[FFmpeg-devel] [PATCH 1/3] lavc/pngdec: honor skip_frame option

[Matthieu Bouron]

On Sat, Oct 17, 2015 at 10:34:22PM +0200, Matthieu Bouron wrote:
> From: Matthieu Bouron <matthieu.bouron at stupeflix.com>
> 
> ---
>  libavcodec/pngdec.c | 34 ++++++++++++++++++++++++++++++++++
>  1 file changed, 34 insertions(+)
> 
> diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c
> index 4cfdc58..5b2befe 100644
> --- a/libavcodec/pngdec.c
> +++ b/libavcodec/pngdec.c
> @@ -1087,6 +1087,13 @@ static int decode_frame_common(AVCodecContext *avctx, PNGDecContext *s,
>      for (;;) {
>          length = bytestream2_get_bytes_left(&s->gb);
>          if (length <= 0) {
> +
> +            if (avctx->codec_id == AV_CODEC_ID_PNG &&
> +                avctx->skip_frame == AVDISCARD_ALL) {
> +                av_frame_set_metadata(p, metadata);
> +                return 0;
> +            }
> +
>              if (CONFIG_APNG_DECODER && avctx->codec_id == AV_CODEC_ID_APNG && length == 0) {
>                  if (!(s->state & PNG_IDAT))
>                      return 0;
> @@ -1114,6 +1121,22 @@ static int decode_frame_common(AVCodecContext *avctx, PNGDecContext *s,
>                  ((tag >> 8) & 0xff),
>                  ((tag >> 16) & 0xff),
>                  ((tag >> 24) & 0xff), length);
> +
> +        if (avctx->codec_id == AV_CODEC_ID_PNG &&
> +            avctx->skip_frame == AVDISCARD_ALL) {
> +            int i, found = 0;
> +            static const int tags[] = { MKTAG('I', 'H', 'D', 'R'), MKTAG('t', 'E', 'X', 't'), MKTAG('I', 'D', 'A', 'T') };
> +            for (i = 0; i < FF_ARRAY_ELEMS(tags); i++) {
> +                if (tag == tags[i]) {
> +                    found = 1;
> +                    break;
> +                }
> +            }
> +            if (!found) {
> +                goto skip_tag;
> +            }
> +        }
> +
>          switch (tag) {
>          case MKTAG('I', 'H', 'D', 'R'):
>              if ((ret = decode_ihdr_chunk(avctx, s, length)) < 0)
> @@ -1181,6 +1204,11 @@ skip_tag:
>          }
>      }
>  exit_loop:
> +    if (avctx->codec_id == AV_CODEC_ID_PNG &&
> +        avctx->skip_frame == AVDISCARD_ALL) {
> +        av_frame_set_metadata(p, metadata);
> +        return 0;
> +    }
>  
>      if (s->bits_per_pixel <= 4)
>          handle_small_bpp(s, p);
> @@ -1278,6 +1306,12 @@ static int decode_frame_png(AVCodecContext *avctx,
>      if ((ret = decode_frame_common(avctx, s, p, avpkt)) < 0)
>          goto the_end;
>  
> +    if (avctx->skip_frame == AVDISCARD_ALL) {
> +        *got_frame = 0;
> +        ret = bytestream2_tell(&s->gb);
> +        goto the_end;
> +    }
> +
>      if ((ret = av_frame_ref(data, s->picture.f)) < 0)
>          return ret;
>  
> -- 
> 2.6.1
> 

Patch updated, the SAR is not discarded anymore.

Matthieu
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