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.
This is necessary to avoid target config settings bleeding into the host
compilation process with hardcoded tables and the DV VLC tables no longer
present as static tables in a header file.
Since 596e5d4783, this is not necessary anymore. It also allows to
actually disable the flushing, improving write performance (but
possibly giving worse latency in real-time streaming).
Signed-off-by: Martin Storsjö <martin@martin.st>
Prefix the functions/tables brktimegm, pcm_read_seek,
dv_offset_reset, voc_get_packet, codec_movaudio_tags,
codec_movvideo_tags.
After this, lavf has no global symbols without the proper prefix.
Signed-off-by: Martin Storsjö <martin@martin.st>
The new function provides a more generic interface than av_fifo_peek()
for peeking at a FIFO buffer data.
Signed-off-by: Anton Khirnov <anton@khirnov.net>
In the name of consistency:
put_byte -> avio_w8
put_<type> -> avio_w<type>
put_buffer -> avio_write
put_nbyte will be made private
put_tag will be merged with avio_put_str
Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>
libavformat/dvenc.c:82: warning: implicit declaration of function ‘brktimegm’
Originally committed as revision 22920 to svn://svn.ffmpeg.org/ffmpeg/trunk
work_chunks_* and dv_idct_factor_* variables appear only once in the binary
instead of 3 times.
Saves 3264 bytes in .rodata and 312416 bytes in .bss on x86_64.
Originally committed as revision 20246 to svn://svn.ffmpeg.org/ffmpeg/trunk
Yes this breaks ABI/API but ive already broken it and will bump avutil major
soon.
Originally committed as revision 17869 to svn://svn.ffmpeg.org/ffmpeg/trunk
libavformat/dvenc.c:256: warning: passing argument 2 of ‘av_fifo_generic_write’ discards qualifiers from pointer target type
Originally committed as revision 16460 to svn://svn.ffmpeg.org/ffmpeg/trunk
patch by Stefano Sabatini, stefano.sabatini-lala poste.it
along with some spelling/consistency fixes for the long names by me
Originally committed as revision 13649 to svn://svn.ffmpeg.org/ffmpeg/trunk
patch by: Björn Axelsson, bjorn d axelsson a intinor d se
thread: [PATCH] Remove static ByteIOContexts, 06 nov 2007
Originally committed as revision 11071 to svn://svn.ffmpeg.org/ffmpeg/trunk
* Making DV codec release a buffer on exit
* Flagging accepted pix_fmts for DV encoder
Originally committed as revision 7531 to svn://svn.ffmpeg.org/ffmpeg/trunk
Vittorio Giovara
Anton Khirnov
Luca Barbato
Diego Biurrun
Clément Bœsch
Martin Storsjö
Stefano Sabatini
Mans Rullgard
Diego Elio Pettenò
Reimar Döffinger
Michael Niedermayer
Aurelien Jacobs
Roman Shaposhnik
Baptiste Coudurier
Björn Axelsson
Corey Hickey
Nicholas Tung
Brian Brice