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Andreas Rheinhardt b4f5201967 avfilter: Replace query_formats callback with union of list and callback 
If one looks at the many query_formats callbacks in existence,
one will immediately recognize that there is one type of default
callback for video and a slightly different default callback for
audio: It is "return ff_set_common_formats_from_list(ctx, pix_fmts);"
for video with a filter-specific pix_fmts list. For audio, it is
the same with a filter-specific sample_fmts list together with
ff_set_common_all_samplerates() and ff_set_common_all_channel_counts().

This commit allows to remove the boilerplate query_formats callbacks
by replacing said callback with a union consisting the old callback
and pointers for pixel and sample format arrays. For the not uncommon
case in which these lists only contain a single entry (besides the
sentinel) enum AVPixelFormat and enum AVSampleFormat fields are also
added to the union to store them directly in the AVFilter,
thereby avoiding a relocation.

The state of said union will be contained in a new, dedicated AVFilter
field (the nb_inputs and nb_outputs fields have been shrunk to uint8_t
in order to create a hole for this new field; this is no problem, as
the maximum of all the nb_inputs is four; for nb_outputs it is only
two).

The state's default value coincides with the earlier default of
query_formats being unset, namely that the filter accepts all formats
(and also sample rates and channel counts/layouts for audio)
provided that these properties agree coincide for all inputs and
outputs.

By using different union members for audio and video filters
the type-unsafety of using the same functions for audio and video
lists will furthermore be more confined to formats.c than before.

When the new fields are used, they will also avoid allocations:
Currently something nearly equivalent to ff_default_query_formats()
is called after every successful call to a query_formats callback;
yet in the common case that the newly allocated AVFilterFormats
are not used at all (namely if there are no free links) these newly
allocated AVFilterFormats are freed again without ever being used.
Filters no longer using the callback will not exhibit this any more.

Reviewed-by: Paul B Mahol <onemda@gmail.com>
Reviewed-by: Nicolas George <george@nsup.org>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
 		2021-10-05 17:48:25 +02:00
compat Replace all occurences of av_mallocz_array() by av_calloc() 2021-09-20 01:03:52 +02:00
doc examples/qsvdec: Don't use stack packet 2021-10-03 20:50:50 +02:00
ffbuild avfilter: compress CUDA PTX code if possible 2021-06-22 14:05:44 +02:00
fftools fftools/ffmpeg, doc/examples: Remove redundant av_packet_unref 2021-10-03 20:50:49 +02:00
libavcodec avcodec/amrnbdec: move channel_size bellow to avoid array overreads 2021-10-03 12:13:53 +02:00
libavdevice libavdevice/avfoundation.m: fix potential unreleased lock issue 2021-09-17 15:31:40 +02:00
libavfilter avfilter: Replace query_formats callback with union of list and callback 2021-10-05 17:48:25 +02:00
libavformat avformat/{isom,mov,movenc}: add support for CMAF DASH roles 2021-10-04 17:55:27 +03:00
libavutil avutil/md5: Avoid av_unused variable 2021-10-02 17:13:57 +02:00
libpostproc libpostproc/postprocess_template: Don't reimplement FFSWAP 2021-10-02 17:13:42 +02:00
libswresample swresample/aarch64: fix relocation out of range error 2021-09-25 21:55:29 +03:00
libswscale swscale/swscale: Pass slice location into unscaled code also for dst scaling 2021-10-03 20:38:29 +02:00
presets
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tests avformat/{isom,mov,movenc}: add support for CMAF DASH roles 2021-10-04 17:55:27 +03:00
tools tools/target_dec_fuzzer: Adjust threshold for WMV2 2021-09-26 17:22:22 +02:00
.gitattributes fate: add SCC test 2017-01-27 17:06:42 +01:00
.gitignore avfilter: compress CUDA PTX code if possible 2021-06-22 14:05:44 +02:00
.mailmap mailmap: add entry for myself 2021-03-09 02:09:55 +00:00
.travis.yml Merge commit '899ee03088d55152a48830df0899887f055da1de' 2019-03-14 15:53:16 -03:00
CONTRIBUTING.md Add CONTRIBUTING.md 2016-09-18 10:02:13 +01:00
COPYING.GPLv2
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COPYING.GPLv3
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COPYING.LGPLv2.1
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COPYING.LGPLv3
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CREDITS
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Changelog avfilter: add (a)latency filters 2021-10-02 18:49:40 +02:00
INSTALL.md INSTALL.md: Fix Markdown formatting 2019-01-31 10:29:16 -09:00
LICENSE.md avfilter/vf_geq: Relicense to LGPL 2019-12-28 11:20:48 +01:00
MAINTAINERS avformat: add Argonaut Games CVG demuxer 2021-05-12 20:25:50 +10:00
Makefile FATE: add a test for sliced scaling 2021-08-08 19:26:05 +02:00
README.md Remove the ffserver program 2018-01-06 18:31:37 +00:00
RELEASE Bump Versions before release/4.4 branch 2021-03-20 01:01:12 +01:00
configure configure: arm: Don't add -march= to the compiler if no preference was passed 2021-09-21 14:04:28 +03:00

README.md

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.