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.
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>
To define accurately the delay between two frames, it is necessary to
have both available. Before this commit, the first frame had a delay of
0; while in practice the problem is not visible in most situation, it is
problematic with low frame rate and large scene change.
This commit notably fixes output generated with commands such as:
ffmpeg -i big_buck_bunny_1080p_h264.mov
-vf "select='gt(scene,0.4)',scale=320:-1,setpts=N/TB"
-frames:v 5 -y out.gif
Also, to avoid odd loop delays, the N-1 delay is duplicated for the last
frame.
The encoder now doesn't produce any extra graphic control extension
block anymore. Only the image is encoded, and the muxer writing
its own GCE containing notably the timing information now includes the
optional palette transmitted through packet side data.
This commit avoid setting clashes between the two GCE, and reduce the
size of the generated file with pal8 output.
Extension description comments are now placed along the avio calls, the
always defined macro removed, and the always true loop_count check as
well (loop option is bound to 0-65535).
This commit removes the badly duplicated code between the encoder and
the muxer. That may sound surprising, but the encoder is now responsible
from the encoding of the picture when muxing to a .gif file. It also
does not require anymore a manual user intervention such as a -pix_fmt
rgb24 to work properly. To summarize, output gif are now easier to
generate, code is saner and simpler, and files are smaller (thanks to
the lzw encoding which was unused so far with the default .gif output).
We can certainly make things even better, but this is the first step.
FATE is updated because of the output being produced by the encoder and
not the muxer (no lzw in the muxer), and in the seek test only the size
mismatches.
Fixes Ticket #2262
* commit '3f7fd59d151a2773f0e2e93e56b6b13ec6e5334b':
avformat: fix typo in avformat_close_input
mp3enc: write Xing TOC
mp3enc: support MPEG-2 and MPEG-2.5 in Xing header.
mp3enc: downgrade some errors in writing Xing frame to warnings
lavf: flush the output AVIOContext in av_write_trailer().
lavf: cosmetics, reformat av_write_trailer().
avio: flush the internal buffer in avio_close()
Enhance doc on asyncts audiofilter
cmdutils: avoid setting data pointers to invalid values in alloc_buffer()
libavcodec: remove av_destruct_packet_nofree()
Conflicts:
libavcodec/avpacket.c
libavformat/mp3enc.c
libavformat/nutenc.c
libavformat/utils.c
libavformat/version.h
tests/ref/lavf/voc
tests/ref/lavf/voc_s16
Merged-by: Michael Niedermayer <michaelni@gmx.at>
This is consistent with stdio and is what we want to do in all cases.
Fixes a bug in the voc muxer which didn't flush in write_trailer()
previously. This is the cause of the change in the test results.
* qatar/master:
mpegvideo_enc: only allocate output packet when we know there will be output
Add names for more channel layouts to the channel layout map.
sunrast: Add a sample request for RMP_RAW colormap.
avcodec: do not override pts or duration from the audio encoder
Add prores regression test.
Enable already existing rso regression test.
Add regression test for "sox" format muxer/demuxer.
Add dpx encoding regression test.
swscale: K&R formatting cosmetics for PowerPC code (part I/II)
img2: Use ff_guess_image2_codec(filename) shorthand where appropriate.
Clarify licensing information about files borrowed from libjpeg.
Mark mutable static data const where appropriate.
avplay: fix -threads option
dvbsubdec: avoid undefined signed left shift in RGBA macro
mlpdec: use av_log_ask_for_sample()
gif: K&R formatting cosmetics
png: make .long_name more descriptive
movdec: Adjust keyframe flagging in fragmented files
rv34: change most "int stride" into "ptrdiff_t stride".
Conflicts:
avprobe.c
ffplay.c
libavcodec/mlpdec.c
libavcodec/mpegvideo_enc.c
libavcodec/pngenc.c
libavcodec/x86/v210-init.c
libavfilter/vf_boxblur.c
libavfilter/vf_crop.c
libavfilter/vf_drawtext.c
libavfilter/vf_lut.c
libavfilter/vf_overlay.c
libavfilter/vf_pad.c
libavfilter/vf_scale.c
libavfilter/vf_select.c
libavfilter/vf_setpts.c
libavfilter/vf_settb.c
libavformat/img2.c
libavutil/audioconvert.c
tests/codec-regression.sh
tests/lavf-regression.sh
tests/ref/lavf/dpx
tests/ref/vsynth1/prores
tests/ref/vsynth2/prores
Merged-by: Michael Niedermayer <michaelni@gmx.at>
* qatar/master:
ffmpeg: fix some indentation
ffmpeg: fix operation with --disable-avfilter
simple_idct: remove disabled code
motion_est: remove disabled code
vc1: remove disabled code
fate: separate lavf-mxf_d10 test from lavf-mxf
cabac: Move code only used in the cabac test program to cabac.c.
ffplay: warn that -pix_fmt is no longer working, suggest alternative
ffplay: warn that -s is no longer working, suggest alternative
lavf: rename enc variable in utils.c:has_codec_parameters()
lavf: use designated initialisers for all (de)muxers.
wav: remove a use of deprecated AV_METADATA_ macro
rmdec: remove useless ap parameter from rm_read_header_old()
dct-test: remove write-only variable
des: fix #if conditional around P_shuffle
Use LOCAL_ALIGNED in ff_check_alignment()
Conflicts:
ffmpeg.c
libavformat/avidec.c
libavformat/matroskaenc.c
libavformat/mp3enc.c
libavformat/oggenc.c
libavformat/utils.c
tests/ref/lavf/mxf
Merged-by: Michael Niedermayer <michaelni@gmx.at>
* qatar/master: (28 commits)
mp3enc: write a xing frame containing number of frames in the file
lavf: update AVStream.nb_frames when muxing.
ffmpeg: remove unused variables from InputStream.
doc: update ffmpeg -ar and -ac documentation to reflect reality.
ffmpeg: remove pointless if (nb_input_files)
ffmpeg: merge input_files_ts_offset into input_files.
ffmpeg: merge input_codecs into input_streams.
ffmpeg: drop AV prefixes from struct names.
ffmpeg: deprecate loop_input and loop_output options
gif: add loop private option.
img2: add loop private option.
AVOptions: in av_opt_find() don't return named constants unless unit is specified.
x11grab: replace undocumented nomouse hackery with a private option.
dict: extend documentation.
lls: whitespace cosmetics
docs: Use proper markup for a literal command line option
docs: Remove a remark that isn't relevant any longer
docs: Explain how to regenerate import libraries with MSVC tools
docs: Mention that libraries for MSVC can be built with a cross compiler
docs: Remove old docs that mention setting up a build environment with lib.exe
...
Conflicts:
doc/ffmpeg.texi
doc/general.texi
ffmpeg.c
libavcodec/Makefile
libavcodec/dnxhddata.c
libavformat/mp3enc.c
libavformat/utils.c
libavutil/Makefile
tests/copycooker.sh
Merged-by: Michael Niedermayer <michaelni@gmx.at>
