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.
* qatar/master:
bitstream: Properly promote av_reverse values before shifting.
libavutil/swscale: YUV444P10/YUV444P9 support.
H.264: Fix high bit depth explicit biweight
h264: Fix 10-bit H.264 x86 chroma v loopfilter asm.
Replace DEBUG_SEEK/DEBUG_SI + av_log combinations by av_dlog.
Update copyright year for ac3enc_opts_template.c.
adts: Adjust frame size mask to follow the specification.
movenc: Add RTP muxer/hinter options
movenc: Pass the RTP AVFormatContext to the SDP generation
rtspenc: Add RTP muxer options
rtspenc: Add an AVClass for setting muxer specific options
rtpenc_chain: Pass the rtpflags options through to the chained muxer
rtpenc: Declare the rtp flags private AVOptions in rtpenc.h
sdp: Reindent after the previous commit
rtpenc: MP4A-LATM payload support
avoptions: Add an av_opt_flag_is_set function for inspecting flag fields
sdp: Allow passing an AVFormatContext to the SDP generation
mov: Fix wrong timestamp generation for fragmented movies that have time offset caused by the first edit list entry.
mpeg12: more advanced ffmpeg mpeg2 aspect guessing code.
swscale: split YUYV output out of yuv2packed[12X]_c().
Conflicts:
doc/APIchanges
libavcodec/Makefile
libavcodec/h264dsp_template.c
libavcodec/mpeg12.c
libavformat/aacdec.c
libavformat/avidec.c
libavformat/internal.h
libavformat/movenc.c
libavformat/rtpenc.c
libavformat/rtpenc_latm.c
libavformat/sdp.c
libavformat/version.h
libavutil/avutil.h
libavutil/pixfmt.h
libswscale/swscale.c
Merged-by: Michael Niedermayer <michaelni@gmx.at>
This is enabled with an AVOption on the RTP muxer. The SDP
generator looks for a latm flag in the rtpflags field.
Signed-off-by: Martin Storsjö <martin@martin.st>
Derek Buitenhuis