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Andreas Rheinhardt 235a5734e0 avcodec/h26[45]_metadata_bsf: Use separate contexts for reading/writing
Currently, both bsfs used the same CodedBitstreamContext for reading and
writing; as a consequence, the state of the writer's context at the
beginning of writing a fragment is exactly the state of the reader after
having read the fragment; in particular, the writer might not have
encountered one of its active parameter sets yet.

This is not nice and may lead to invalid output even when the input
is completely spec-compliant: Think of an access unit containing
a primary coded picture referencing a PPS with id id (that is known from
an earlier access unit/from extradata), then a new version of the PPS
with id id and then a redundant coded picture that is also referencing
the PPS with id id. This is spec-compliant, as the standard allows to
overwrite a PPS with a different PPS in between coded pictures and not
only at the beginning of an access unit. In this scenario, the reader
would read the primary coded picture with the old PPS and the redundant
coded picture with the new PPS (as it should); yet the writer would
write both with the new PPS as extradata which might lead to errors or
to invalid data being output without any error (e.g. if the two PPS
differed in redundant_pic_cnt_present_flag).

The above scenario does not directly translate to HEVC as long as one
restricts oneself to input with nuh_layer_id == 0 only (as cbs_h265
does: it currently strips away any NAL unit with nuh_layer_id > 0 when
decomposing); if one doesn't the same issue as above can happen.

If one also allowed input packets to contain more than one access unit,
issues like the above can happen even without redundant coded
pictures/multiple layers.

Therefore this commit uses separate contexts for reader and writer.

Reviewed-by: Mark Thompson <sw@jkqxz.net>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
2020-07-07 05:07:15 +02:00
compat
doc libavcodec/pgxdec: Add PGX decoder 2020-07-03 23:28:26 +02:00
ffbuild
fftools ffprobe: Allow unknown format private AVOptions 2020-07-02 19:24:56 +01:00
libavcodec avcodec/h26[45]_metadata_bsf: Use separate contexts for reading/writing 2020-07-07 05:07:15 +02:00
libavdevice avdevice/decklink_dec: add support for extracting and outputing klv from vanc 2020-07-03 00:24:59 +02:00
libavfilter dnn_backend_native: Add overflow check for length calculation. 2020-07-06 20:22:30 +08:00
libavformat libavformat/hlsenc: Remove duplicate close of the output stream. 2020-07-06 15:16:45 +08:00
libavresample
libavutil avutil/opt: check return value of av_bprint_finalize() 2020-07-02 21:12:37 +08:00
libpostproc Bump minor versions after branching 4.3 2020-06-08 22:49:04 +02:00
libswresample Bump minor versions after branching 4.3 2020-06-08 22:49:04 +02:00
libswscale swscale: cosmetic fixes 2020-06-14 16:34:07 +01:00
presets
tests dnn-layer-math-unary-test: add unit test for atanh 2020-07-06 12:45:14 +08:00
tools dnn_backend_native_layer_mathunary: add atanh support 2020-07-06 12:45:14 +08:00
.gitattributes
.gitignore
.mailmap mailmap: add entry for myself 2020-06-17 22:11:34 +08:00
.travis.yml
Changelog libavcodec/pgxdec: Add PGX decoder 2020-07-03 23:28:26 +02:00
configure avdevice/decklink_dec: add support for extracting and outputing klv from vanc 2020-07-03 00:24:59 +02:00
CONTRIBUTING.md
COPYING.GPLv2
COPYING.GPLv3
COPYING.LGPLv2.1
COPYING.LGPLv3
CREDITS
INSTALL.md
LICENSE.md
MAINTAINERS MAINTAINERS: remove myself as Twitter maintainer 2020-06-28 12:37:55 -08:00
Makefile
README.md
RELEASE RELEASE: We are after the 4.3 branch point, update for that 2020-06-10 00:20:24 +02:00

FFmpeg README

FFmpeg is a collection of libraries and tools to process multimedia content such as audio, video, subtitles and related metadata.

Libraries

  • libavcodec provides implementation of a wider range of codecs.
  • libavformat implements streaming protocols, container formats and basic I/O access.
  • libavutil includes hashers, decompressors and miscellaneous utility functions.
  • libavfilter provides a mean to alter decoded Audio and Video through chain of filters.
  • libavdevice provides an abstraction to access capture and playback devices.
  • libswresample implements audio mixing and resampling routines.
  • libswscale implements color conversion and scaling routines.

Tools

  • ffmpeg is a command line toolbox to manipulate, convert and stream multimedia content.
  • ffplay is a minimalistic multimedia player.
  • ffprobe is a simple analysis tool to inspect multimedia content.
  • Additional small tools such as aviocat, ismindex and qt-faststart.

Documentation

The offline documentation is available in the doc/ directory.

The online documentation is available in the main website and in the wiki.

Examples

Coding examples are available in the doc/examples directory.

License

FFmpeg codebase is mainly LGPL-licensed with optional components licensed under GPL. Please refer to the LICENSE file for detailed information.

Contributing

Patches should be submitted to the ffmpeg-devel mailing list using git format-patch or git send-email. Github pull requests should be avoided because they are not part of our review process and will be ignored.