pcm-dvd: Support channel configuration changes

The sample buffering logic does not take into account that the blocksize
could change. Reset the buffer if the channel configuration changes,
since if there are leftover samples, it is most likely a broken or
misconcatenated stream. This could lead to negative numbers for
missing_samples during decoding.

Thanks to Michael Niedermeyer for pointing these out.
pcm-dvd: Minor leftovers

Drop a pointless branch in uninit and use the compact copyright.
mem: Document the non-compatibility of av_realloc() and av_malloc()
mathops/x86: work around inline asm miscompilation with GCC 4.8.1

The volatile is not required here, and prevents a miscompilation with GCC
4.8.1 when building on x86 with --cpu=i686

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>
omadec: Properly check lengths before incrementing the position

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
Signed-off-by: Martin Storsjö <martin@martin.st>
sierravmd: Do sanity checking of frame sizes

Limit the size to INT_MAX/2 (for simplicity) to be sure that
size + BYTES_PER_FRAME_RECORD won't overflow.

Also factorize other existing error return paths.

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
Signed-off-by: Martin Storsjö <martin@martin.st>
vocdec: Don't update codec parameters mid-stream

If we really want to support parameter changes, they need to be
signalled along with the AVPackets as parameter change side data,
not just changing the AVCodecContext parameters when a packet
is demuxed (since there may be other earlier packets yet undecoded).

Something similar was already done for the sample rate in 0883109b2,
but some parameters were left changeable.

This avoids having to recheck the channel count for validity for
each decoded frame in (ad)pcm decoders, unless the decoders
explicitly say that they accept parameter changes.

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
Signed-off-by: Martin Storsjö <martin@martin.st>
cavsdec: Make sure a sequence header has been decoded before decoding pictures

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
Signed-off-by: Martin Storsjö <martin@martin.st>
proresdec: Properly make sure an index doesn't run past the limit

If idx equaled num_coeffs - 1 on entry to the loop, the previous
check failed to break out of the loop.

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
Signed-off-by: Martin Storsjö <martin@martin.st>
vp3: Check the framerate for validity

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
Signed-off-by: Martin Storsjö <martin@martin.st>
avpacket: Fix error checking in packet_alloc

Previously the wrong buffer pointer was checked, when buf
instead of *buf was checked. But checking the return value
instead is even better.

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
Signed-off-by: Martin Storsjö <martin@martin.st>
Fix references to deleted avcodec_encode_video() function
lavc: add ff_u8_to_s8() for safe type punning of uint8_t to int8_t
Add a WebP decoder

Container and lossy decoding by Aneesh Dogra <aneesh@sugarlabs.org>
Lossless decoding by Justin Ruggles <justin.ruggles@gmail.com>