[FFmpeg-devel] [PATCH] avcodec: add avcodec_reset_hw_frames_parameters()

[Thomas Guillem]

Or you can check the alternative patch: "avcodec/pthread_frame: rework assert"


On Thu, Nov 28, 2024, at 16:57, Thomas Guillem via ffmpeg-devel wrote:
> usage example:
>
>     AVBufferRef *hwframes_ref;
>     int ret = avcodec_get_hw_frames_parameters(ctx, hwdev_ref, hwfmt,
>                                                &hwframes_ref);
> ...
>     ret = av_hwframe_ctx_init(hwframes_ref);
>     if (ret < 0)
>     {
>         av_buffer_unref(&hwframes_ref);
>         avcodec_reset_hw_frames_parameters(ctx);
>         return -1;
>     }
>
> If avcodec_reset_hw_frames_parameters() is not called, it can lead to the
> following assert:
>
> Assertion p_dst->hwaccel_threadsafe || (!dst->hwaccel && 
> !dst->internal->hwaccel_priv_data) failed at 
> src/libavcodec/pthread_frame.c:426
> ---
>  libavcodec/avcodec.h | 15 +++++++++++++++
>  libavcodec/decode.c  |  5 +++++
>  2 files changed, 20 insertions(+)
>
> diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
> index 77ca8dee1f..dfea991db9 100644
> --- a/libavcodec/avcodec.h
> +++ b/libavcodec/avcodec.h
> @@ -2701,6 +2701,21 @@ int 
> avcodec_get_hw_frames_parameters(AVCodecContext *avctx,
>                                       enum AVPixelFormat hw_pix_fmt,
>                                       AVBufferRef **out_frames_ref);
> 
> +/**
> + * Reset AVCodecContext HW frames internals
> + *
> + * This function can be called after a successful call to
> + * avcodec_get_hw_frames_parameters() in order to reset the HW 
> decoding state.
> + *
> + * It can be used from get_format, to fallback to software decoding 
> after a
> + * failure, not necessarily linked to 
> avcodec_get_hw_frames_parameters()
> + *
> + * @param avctx The context which is currently calling get_format, and 
> which
> + *              implicitly contains all state needed for filling the 
> returned
> + *              AVHWFramesContext properly.
> + */
> +void avcodec_reset_hw_frames_parameters(AVCodecContext *avctx);
> +
>  enum AVCodecConfig {
>      AV_CODEC_CONFIG_PIX_FORMAT,     ///< AVPixelFormat, terminated by 
> AV_PIX_FMT_NONE
>      AV_CODEC_CONFIG_FRAME_RATE,     ///< AVRational, terminated by {0, 
> 0}
> diff --git a/libavcodec/decode.c b/libavcodec/decode.c
> index d1e10223f2..5e608076e5 100644
> --- a/libavcodec/decode.c
> +++ b/libavcodec/decode.c
> @@ -1227,6 +1227,11 @@ int 
> avcodec_get_hw_frames_parameters(AVCodecContext *avctx,
>      return ret;
>  }
> 
> +void avcodec_reset_hw_frames_parameters(AVCodecContext *avctx)
> +{
> +    ff_hwaccel_uninit(avctx);
> +}
> +
>  static int hwaccel_init(AVCodecContext *avctx,
>                          const FFHWAccel *hwaccel)
>  {
> -- 
> 2.45.2
>
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