg-devel] [PATCH v2 02/27] avcodec/decode: Add new ProgressFrame API Andreas Rheinhardt
2024-04-09  1:40   ` Michael Niedermayer
2024-04-09  6:35     ` Andreas Rheinhardt
2024-04-10  7:01   ` Anton Khirnov
2024-04-10  7:09     ` Andreas Rheinhardt
2024-04-10  7:59       ` Anton Khirnov
2024-04-10  8:02         ` Andreas Rheinhardt
2024-04-10  8:06           ` Anton Khirnov
2024-04-10  8:09             ` Andreas Rheinhardt
2024-04-08 20:13 ` [FFmpeg-devel] [PATCH v2 03/27] avcodec/mimic: Switch to ProgressFrames Andreas Rheinhardt
2024-04-08 20:13 ` [FFmpeg-devel] [PATCH v2 04/27] avcodec/vp3: " Andreas Rheinhardt
2024-04-08 20:13 ` [FFmpeg-devel] [PATCH v2 05/27] avcodec/vp9: " Andreas Rheinhardt
2024-04-08 20:13 ` [FFmpeg-devel] [PATCH v2 06/27] avcodec/vp9: Fix race when attaching side-data for show-existing frame Andreas Rheinhardt
2024-04-10  7:06   ` Anton Khirnov [this message]
2024-04-08 20:13 ` [FFmpeg-devel] [PATCH v2 07/27] avcodec/vp9: Reduce wait times Andreas Rheinhardt
2024-04-08 20:13 ` [FFmpeg-devel] [PATCH v2 08/27] avcodec/vp9: Simplify replacing VP9Frame Andreas Rheinhardt
2024-04-08 20:13 ` [FFmpeg-devel] [PATCH v2 09/27] avcodec/vp9: Replace atomic_store() by atomic_init() Andreas Rheinhardt
2024-04-08 20:13 ` [FFmpeg-devel] [PATCH v2 10/27] avcodec/pthread_frame: Add API to share RefStruct refs just once Andreas Rheinhardt
2024-04-08 20:13 ` [FFmpeg-devel] [PATCH v2 11/27] avcodec/wavpack: Use ThreadProgress API Andreas Rheinhardt
2024-04-08 20:13 ` [FFmpeg-devel] [PATCH v2 12/27] avcodec/wavpack: Move initializing DSD data to a better place Andreas Rheinhardt
2024-04-08 20:13 ` [FFmpeg-devel] [PATCH v2 13/27] avcodec/wavpack: Only reset DSD context upon parameter change Andreas Rheinhardt
2024-04-08 20:13 ` [FFmpeg-devel] [PATCH v2 14/27] avcodec/wavpack: Optimize always-false comparison away Andreas Rheinhardt
2024-04-08 20:13 ` [FFmpeg-devel] [PATCH v2 15/27] avcodec/wavpack: Move transient variable from context to stack Andreas Rheinhardt
2024-04-08 20:13 ` [FFmpeg-devel] [PATCH v2 16/27] avcodec/vp8: Convert to ProgressFrame API Andreas Rheinhardt
2024-04-08 20:13 ` [FFmpeg-devel] [PATCH v2 17/27] avcodec/vp8: Mark flushing functions as av_cold Andreas Rheinhardt
2024-04-08 20:13 ` [FFmpeg-devel] [PATCH v2 18/27] avcodec/codec_internal: Remove FF_CODEC_CAP_ALLOCATE_PROGRESS Andreas Rheinhardt
2024-04-08 20:13 ` [FFmpeg-devel] [PATCH v2 19/27] avcodec/hevcdec: Switch to ProgressFrames Andreas Rheinhardt
2024-04-08 20:13 ` [FFmpeg-devel] [PATCH v2 20/27] avcodec/pngdec: " Andreas Rheinhardt
2024-04-08 20:13 ` [FFmpeg-devel] [PATCH v2 21/27] avcodec/ffv1dec: " Andreas Rheinhardt
2024-04-08 20:14 ` [FFmpeg-devel] [PATCH v2 22/27] avcodec/qsv: Use RefStruct API for memory id (mids) array Andreas Rheinhardt
2024-04-08 20:14 ` [FFmpeg-devel] [PATCH v2 23/27] avcodec/rkmppdec: Fix double-free on error Andreas Rheinhardt
2024-04-08 20:14 ` [FFmpeg-devel] [PATCH v2 24/27] avcodec/rkmppdec: Check av_buffer_ref() Andreas Rheinhardt
2024-04-08 20:14 ` [FFmpeg-devel] [PATCH v2 25/27] avcodec/rkmppdec: Use RefStruct API for references to decoder itself Andreas Rheinhardt
2024-04-08 20:14 ` [FFmpeg-devel] [PATCH v2 26/27] avcodec/rkmppdec: Allocate AVDRMFrameDescriptor and frame ctx jointly Andreas Rheinhardt
2024-04-08 20:14 ` [FFmpeg-devel] [PATCH v2 27/27] avcodec/v4l2_(m2m|buffers): Use RefStruct API for context references Andreas Rheinhardt
2024-04-09  6:33 ` [FFmpeg-devel] [PATCH v3 01/27] avcodec/threadprogress: Add new API for frame-threaded progress Andreas Rheinhardt
2024-04-10  6:38 ` [FFmpeg-devel] [PATCH v2 " Anton Khirnov
2024-04-18 20:40 ` Andreas Rheinhardt
2024-04-18 21:30   ` epirat07

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