Re: [FFmpeg-devel] [PATCH 2/4] lavc/mpegvideo: use H263DSP dequant function

[Michael Niedermayer <michael@niedermayer.cc>]

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On Sun, Jun 09, 2024 at 07:23:45PM +0300, Rémi Denis-Courmont wrote:
> ---
>  libavcodec/mpegvideo.c | 44 ++++++++++--------------------------------
>  1 file changed, 10 insertions(+), 34 deletions(-)
> 
> diff --git a/libavcodec/mpegvideo.c b/libavcodec/mpegvideo.c
> index 7af823b8bd..9be0fecc8d 100644
> --- a/libavcodec/mpegvideo.c
> +++ b/libavcodec/mpegvideo.c
> @@ -201,13 +201,11 @@ static void dct_unquantize_mpeg2_inter_c(MpegEncContext *s,
>  static void dct_unquantize_h263_intra_c(MpegEncContext *s,
>                                    int16_t *block, int n, int qscale)
>  {
> -    int i, level, qmul, qadd;
> -    int nCoeffs;
> +    int qmul = qscale << 1;
> +    int qadd, nCoeffs;
>  
>      av_assert2(s->block_last_index[n]>=0 || s->h263_aic);
>  
> -    qmul = qscale << 1;
> -
>      if (!s->h263_aic) {
>          block[0] *= n < 4 ? s->y_dc_scale : s->c_dc_scale;
>          qadd = (qscale - 1) | 1;
> @@ -215,47 +213,24 @@ static void dct_unquantize_h263_intra_c(MpegEncContext *s,
>          qadd = 0;
>      }
>      if(s->ac_pred)
> -        nCoeffs=63;
> +        nCoeffs = 64;
>      else
> -        nCoeffs= s->intra_scantable.raster_end[ s->block_last_index[n] ];
> +        nCoeffs = s->intra_scantable.raster_end[s->block_last_index[n]] + 1;
>  
> -    for(i=1; i<=nCoeffs; i++) {
> -        level = block[i];
> -        if (level) {
> -            if (level < 0) {
> -                level = level * qmul - qadd;
> -            } else {
> -                level = level * qmul + qadd;
> -            }
> -            block[i] = level;
> -        }
> -    }
> +    s->h263dsp.h263_dct_unquantize_intra(block, nCoeffs, qmul, qadd);
>  }
>  
>  static void dct_unquantize_h263_inter_c(MpegEncContext *s,
>                                    int16_t *block, int n, int qscale)
>  {
> -    int i, level, qmul, qadd;
> +    int qmul = qscale << 1;
> +    int qadd = (qscale - 1) | 1;
>      int nCoeffs;
>  
>      av_assert2(s->block_last_index[n]>=0);
>  
> -    qadd = (qscale - 1) | 1;
> -    qmul = qscale << 1;
> -
> -    nCoeffs= s->inter_scantable.raster_end[ s->block_last_index[n] ];
> -
> -    for(i=0; i<=nCoeffs; i++) {
> -        level = block[i];
> -        if (level) {
> -            if (level < 0) {
> -                level = level * qmul - qadd;
> -            } else {
> -                level = level * qmul + qadd;
> -            }
> -            block[i] = level;
> -        }
> -    }
> +    nCoeffs = s->inter_scantable.raster_end[s->block_last_index[n]] + 1;
> +    s->h263dsp.h263_dct_unquantize_inter(block, nCoeffs, qmul, qadd);

It would be better if the "+ 1" would not be needed and teh functions
would keep using "<="

thx

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

During times of universal deceit, telling the truth becomes a
revolutionary act. -- George Orwell

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