[FFmpeg-devel] [PATCH v12 12/14] lavc/mjpegdec: Skip useless APPx marker on bayer images

[Nick Renieris]

The data the marker contains is only 2 bytes and they're 0x0000 in the
samples above. I don't know what they're for.


Στις Σάβ, 10 Αυγ 2019 στις 3:16 μ.μ., ο/η Michael Niedermayer
<michael at niedermayer.cc> έγραψε:
>
> On Fri, Aug 09, 2019 at 07:29:57PM +0300, Nick Renieris wrote:
> > From: Nick Renieris <velocityra at gmail.com>
> >
> > Samples:
> > - Embedded JPEG images in the DNG images here:
> >   https://www.photographyblog.com/previews/pentax_k1_photos
> >
> > Signed-off-by: Nick Renieris <velocityra at gmail.com>
> > ---
> >  libavcodec/mjpegdec.c | 11 +++++++++--
> >  1 file changed, 9 insertions(+), 2 deletions(-)
> >
> > diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c
> > index 0a920a7144..e7b273a363 100644
> > --- a/libavcodec/mjpegdec.c
> > +++ b/libavcodec/mjpegdec.c
> > @@ -1807,8 +1807,15 @@ static int mjpeg_decode_app(MJpegDecodeContext *s)
> >      int len, id, i;
> >
> >      len = get_bits(&s->gb, 16);
> > -    if (len < 6)
> > -        return AVERROR_INVALIDDATA;
> > +    if (len < 6) {
> > +        if (s->bayer) {
> > +            // Pentax K-1 (digital camera) JPEG images embedded in DNG images contain useless APP0 markers
>
> "useless" is a quite generic term, is it known what the contain why they
> are there ?
>
> thx
>
> [...]
> --
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> Asymptotically faster algorithms should always be preferred if you have
> asymptotical amounts of data
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