[FFmpeg-devel] [PATCH] libavcodec/vp8dec: fix the multi-thread HWAccel decode error

Carl Eugen Hoyos ceffmpeg at gmail.com
Wed Mar 6 09:48:33 EET 2019


2018-08-09 9:09 GMT+02:00, Jun Zhao <mypopydev at gmail.com>:
> the root cause is update_dimentions call get_pixel_format will
> trigger the hwaccel_uninit/hwaccel_init , in current context,
> there are 3 situations in the update_dimentions():
> 1. First time calling. No matter single thread or multithread,
>    get_pixel_format() should be called after dimentions were
>    set;
> 2. Dimention changed at the runtime. Dimention need to be
>    updated when macroblocks_base is already allocated,
>    get_pixel_format() should be called to recreate new frames
>    according to updated dimention;
> 3. Multithread first time calling. After decoder init, the
>    other threads will call update_dimentions() at first time
>    to allocate macroblocks_base and set dimentions.
>    But get_pixel_format() is shouldn't be called due to low
>    level frames and context are already created.
> In this fix, we only call update_dimentions as need.
>
> Signed-off-by: Wang, Shaofei <shaofei.wang at intel.com>
> Reviewed-by: Jun, Zhao <jun.zhao at intel.com>
> ---
>  libavcodec/vp8.c |    7 +++++--
>  1 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/libavcodec/vp8.c b/libavcodec/vp8.c
> index 3adfeac..18d1ada 100644
> --- a/libavcodec/vp8.c
> +++ b/libavcodec/vp8.c
> @@ -187,7 +187,7 @@ static av_always_inline
>  int update_dimensions(VP8Context *s, int width, int height, int is_vp7)
>  {
>      AVCodecContext *avctx = s->avctx;
> -    int i, ret;
> +    int i, ret, dim_reset = 0;
>
>      if (width  != s->avctx->width || ((width+15)/16 != s->mb_width ||
> (height+15)/16 != s->mb_height) && s->macroblocks_base ||
>          height != s->avctx->height) {
> @@ -196,9 +196,12 @@ int update_dimensions(VP8Context *s, int width, int
> height, int is_vp7)
>          ret = ff_set_dimensions(s->avctx, width, height);
>          if (ret < 0)
>              return ret;
> +
> +        dim_reset = (s->macroblocks_base != NULL);
>      }
>
> -    if (!s->actually_webp && !is_vp7) {
> +    if ((s->pix_fmt == AV_PIX_FMT_NONE || dim_reset) &&
> +         !s->actually_webp && !is_vp7) {

Why is the new variable dim_reset needed?
Wouldn't the patch be simpler if you used s->macroblocks_base
here?

Carl Eugen


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