RepoMirrors/ffmpeg
1
0
Fork 0
mirror of https://git.ffmpeg.org/ffmpeg.git synced 2024-12-17 21:14:47 +00:00
Code Issues Projects Releases Wiki Activity
FFmpeg git repo
115,716 Commits 37 Branches 400 Tags 241 MiB
C 90.3%
Assembly 7.8%
Makefile 1.3%
C++ 0.2%
Objective-C 0.2%
Other 0.1%
378d1b06c3
Go to file
Rémi Denis-Courmont 378d1b06c3 riscv: probe for Zbb extension at load time 
Due to hysterical raisins, most RISC-V Linux distributions target a
RV64GC baseline excluding the Bit-manipulation ISA extensions, most
notably:
- Zba: address generation extension and
- Zbb: basic bit manipulation extension.
Most CPUs that would make sense to run FFmpeg on support Zba and Zbb
(including the current FATE runner), so it makes sense to optimise for
them. In fact a large chunk of existing assembler optimisations relies
on Zba and/or Zbb.

Since we cannot patch shared library code, the next best thing is to
carry a flag initialised at load-time and check it on need basis.
This results in 3 instructions overhead on isolated use, e.g.:
1:  AUIPC rd, %pcrel_hi(ff_rv_zbb_supported)
    LBU   rd, %pcrel_lo(1b)(rd)
    BEQZ  rd, non_Zbb_fallback_code
    // Zbb code here

The C compiler will typically load the flag ahead of time to reducing
latency, and can also keep it around if Zbb is used multiple times in a
single optimisation scope. For this to work, the flag symbol must be
hidden; otherwise the optimisation degrades with a GOT look-up to
support interposition:
1:  AUIPC rd, GOT_OFFSET_HI
    LD    rd, GOT_OFFSET_LO(rd)
    LBU   rd, (rd)
    BEQZ  rd, non_Zbb_fallback_code
    // Zbb code here

This patch adds code to provision the flag in libraries using bit
manipulation functions from libavutil: byte-swap, bit-weight and
counting leading or trailing zeroes.
2024-06-11 20:12:37 +03:00
compat
doc lavc: bump minor and add APIchanges entry for new USAC profile 2024-06-08 00:22:36 +02:00
ffbuild
fftools fftools/ffmpeg_mux_init: Fix leak when using non-encoding option 2024-06-11 14:32:25 +02:00
libavcodec riscv: probe for Zbb extension at load time 2024-06-11 20:12:37 +03:00
libavdevice riscv: probe for Zbb extension at load time 2024-06-11 20:12:37 +03:00
libavfilter riscv: probe for Zbb extension at load time 2024-06-11 20:12:37 +03:00
libavformat riscv: probe for Zbb extension at load time 2024-06-11 20:12:37 +03:00
libavutil riscv: probe for Zbb extension at load time 2024-06-11 20:12:37 +03:00
libpostproc
libswresample
libswscale riscv: probe for Zbb extension at load time 2024-06-11 20:12:37 +03:00
presets
tests riscv: probe for Zbb extension at load time 2024-06-11 20:12:37 +03:00
tools tools/decode_simple: Check avcodec_send_packet() for errors on flushing 2024-05-28 03:48:06 +02:00
.gitattributes
.gitignore
.mailmap
Changelog changelog: add entry for xHE-AAC 2024-06-02 18:34:46 +02:00
configure configure: Disable DNN without backend 2024-06-11 19:36:54 +08:00
CONTRIBUTING.md
COPYING.GPLv2
COPYING.GPLv3
COPYING.LGPLv2.1
COPYING.LGPLv3
CREDITS
INSTALL.md
LICENSE.md
MAINTAINERS
Makefile
README.md
RELEASE

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.