[FFmpeg-devel] [PATCH 4/7] avcodec/dvbsubdec: Support computing clut only once

[Marton Balint]

On Thu, 4 Mar 2021, Michael Niedermayer wrote:

> This avoids crafted files from consuming excessive resources recomputing the clut after each pixel change
>
> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> ---
> libavcodec/dvbsubdec.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)

PLease update doc/decoders.texi as well.

Thanks,
Marton

>
> diff --git a/libavcodec/dvbsubdec.c b/libavcodec/dvbsubdec.c
> index 9bee33e4a2..6f340460d8 100644
> --- a/libavcodec/dvbsubdec.c
> +++ b/libavcodec/dvbsubdec.c
> @@ -979,7 +979,8 @@ static void dvbsub_parse_pixel_data_block(AVCodecContext *avctx, DVBSubObjectDis
>         }
>     }
> 
> -    region->has_computed_clut = 0;
> +    if (ctx->compute_clut != -2)
> +        region->has_computed_clut = 0;
> }
> 
> static int dvbsub_parse_object_segment(AVCodecContext *avctx,
> @@ -1737,7 +1738,7 @@ end:
> #define OFFSET(x) offsetof(DVBSubContext, x)
> static const AVOption options[] = {
>     {"compute_edt", "compute end of time using pts or timeout", OFFSET(compute_edt), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, DS},
> -    {"compute_clut", "compute clut when not available(-1) or always(1) or never(0)", OFFSET(compute_clut), AV_OPT_TYPE_BOOL, {.i64 = -1}, -1, 1, DS},
> +    {"compute_clut", "compute clut when not available(-1) or only once (-2) or always(1) or never(0)", OFFSET(compute_clut), AV_OPT_TYPE_BOOL, {.i64 = -1}, -2, 1, DS},
>     {"dvb_substream", "", OFFSET(substream), AV_OPT_TYPE_INT, {.i64 = -1}, -1, 63, DS},
>     {NULL}
> };
> -- 
> 2.17.1
>
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