lavf/matroska*: add support for signed integers

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avformat/matroska: simplify signed int access code

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/vp9: fix "initialize" typo.

Originally spotted and fixed by one of these developers:
    Anton Khirnov <anton@khirnov.net>
    Diego Biurrun <diego@biurrun.de>
    Luca Barbato <lu_zero@gentoo.org>
    Martin Storsjö <martin@martin.st>

See 97962b2 / 72ca830
lavf/matroska*: DiscardPadding is a signed integer

according to the Matriska Specification
 http://matroska.org/technical/specs/index.html
DiscardPadding is a signed integer.

Tested-by: Jan Gerber <j@v2v.cc>
Tested-by: James Almer <jamrial@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
lavf/matroskadec ReferenceBlock is a signed integer

according to the Matroska Specification
ReferenceBlock is a signed integer too.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec: Fix duration error after seek operation

After seek, s->duration need recalculation, AVCodecParserContext need be set
again. Without the fix, the first audio packet would be dropped after
compute_pkt_fields() as the final pts/dts become invalid.

Signed-off-by: wangxingchao <wangxingchao@xiaomi.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avformat/rtmphttp: Partial fix for the ticket #3127 (second try)

Reviewed-by: Lukasz M <lukasz.m.luki@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
lavc: deprecate CODEC_CAP_NEG_LINESIZES

It was never used in any codec since it was added 3 years ago.
lavc: update coded_frame doxy.

It is not used during decoding anymore.
Replace all instances of avcodec_alloc_frame() with av_frame_alloc().
lavc: deprecate avcodec_alloc_frame().
a64multienc: use the AVFrame API properly.
asvenc: use the AVFrame API properly.
avs: use the AVFrame API properly.
bethsoftvid: use the AVFrame API properly.
c93: use the AVFrame API properly.
cdxl: remove an unused variable
cinepak: use the AVFrame API properly.
cljr: use the AVFrame API properly.
qtrle: use the AVFrame API properly.