According to the WebP Lossless Bitstream Specification
"each transform is allowed to be used only once".
If a transform is more than once this can lead to memory
corruption.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
According to the WebP Lossless Bitstream Specification the highest
allowed value for a prefix code is 39.
If prefix_code is too large, the calculated extra_bits has an invalid
value and triggers an assertion in get_bits.
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
it should not be possible to be larger as its stored as 8bit value
but we would be overwriting a stack buffer if it is ...
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
See https://code.google.com/p/webp/issues/detail?id=206
for a description of the problem/fix.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This patch makes the decoder follow the recommendation of the spec.
There is some disagreement (see "[FFmpeg-devel] [PATCH]: libavcodec/webp")
about what would be best to be written in the spec, so in case the spec
is changed again, this potentially would need to be amended or reverted
* commit 'c6698dfe7cdbc7634f33245875488ed3fa4a8ced':
webpdec: Fix decoding of the huffman group indices.
Merged-by: Michael Niedermayer <michaelni@gmx.at>
Also remove "webp:" from log messages. Using the AVCodecContext is enough.
Signed-off-by: James Almer <jamrial@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
* commit 'f51e3a1971045c7ed0c3d9d29d3254a4d940198e':
webp: do not call av_frame_free() on the user-provided frame
Merged-by: Michael Niedermayer <michaelni@gmx.at>
The vlc reader cannot handle 0-bit huffman codes. For most
situations WebP uses the "simple" huffman coding for this case,
but that will only handle symbols up to 255. For the LZ77 distance
codes, larger symbol values are needed, so it can happen in rare
cases that a normal huffman table is used that only has a single
symbol.
* commit 'c4bfa098072ba338d83555d6e2199f7e1e64ffff':
Add a WebP decoder
Conflicts:
Changelog
doc/general.texi
libavcodec/Makefile
libavcodec/avcodec.h
libavcodec/version.h
libavformat/img2.c
The previously existing webp decoder is disabled as the new
one supports lossless mode and alpha while the previous does not.
Merged-by: Michael Niedermayer <michaelni@gmx.at>
