[Mesa-dev] [PATCH v2] vl/rbsp: add a check for emulation prevention three byte

[Christian König]

Am 09.08.2016 um 17:18 schrieb Leo Liu:
> This is the case when the "00 00 03" is very close to the beginning of
> nal unit header
>
> v2: move the check to rbsp init
>
> Signed-off-by: Leo Liu <leo.liu at amd.com>

Reviewed-by: Christian König <christian.koenig at amd.com>

> ---
>   src/gallium/auxiliary/vl/vl_rbsp.h | 14 ++++++++++++--
>   1 file changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/src/gallium/auxiliary/vl/vl_rbsp.h b/src/gallium/auxiliary/vl/vl_rbsp.h
> index 7867238..c8bebff 100644
> --- a/src/gallium/auxiliary/vl/vl_rbsp.h
> +++ b/src/gallium/auxiliary/vl/vl_rbsp.h
> @@ -50,7 +50,8 @@ struct vl_rbsp {
>    */
>   static inline void vl_rbsp_init(struct vl_rbsp *rbsp, struct vl_vlc *nal, unsigned num_bits)
>   {
> -   unsigned bits_left = vl_vlc_bits_left(nal);
> +   unsigned valid, bits_left = vl_vlc_bits_left(nal);
> +   int i;
>   
>      /* copy the position */
>      rbsp->nal = *nal;
> @@ -62,10 +63,19 @@ static inline void vl_rbsp_init(struct vl_rbsp *rbsp, struct vl_vlc *nal, unsign
>         if (vl_vlc_peekbits(nal, 24) == 0x000001 ||
>             vl_vlc_peekbits(nal, 32) == 0x00000001) {
>            vl_vlc_limit(&rbsp->nal, bits_left - vl_vlc_bits_left(nal));
> -         return;
> +         break;
>         }
>         vl_vlc_eatbits(nal, 8);
>      }
> +
> +   valid = vl_vlc_valid_bits(&rbsp->nal);
> +   /* search for the emulation prevention three byte */
> +   for (i = 24; i <= valid; i += 8) {
> +      if ((vl_vlc_peekbits(&rbsp->nal, i) & 0xffffff) == 0x3) {
> +         vl_vlc_removebits(&rbsp->nal, i - 8, 8);
> +         i += 8;
> +      }
> +   }
>   }
>   
>   /**