[FFmpeg-devel] [PATCH 2/2] avcodec/huffyuvdec: optimize decode_plane_bitstream(), use joint tables for new yuv formats

[Paul B Mahol]

On 1/1/14, Michael Niedermayer <michaelni at gmx.at> wrote:
> Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
> ---
>  libavcodec/huffyuvdec.c |   23 ++++++++++++++++-------
>  1 file changed, 16 insertions(+), 7 deletions(-)
>
> diff --git a/libavcodec/huffyuvdec.c b/libavcodec/huffyuvdec.c
> index 11c87bd..b88e683 100644
> --- a/libavcodec/huffyuvdec.c
> +++ b/libavcodec/huffyuvdec.c
> @@ -114,11 +114,12 @@ static int generate_joint_tables(HYuvContext *s)
>      uint8_t len[1 << VLC_BITS];
>      int ret;
>
> -    if (s->bitstream_bpp < 24) {
> +    if (s->bitstream_bpp < 24 || s->version > 2) {
>          int p, i, y, u;
>          for (p = 0; p < 3; p++) {
> +            int p0 = s->version > 2 ? p : 0;
>              for (i = y = 0; y < 256; y++) {
> -                int len0 = s->len[0][y];
> +                int len0 = s->len[p0][y];
>                  int limit = VLC_BITS - len0;
>                  if(limit <= 0 || !len0)
>                      continue;
> @@ -128,7 +129,7 @@ static int generate_joint_tables(HYuvContext *s)
>                          continue;
>                      av_assert0(i < (1 << VLC_BITS));
>                      len[i] = len0 + len1;
> -                    bits[i] = (s->bits[0][y] << len1) + s->bits[p][u];
> +                    bits[i] = (s->bits[p0][y] << len1) + s->bits[p][u];
>                      symbols[i] = (y << 8) + u;
>                      if(symbols[i] != 0xffff) // reserved to mean "invalid"
>                          i++;
> @@ -461,6 +462,16 @@ static void decode_422_bitstream(HYuvContext *s, int
> count)
>      }
>  }
>
> +#define READ_2PIX_PLANE(dst0, dst1, plane){\
> +    uint16_t code = get_vlc2(&s->gb, s->vlc[3+plane].table, VLC_BITS, 1);\
> +    if(code != 0xffff){\
> +        dst0 = code>>8;\
> +        dst1 = code;\
> +    }else{\
> +        dst0 = get_vlc2(&s->gb, s->vlc[plane].table, VLC_BITS, 3);\
> +        dst1 = get_vlc2(&s->gb, s->vlc[plane].table, VLC_BITS, 3);\
> +    }\
> +}
>  static void decode_plane_bitstream(HYuvContext *s, int count, int plane)
>  {
>      int i;
> @@ -469,13 +480,11 @@ static void decode_plane_bitstream(HYuvContext *s, int
> count, int plane)
>
>      if (count >= (get_bits_left(&s->gb)) / (31 * 2)) {
>          for (i = 0; i < count && get_bits_left(&s->gb) > 0; i++) {
> -            s->temp[0][2*i    ] = get_vlc2(&s->gb, s->vlc[plane].table,
> VLC_BITS, 3);
> -            s->temp[0][2*i + 1] = get_vlc2(&s->gb, s->vlc[plane].table,
> VLC_BITS, 3);
> +            READ_2PIX_PLANE(s->temp[0][2 * i], s->temp[0][2 * i + 1],
> plane);
>          }
>      } else {
>          for(i=0; i<count; i++){
> -            s->temp[0][2*i    ] = get_vlc2(&s->gb, s->vlc[plane].table,
> VLC_BITS, 3);
> -            s->temp[0][2*i + 1] = get_vlc2(&s->gb, s->vlc[plane].table,
> VLC_BITS, 3);
> +            READ_2PIX_PLANE(s->temp[0][2 * i], s->temp[0][2 * i + 1],
> plane);
>          }
>      }
>  }
> --
> 1.7.9.5
>
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>

probably ok