Quoting Thomas Guillem (2021-12-02 20:44:33) > > On Thu, Dec 2, 2021, at 15:05, Andreas Rheinhardt wrote: > > 1. hw_device_ctx is in the public AVCodecContext, not in the private > > AVCodecInternal. > > 2. ctx->internal is intended to be allocated for all the internal > > AVCodecContexts; the check is only there to ensure that we don't crash > > if an allocation error happens. > > 3. libavcodec only ever modifies avctx->hw_device_ctx at one place: in > > avcodec_close() where is unreferences the reference (if any). So if it > > was set in avcodec_open2() and NULL in avcodec_close() (i.e. immediately > > before avcodec_close()), it has been modified somehow and you need to > > find out who did it. > > 4. Some parts of the code use hw_device_ctx to derive references from > > it. Maybe one of these references did not get freed? > > (5. What do Valgrind/ASAN say? When was the reference that leaked created?) > > OK, all your point are valid, I missed a precious comment from the avcodec.h > API: > "For both encoders and decoders this field should be set before > avcodec_open2() is called and must not be written to thereafter." > > Hence, the incomprehension. > > So, to sum up: the reference that leaks is created from VLC, from the > get_format() callback. > Looking at pthread_frame.c, it seems that get_format() is called with a > AVCodecContext owned by a PerThreadContext, so not the main AVCodecContext. > That is why avcodec_close() is not closing it. > > I just discovered that it's not officially supported then, but I really don't > see any other way to plug VAAPI between VLC and ffmpeg. > > I explain: VLC can't know the hw_device that will be used when it calls > avcodec_open2(). VLC has a similar struct than hw_device, called dec_device. > For VAAPI, this struct hold the va_dpy that is created when the VLC avcodec > module first create the video output, from the get_format() callback. > > I see 2 possibilities: > 1/ Patch the documentation and allow to set a hw_device_ctx from > get_format(), review all use case of hw_device_ctx to check if there is no > inconsistency with this new change. > 2/ Use any other way to pass the va_dpy from the get_format()? I didn't see > any, but maybe I missed something obvious.
2. is the right answer - you're supposed to set hw_frames_ctx, possibly using the avcodec_get_hw_frames_parameters() helper function. -- 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".
