[FFmpeg-devel] [PATCH] avcodec/h263dec: Avoid copying data when flipping image

[Andreas Rheinhardt]

Andreas Rheinhardt:
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>
> ---
>  libavcodec/h263dec.c | 14 ++++----------
>  1 file changed, 4 insertions(+), 10 deletions(-)
> 
> diff --git a/libavcodec/h263dec.c b/libavcodec/h263dec.c
> index e940b7f7c7..423036e97b 100644
> --- a/libavcodec/h263dec.c
> +++ b/libavcodec/h263dec.c
> @@ -703,17 +703,11 @@ frame_end:
>      if (s->last_picture_ptr || s->low_delay) {
>          if (   pict->format == AV_PIX_FMT_YUV420P
>              && (s->codec_tag == AV_RL32("GEOV") || s->codec_tag == AV_RL32("GEOX"))) {
> -            int x, y, p;
> -            av_frame_make_writable(pict);
> -            for (p=0; p<3; p++) {
> -                int w = AV_CEIL_RSHIFT(pict-> width, !!p);
> +            for (int p = 0; p < 3; p++) {
>                  int h = AV_CEIL_RSHIFT(pict->height, !!p);
> -                int linesize = pict->linesize[p];
> -                for (y=0; y<(h>>1); y++)
> -                    for (x=0; x<w; x++)
> -                        FFSWAP(int,
> -                               pict->data[p][x + y*linesize],
> -                               pict->data[p][x + (h-1-y)*linesize]);
> +
> +                pict->data[p]     += (h - 1) * pict->linesize[p];
> +                pict->linesize[p] *= -1;
>              }
>          }
>          *got_frame = 1;

Will apply this tomorrow unless there are objections.

- Andreas