[FFmpeg-devel] [PATCH] oggdec: validate VP8 keyframes

[Michael Niedermayer]

On Thu, Jan 09, 2014 at 10:54:04PM -0300, James Almer wrote:
> On 09/01/14 10:37 PM, Ronald S. Bultje wrote:
> > Hi,
> > 
> > On Thu, Jan 9, 2014 at 5:16 PM, James Almer <jamrial at gmail.com> wrote:
> > 
> >> Fixes seeking in files with broken files
> >>
> >> Signed-off-by: James Almer <jamrial at gmail.com>
> >> ---
> >>  libavformat/oggdec.c | 12 ++++++++++--
> >>  1 file changed, 10 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/libavformat/oggdec.c b/libavformat/oggdec.c
> >> index efb8f04..9200432 100644
> >> --- a/libavformat/oggdec.c
> >> +++ b/libavformat/oggdec.c
> >> @@ -722,8 +722,16 @@ static void ogg_validate_keyframe(AVFormatContext *s,
> >> int idx, int pstart, int p
> >>  {
> >>      struct ogg *ogg = s->priv_data;
> >>      struct ogg_stream *os = ogg->streams + idx;
> >> -    if (psize && s->streams[idx]->codec->codec_id == AV_CODEC_ID_THEORA) {
> >> -        if (!!(os->pflags & AV_PKT_FLAG_KEY) != !(os->buf[pstart] &
> >> 0x40)) {
> >> +    int invalid = 0;
> >> +    if (psize) {
> >> +        switch (s->streams[idx]->codec->codec_id) {
> >> +        case AV_CODEC_ID_THEORA:
> >> +            invalid = !!(os->pflags & AV_PKT_FLAG_KEY) !=
> >> !(os->buf[pstart] & 0x40);
> >> +        break;
> >> +        case AV_CODEC_ID_VP8:
> >> +            invalid = !!(os->pflags & AV_PKT_FLAG_KEY) !=
> >> !(os->buf[pstart] & 1);
> >> +        }
> >> +        if (invalid) {
> >>              os->pflags ^= AV_PKT_FLAG_KEY;
> >>              av_log(s, AV_LOG_WARNING, "Broken file, %skeyframe not
> >> correctly marked.\n",
> >>                     (os->pflags & AV_PKT_FLAG_KEY) ? "" : "non-");
> >>
> > 
> > Isn't this duplicate with vp8_parser.c, or in other words, shouldn't we
> > invoke the AVParser if it exists?
> > 
> > Ronald
> 
> I thought the vp8 parser was being invoked by setting st->need_parsing? oggparsevp8 
> is doing that currently.
> Nonetheless, the vp8 parser marks I and P frames, but it doesn't seem to set the 
> AV_PKT_FLAG_KEY flag for the packet (That's done by the demuxer).
> 
> I did the same thing we're doing for Theora here, fixing wrongly marked keyframes 
> before sending them to the decoder. It fixed seeking with such broken files for me.

parse_packet() sets the AVPacket keyframe flags from the parser

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-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I have never wished to cater to the crowd; for what I know they do not
approve, and what they approve I do not know. -- Epicurus
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