[FFmpeg-devel] [PATCH] lavc/mjpegdec: fix VA-API MJPEG decoding uninitialized huffman table

Li, Zhong zhong.li at intel.com
Tue Oct 30 04:41:13 EET 2018


> From: ffmpeg-devel [mailto:ffmpeg-devel-bounces at ffmpeg.org] On Behalf
> Of mypopy at gmail.com
> Sent: Tuesday, October 30, 2018 9:02 AM
> To: FFmpeg development discussions and patches
> <ffmpeg-devel at ffmpeg.org>
> Cc: Zhao, Jun <jun.zhao at intel.com>; Lin, Decai <decai.lin at intel.com>
> Subject: Re: [FFmpeg-devel] [PATCH] lavc/mjpegdec: fix VA-API MJPEG
> decoding uninitialized huffman table
> 
> On Mon, Oct 29, 2018 at 6:39 PM Li, Zhong <zhong.li at intel.com> wrote:
> >
> > > From: ffmpeg-devel [mailto:ffmpeg-devel-bounces at ffmpeg.org] On
> > > Behalf Of Jun Zhao
> > > Sent: Monday, October 29, 2018 6:26 PM
> > > To: ffmpeg-devel at ffmpeg.org
> > > Cc: Zhao, Jun <jun.zhao at intel.com>; Lin, Decai <decai.lin at intel.com>
> > > Subject: [FFmpeg-devel] [PATCH] lavc/mjpegdec: fix VA-API MJPEG
> > > decoding uninitialized huffman table
> > >
> > > From: Jun Zhao <jun.zhao at intel.com>
> > >
> > > Now VA-API HWAccel MJPEG decoding uninitialized huffman table, it's
> > > will lead to the decoding error like"Failed to sync surface 0x5: 23
> > > (internal decoding error)." in iHD open source driver.
> > >
> > > Signed-off-by: dlin2 <decai.lin at intel.com>
> > > Signed-off-by: Jun Zhao <jun.zhao at intel.com>
> > > ---
> > >  libavcodec/mjpegdec.c |   19 +++++++++++++++++++
> > >  1 files changed, 19 insertions(+), 0 deletions(-)
> > >
> > > diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c index
> > > b0cb3ff..89effb6 100644
> > > --- a/libavcodec/mjpegdec.c
> > > +++ b/libavcodec/mjpegdec.c
> > > @@ -75,6 +75,25 @@ static int build_vlc(VLC *vlc, const uint8_t
> > > *bits_table, static int build_basic_mjpeg_vlc(MJpegDecodeContext *s)
> {
> > >      int ret;
> > > +    int i;
> > > +
> > > +    /* initialize default huffman tables */
> > > +    for (i = 0; i < 16; i++)
> > > +        s->raw_huffman_lengths[0][0][i] =
> > > avpriv_mjpeg_bits_dc_luminance[i + 1];
> > > +    for (i = 0; i < 12; i++)
> > > +        s->raw_huffman_values[0][0][i] = avpriv_mjpeg_val_dc[i];
> > > +    for (i = 0; i < 16; i++)
> > > +        s->raw_huffman_lengths[0][1][i] =
> > > avpriv_mjpeg_bits_dc_chrominance[i + 1];
> > > +    for (i = 0; i < 12; i++)
> > > +        s->raw_huffman_values[0][1][i] = avpriv_mjpeg_val_dc[i];
> > > +    for (i = 0; i < 16; i++)
> > > +        s->raw_huffman_lengths[1][0][i] =
> > > avpriv_mjpeg_bits_ac_luminance[i + 1];
> > > +    for (i = 0; i < 162; i++)
> > > +        s->raw_huffman_values[1][0][i] =
> > > avpriv_mjpeg_val_ac_luminance[i];
> > > +    for (i = 0; i < 16; i++)
> > > +        s->raw_huffman_lengths[1][1][i] =
> > > avpriv_mjpeg_bits_ac_chrominance[i + 1];
> > > +    for (i = 0; i < 162; i++)
> > > +        s->raw_huffman_values[1][1][i] =
> > > + avpriv_mjpeg_val_ac_chrominance[i];
> > >
> > >      if ((ret = build_vlc(&s->vlcs[0][0],
> avpriv_mjpeg_bits_dc_luminance,
> > >                           avpriv_mjpeg_val_dc, 12, 0, 0)) < 0)
> > > --
> > > 1.7.1
> >
> > Should this be fixed in iHD driver instead of ffmpeg?
> No, I don't think driver is a good place to initialize the huffman table.

For the default Huffman table, thus should be initialized by driver itself. 
For non-default case, thus should be passed from ffmpeg.
So, what is the case you want to fix? Both (if so, no need to mention iHD driver)? 



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