doc: filters: Correct BNF FILTER description

Signed-off-by: Diego Biurrun <diego@biurrun.de>
(cherry picked from commit b5ad422bf4e671a8b30ce73ad236cd6b49940af9)
doc: developer: Allow tabs in the vim configuration for Automake files

While we do not use Automake in libav, this allows our config to be
used more globally without introducing unwanted breakage.
(cherry picked from commit 040c565e51985477a8fa5e42d2ddfb26ebde6608)

Conflicts:

	doc/developer.texi
ac3dec: validate channel output mode against channel count

Damaged frames can lead to a mismatch, which can cause a segfault
due to using an incorrect channel mapping.

CC:libav-stable@libav.org
(cherry picked from commit d7c450436fcb9d3ecf59884a574e7684183e753d)

Conflicts:

	libavcodec/ac3dec.c
vorbisdec: Add missing checks

Rate and order must not be 0 even if the specification does not say that
explicitly.
(cherry picked from commit 5b47c19bfda92273ae49e83db26a565afcaed80a)

Signed-off-by: Reinhard Tartler <siretart@tauware.de>
vorbisdec: Error on bark_map_size equal to 0.

The value is used to calculate output LSP curve and a division by zero
and out of array accesses would occur.

CVE-2013-0894

CC: libav-stable@libav.org

Reported-by: Dale Curtis <dalecurtis@chromium.org>
Found-by: inferno@chromium.org
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
(cherry picked from commit 11dcecfcca0eca1a571792c4fa3c21fb2cfddddc)

Signed-off-by: Reinhard Tartler <siretart@tauware.de>
vorbisdec: Accept 0 amplitude_bits

The specification does not prevent an encoder to write the amplitude 0
as 0 amplitude_bits.

Our get_bits() implementation might not support a zero sized read
properly, thus the additional branch.
(cherry picked from commit 23bd9ef4b209c789d5473d75f89a2e411d343d80)

Conflicts:

	libavcodec/vorbisdec.c