[FFmpeg-devel] [PATCH 04/11] avcodec/mdec: allow/use permuted IDCTs

[Michael Niedermayer]

On Mon, Jun 19, 2017 at 05:10:57PM +0200, James Darnley wrote:
> From: "Ronald S. Bultje" <rsbultje at gmail.com>
> 
> ---
>  libavcodec/mdec.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/libavcodec/mdec.c b/libavcodec/mdec.c
> index 97bfebbeb7..1e1c8f4c55 100644
> --- a/libavcodec/mdec.c
> +++ b/libavcodec/mdec.c
> @@ -94,7 +94,7 @@ static inline int mdec_decode_block_intra(MDECContext *a, int16_t *block, int n)
>                      return AVERROR_INVALIDDATA;
>                  }
>                  j     = scantable[i];
> -                level = (level * qscale * quant_matrix[j]) >> 3;
> +                level = (level * qscale * quant_matrix[ff_zigzag_direct[i]]) >> 3;
>                  level = (level ^ SHOW_SBITS(re, &a->gb, 1)) - SHOW_SBITS(re, &a->gb, 1);
>                  LAST_SKIP_BITS(re, &a->gb, 1);
>              } else {
> @@ -111,11 +111,11 @@ static inline int mdec_decode_block_intra(MDECContext *a, int16_t *block, int n)
>                  j = scantable[i];
>                  if (level < 0) {
>                      level = -level;
> -                    level = (level * (unsigned)qscale * quant_matrix[j]) >> 3;
> +                    level = (level * (unsigned)qscale * quant_matrix[ff_zigzag_direct[i]]) >> 3;
>                      level = (level - 1) | 1;
>                      level = -level;
>                  } else {
> -                    level = (level * (unsigned)qscale * quant_matrix[j]) >> 3;
> +                    level = (level * (unsigned)qscale * quant_matrix[ff_zigzag_direct[i]]) >> 3;
>                      level = (level - 1) | 1;
>                  }
>              }

quant_matrix can be permuted during init to avoid the per coef
permutation here
Or it could be done per frame and also include the multiplication with
qscale

thx
[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Observe your enemies, for they first find out your faults. -- Antisthenes
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