| Message ID | 20190809162959.17924-5-velocityra@gmail.com |
|---|---|
| State | Superseded |
| Headers | show |
On Fri, Aug 09, 2019 at 07:29:50PM +0300, Nick Renieris wrote: > From: Nick Renieris <velocityra@gmail.com> > > Some JPEGs [1] have incorrect DHT entries that map 2 codes to > the same value. > > The second (last) mapping does not ever actually appear in the > code stream, therefore ignoring any mappings after the first one > fixes this. > > Without this, an "mjpeg_decode_dc: bad vlc: 0:0" error is thrown. > > --- > > [1]: Embedded JPEGs in "X7 RAW" and "X7 CinemaDNG" samples here: > https://www.dji.com/gr/zenmuse-x7/info#downloads > > Signed-off-by: Nick Renieris <velocityra@gmail.com> > --- > libavcodec/jpegtables.c | 19 ++++++++++++++++--- > 1 file changed, 16 insertions(+), 3 deletions(-) > > diff --git a/libavcodec/jpegtables.c b/libavcodec/jpegtables.c > index cbe5523cb4..6f596cfc92 100644 > --- a/libavcodec/jpegtables.c > +++ b/libavcodec/jpegtables.c > @@ -130,14 +130,27 @@ void ff_mjpeg_build_huffman_codes(uint8_t *huff_size, uint16_t *huff_code, > { > int i, j, k,nb, code, sym; > > - code = 0; > + /* Zero-initialize huff_size (needed for multiple mappings check below) */ > + k = 0; > + for(i=1;i<=16;i++) { > + nb = bits_table[i]; > + for(j=0;j<nb;j++) { > + sym = val_table[k++]; > + huff_size[sym] = 0; > + } > + } > + > k = 0; > + code = 0; > for(i=1;i<=16;i++) { > nb = bits_table[i]; > for(j=0;j<nb;j++) { > sym = val_table[k++]; > - huff_size[sym] = i; > - huff_code[sym] = code; > + /* If there are multiple mappings to the same sym (bad files), keep the first code */ > + if (huff_size[sym] == 0) { > + huff_size[sym] = i; > + huff_code[sym] = code; > + } do these occur with sym different from 0 ? if its just 0 then this can be simplified alot [...]
I haven't seen any files with sym!=0, just thought I'd solve the general case. I'll change only for sym==0. Can always be changed later if any such samples are found. Στις Σάβ, 10 Αυγ 2019 στις 4:11 μ.μ., ο/η Michael Niedermayer <michael@niedermayer.cc> έγραψε: > > On Fri, Aug 09, 2019 at 07:29:50PM +0300, Nick Renieris wrote: > > From: Nick Renieris <velocityra@gmail.com> > > > > Some JPEGs [1] have incorrect DHT entries that map 2 codes to > > the same value. > > > > The second (last) mapping does not ever actually appear in the > > code stream, therefore ignoring any mappings after the first one > > fixes this. > > > > Without this, an "mjpeg_decode_dc: bad vlc: 0:0" error is thrown. > > > > --- > > > > [1]: Embedded JPEGs in "X7 RAW" and "X7 CinemaDNG" samples here: > > https://www.dji.com/gr/zenmuse-x7/info#downloads > > > > Signed-off-by: Nick Renieris <velocityra@gmail.com> > > --- > > libavcodec/jpegtables.c | 19 ++++++++++++++++--- > > 1 file changed, 16 insertions(+), 3 deletions(-) > > > > diff --git a/libavcodec/jpegtables.c b/libavcodec/jpegtables.c > > index cbe5523cb4..6f596cfc92 100644 > > --- a/libavcodec/jpegtables.c > > +++ b/libavcodec/jpegtables.c > > @@ -130,14 +130,27 @@ void ff_mjpeg_build_huffman_codes(uint8_t *huff_size, uint16_t *huff_code, > > { > > int i, j, k,nb, code, sym; > > > > - code = 0; > > + /* Zero-initialize huff_size (needed for multiple mappings check below) */ > > + k = 0; > > + for(i=1;i<=16;i++) { > > + nb = bits_table[i]; > > + for(j=0;j<nb;j++) { > > + sym = val_table[k++]; > > + huff_size[sym] = 0; > > + } > > + } > > + > > k = 0; > > + code = 0; > > for(i=1;i<=16;i++) { > > nb = bits_table[i]; > > for(j=0;j<nb;j++) { > > sym = val_table[k++]; > > - huff_size[sym] = i; > > - huff_code[sym] = code; > > + /* If there are multiple mappings to the same sym (bad files), keep the first code */ > > + if (huff_size[sym] == 0) { > > + huff_size[sym] = i; > > + huff_code[sym] = code; > > + } > > do these occur with sym different from 0 ? > if its just 0 then this can be simplified alot > > [...] > -- > Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB > > I do not agree with what you have to say, but I'll defend to the death your > right to say it. -- Voltaire > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > To unsubscribe, visit link above, or email > ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".
diff --git a/libavcodec/jpegtables.c b/libavcodec/jpegtables.c index cbe5523cb4..6f596cfc92 100644 --- a/libavcodec/jpegtables.c +++ b/libavcodec/jpegtables.c @@ -130,14 +130,27 @@ void ff_mjpeg_build_huffman_codes(uint8_t *huff_size, uint16_t *huff_code, { int i, j, k,nb, code, sym; - code = 0; + /* Zero-initialize huff_size (needed for multiple mappings check below) */ + k = 0; + for(i=1;i<=16;i++) { + nb = bits_table[i]; + for(j=0;j<nb;j++) { + sym = val_table[k++]; + huff_size[sym] = 0; + } + } + k = 0; + code = 0; for(i=1;i<=16;i++) { nb = bits_table[i]; for(j=0;j<nb;j++) { sym = val_table[k++]; - huff_size[sym] = i; - huff_code[sym] = code; + /* If there are multiple mappings to the same sym (bad files), keep the first code */ + if (huff_size[sym] == 0) { + huff_size[sym] = i; + huff_code[sym] = code; + } code++; } code <<= 1;