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Andreas Rheinhardt 554b52b1b3 avcodec/mpeg12dec: Remove disabled frame-threading code 
The MPEG-1 decoder has an update_thread_context function set,
yet it was never enabled (missing AV_CODEC_CAP_FRAME_THREADS
flag). So remove it and also the ff_thread_finish_setup() call
as well as the progress reporting.

(Simply setting the flag would not be enough. The main problems
are:
a) The update_thread_context function relies on memcpy'ing
the whole context instead of only copying the necessary fields.
This leads to data races which is undefined behaviour.
(Btw: The check for whether the non-MpegEncContext fields
of Mpeg1Context should be copied has been broken in
7f0efe2324.)
b) Even an AVBufferRef* is simply copied, without creating a new
reference.
c) Copying the whole context happens only during init; when parameters
change lateron, the change is not propagated to the next thread.
This affects at least the quant matrix (for MPEG-1).
d) The MPEG-1/2 decoders are made to decode both MPEG-1 and MPEG-2.
When MPEG-2 is decoded, another complication arises: In case of
coded fields, both fields can be in one AVPacket or they can be
in separate AVPackets. One would need to parse enough of the data
to be able to determine whether the next thread needs to start
a new frame or decode the second field of the current frame;
for this one would need to either postpone calling
ff_thread_finish_setup() for coded slices altogether or implement
some form of ff_h2645_packet_split().
One would also need a second ThreadProgress to signal progress
of each field.
e) One would need to reenable waiting in ff_mpv_reconstruct_mb()
for MPEG-1/2 (and H.261).
f) Probably lots of other stuff for invalid input that I am currently
not thinking about.
If this were done, nothing from the current update_thread_context
would remain, so one can just nuke it altogether.)

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
2025-05-16 01:37:35 +02:00
compat compat/cuda: add device side printf function 2025-05-14 22:08:33 +02:00
doc fftools/graphprint: Now, make it a Killer-Feature! 2025-05-15 23:11:08 +02:00
ffbuild fftools/resources: Add resource manager files with build-time compression 2025-05-15 23:08:05 +02:00
fftools fftools/graphprint: Now, make it a Killer-Feature! 2025-05-15 23:11:08 +02:00
libavcodec avcodec/mpeg12dec: Remove disabled frame-threading code 2025-05-16 01:37:35 +02:00
libavdevice avfoundation: Fix compilation for OSes other than macOS and iOS 2025-04-04 17:12:33 +03:00
libavfilter avfilter/avfilter: Add avfilter_link_get_hw_frames_ctx() 2025-05-15 23:04:44 +02:00
libavformat avformat/matroskadec: check that channels fit in signed 32bit int 2025-05-15 03:03:57 +02:00
libavutil Remove libpostproc 2025-05-07 15:35:47 +02:00
libswresample libs: bump major version for all libraries 2025-03-28 14:44:34 -03:00
libswscale swscale/output: fix integer overflow in yuv2rgba64_full_1_c_template() 2025-05-15 03:03:58 +02:00
presets
tests checkasm: hevc sao, use checkasm_check_padded 2025-05-14 20:55:39 +08:00
tools tools/merge-all-source-plugins: Check that there are no uncommited changes 2025-05-15 16:19:59 +02:00
.gitattributes gitattributes: End merge conflicts in Changelog 2025-03-17 15:26:10 +01:00
.gitignore ffmpeg/repo: Add dot-folders in the repository root to .gitignore 2025-04-19 17:29:12 +02:00
.mailmap mailmap: add entry for myself 2024-07-15 01:59:37 +02:00
Changelog avcodec: add APV encoder using liboapv 2025-05-04 16:21:35 -03:00
configure fftools/resources: Add resource manager files with build-time compression 2025-05-15 23:08:05 +02:00
CONTRIBUTING.md
COPYING.GPLv2
COPYING.GPLv3
COPYING.LGPLv2.1
COPYING.LGPLv3
CREDITS Use https for repository links 2023-03-01 21:59:10 +01:00
INSTALL.md Add tools/merge-all-source-plugins 2025-05-15 12:17:04 +02:00
LICENSE.md Remove libpostproc 2025-05-07 15:35:47 +02:00
MAINTAINERS MAINTAINERS: Add entry for samples-request 2025-05-15 03:03:54 +02:00
Makefile configure: Add wasm as a fake arch 2024-12-04 16:43:06 +08:00
README.md README: fix typo and description of libavfilter 2021-10-08 09:44:34 +05:30
RELEASE RELEASE: update release number after release/7.1 branch 2024-10-09 01:55:50 +02:00

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 means to alter decoded audio and video through a directed graph of connected 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.