On Sat, Oct 17, 2015 at 10:34:24PM +0200, Matthieu Bouron wrote:
> From: Matthieu Bouron <matthieu.bou...@stupeflix.com>
>
> Avoid decoding twice images such as jpeg and png, once in the
> avformat_find_stream_info and once when the actual decode is made.
>
> The decoder must honor the skip_frame option in order to skip
> decoding. For now the AVDISCARD_ALL flag is only set for the mjpeg and
> png decoders.
> ---
> libavformat/utils.c | 15 +++++++++++++++
> 1 file changed, 15 insertions(+)
>
> diff --git a/libavformat/utils.c b/libavformat/utils.c
> index 689473e..67dfffc 100644
> --- a/libavformat/utils.c
> +++ b/libavformat/utils.c
> @@ -2676,11 +2676,16 @@ static int has_codec_parameters(AVStream *st, const
> char **errmsg_ptr)
> static int try_decode_frame(AVFormatContext *s, AVStream *st, AVPacket
> *avpkt,
> AVDictionary **options)
> {
> + int i;
> const AVCodec *codec;
> int got_picture = 1, ret = 0;
> AVFrame *frame = av_frame_alloc();
> AVSubtitle subtitle;
> AVPacket pkt = *avpkt;
> + int skip_frame;
> + static const enum AVCodecID no_decode_codecs[] = {
> + AV_CODEC_ID_MJPEG, AV_CODEC_ID_PNG,
> + };
>
> if (!frame)
> return AVERROR(ENOMEM);
> @@ -2719,6 +2724,14 @@ static int try_decode_frame(AVFormatContext *s,
> AVStream *st, AVPacket *avpkt,
> goto fail;
> }
>
> + skip_frame = st->codec->skip_frame;
> + for (i = 0; i < FF_ARRAY_ELEMS(no_decode_codecs); i++) {
> + if (st->codec->codec_id == no_decode_codecs[i]) {
> + st->codec->skip_frame = AVDISCARD_ALL;
> + break;
> + }
> + }
> +
> while ((pkt.size > 0 || (!pkt.data && got_picture)) &&
> ret >= 0 &&
> (!has_codec_parameters(st, NULL) ||
> !has_decode_delay_been_guessed(st) ||
> @@ -2753,6 +2766,8 @@ static int try_decode_frame(AVFormatContext *s,
> AVStream *st, AVPacket *avpkt,
> if (!pkt.data && !got_picture)
> ret = -1;
>
> + st->codec->skip_frame = skip_frame;iam slightly unhappy about the possibility that someone could add a if(whatever) goto fail between these 2 and it would leave skip_frame in the modified state otherwise LGTM [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Those who are too smart to engage in politics are punished by being governed by those who are dumber. -- Plato
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