txd: do not set the codec timebase.

It is not supposed to be changed from outside of lavc.
Set the stream timebase and average framerate instead.
lavc: improve AVCodecContext.delay doxy
avconv: always reset packet pts after decoding an audio frame

Currently, if a decoder sets AVFrame.pts, we'd send the same timestamp
to it twice, which is wrong.
lavf: do not use the parser duration for video

The parser has no way of knowing video duration, and therefore no video
parsers set it.
Merge commit 'a4ed995cabf220029f1d0e185a6fb45eed7b4091'

* commit 'a4ed995cabf220029f1d0e185a6fb45eed7b4091':
  txd: do not set the codec timebase.

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit 'b19a5e51981be5b69cf550a3bc17fe5300d0dbc9'

* commit 'b19a5e51981be5b69cf550a3bc17fe5300d0dbc9':
  lavc: improve AVCodecContext.delay doxy

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '1ae8198bca749a0cff205196cc83d35b9962849b'

* commit '1ae8198bca749a0cff205196cc83d35b9962849b':
  avconv: always reset packet pts after decoding an audio frame

Conflicts:
	ffmpeg.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit 'f9157463dbcd2db8fe9504197c0c04d0d7d04f31'

* commit 'f9157463dbcd2db8fe9504197c0c04d0d7d04f31':
  lavf: do not use the parser duration for video

Merged-by: Michael Niedermayer <michaelni@gmx.at>
vc1dsp: fix build without inline asm

Reviewed-by: Christophe Gisquet <christophe.gisquet@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>