Currently, AVStream contains an embedded AVCodecContext instance, which
is used by demuxers to export stream parameters to the caller and by
muxers to receive stream parameters from the caller. It is also used
internally as the codec context that is passed to parsers.
In addition, it is also widely used by the callers as the decoding (when
demuxer) or encoding (when muxing) context, though this has been
officially discouraged since Libav 11.
There are multiple important problems with this approach:
- the fields in AVCodecContext are in general one of
* stream parameters
* codec options
* codec state
However, it's not clear which ones are which. It is consequently
unclear which fields are a demuxer allowed to set or a muxer allowed to
read. This leads to erratic behaviour depending on whether decoding or
encoding is being performed or not (and whether it uses the AVStream
embedded codec context).
- various synchronization issues arising from the fact that the same
context is used by several different APIs (muxers/demuxers,
parsers, bitstream filters and encoders/decoders) simultaneously, with
there being no clear rules for who can modify what and the different
processes being typically delayed with respect to each other.
- avformat_find_stream_info() making it necessary to support opening
and closing a single codec context multiple times, thus
complicating the semantics of freeing various allocated objects in the
codec context.
Those problems are resolved by replacing the AVStream embedded codec
context with a newly added AVCodecParameters instance, which stores only
the stream parameters exported by the demuxers or read by the muxers.
Allow writing an empty channel mask into the wave format header. Useful
if the input file contains an unknown channel layout.
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
Partially undoes commit 2c4e08d89327595f7f4be57dda4b3775e1198d5e:
riff: always generate a proper WAVEFORMATEX structure in
ff_put_wav_header
A new flag, FF_PUT_WAV_HEADER_FORCE_WAVEFORMATEX, is added to force the
use of WAVEFORMATEX rather than PCMWAVEFORMAT even for PCM codecs.
This flag is used in the Matroska muxer (the cause of the original
change) and in the ASF muxer, because the specifications for
these formats indicate explicitly that WAVEFORMATEX should be used.
Muxers for other formats will return to the original behavior of writing
PCMWAVEFORMAT when writing a header for raw PCM.
In particular, this causes raw PCM in WAV to generate the canonical
44-byte header expected by some tools.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
ff_get_wav_header is reading data from a WAVE file and then uses it
(without validation) to malloc a buffer. It then proceeded to read
data into the buffer, without verifying that the allocation succeeded.
To address this, change ff_get_wav_header to return an error if
allocation failed, and adapted all calling code to handle that error.
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
Passing an explicit filename to this command is only necessary if the
documentation in the @file block refers to a file different from the
one the block resides in.
Originally committed as revision 22921 to svn://svn.ffmpeg.org/ffmpeg/trunk
Otherwise doxygen complains about ambiguous filenames when files exist
under the same name in different subdirectories.
Originally committed as revision 16912 to svn://svn.ffmpeg.org/ffmpeg/trunk
The name offset_t is easily confused with the standard off_t type and
*_t is POSIX reserved namespace if any POSIX header is included.
Originally committed as revision 15533 to svn://svn.ffmpeg.org/ffmpeg/trunk
Consistently apply this rule: the guard name is obtained from the
filename by stripping the leading "lib", converting '/' and '.' to
'_' and uppercasing the resulting name. Guard names in the root
directory have to be prefixed by "FFMPEG_".
Originally committed as revision 15120 to svn://svn.ffmpeg.org/ffmpeg/trunk
when building doxygen docs
patch by mark cox melbournemark plus ffmpeg minus devel chez gmail dot com
Originally committed as revision 8866 to svn://svn.ffmpeg.org/ffmpeg/trunk
Thierry Foucu
Anton Khirnov
Carl Eugen Hoyos
Tobias Rapp
Luca Barbato
Michael Niedermayer
Thomas Volkert
Daniel Verkamp
Peter Ross
Diego Biurrun
rogerdpack
Justin Ruggles
Victor Vasiliev
Max Horn
Mans Rullgard
Francesco Lavra
Stefano Sabatini
Carl Eugen Hoyos
Mark Cox