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Rémi Denis-Courmont 0e32192548 lavu/riscv: do not fallback to AT_HWCAP auxillary vector 
If __riscv_hwprobe() fails, then the kernel version is presumably too
old. There is not much point falling back to the auxillary vector.

- The Linux kernel requires I, so the flag is always set on Linux, and
  run-time detection is unnecessary. Our RISC-V assembler does anyway not
  support targets without I.

- Linux can compile with or without F and D, but it cannot perform
  run-time detection for them (a kernel with F support will not boot a
  processor without F). The run-time detection is thus useless in that
  case. Besides F and D extensions are used throughout the C code, so
  their run-time detection would not be practical.

- Support for V was added in a later kernel version than riscv_hwprobe(),
  so the system call will always be available if the kernel supports V.
  The only exception would be vendor kernel forks, but those are known to
  haphasardly pretend to support V on systems without actual V support, or
  with only pre-ratification binary-incompatible version. Furthermore, a
  large chunk of our optimisations require Zba and/or Zbb which cannot be
  detected with HWCAP in those kernels.

For what it is worth, OpenJDK already took a similar action. Note that this
keeps AT_HWCAP usage for platforms with neither C run-time <sys/hwprobe.h>
nor kernel <asm/hwprobe.h>, notably kernels other than Linux.
2024-07-22 19:43:51 +03:00
compat avutil/common: Don't auto-include mem.h 2024-03-31 00:08:43 +01:00
doc doc/filters: fix outpad labels in libvmaf_cuda example 2024-07-22 13:00:04 +05:30
ffbuild riscv: add Zvbb vector bit manipulation extension 2024-05-11 11:38:49 +03:00
fftools fftools/ffmpeg_filter: use the correct specifier for crop arguments 2024-07-18 23:27:20 -03:00
libavcodec avcodec/vvc: Add aarch64 neon optimization for ALF 2024-07-22 21:09:56 +08:00
libavdevice avdevice/dshow_capture: Fix error handling in ff_dshow_##prefix##_Create() 2024-07-15 01:59:40 +02:00
libavfilter avfilter/vf_xfade: Check ff_inlink_consume_frame() for failure 2024-07-21 17:02:14 +02:00
libavformat avformat/xmv: Check this_packet_size 2024-07-21 17:02:12 +02:00
libavutil lavu/riscv: do not fallback to AT_HWCAP auxillary vector 2024-07-22 19:43:51 +03:00
libpostproc avutil/common: Don't auto-include mem.h 2024-03-31 00:08:43 +01:00
libswresample swresample/swresample: Rectify invalid function in the documentation 2024-07-02 21:57:17 +02:00
libswscale swscale/output: Fix integer overflows in yuv2rgba64_X_c_template 2024-07-21 15:35:08 +02:00
presets
tests checkasm/h264dsp: test TX bypass 2024-07-21 22:36:48 +03:00
tools tools/target_dec_fuzzer: Adjust threshold for RV30 2024-07-16 18:43:15 +02:00
.gitattributes lavf/assenc: normalize line endings to \n 2024-02-11 17:01:07 -08:00
.gitignore gitignore: add config_components.h 2022-03-17 18:35:41 -03:00
.mailmap mailmap: add entry for myself 2024-07-15 01:59:37 +02:00
Changelog Changelog: mention cropping support in Matroska and MP4 2024-07-11 21:35:40 -03:00
configure configure: Fix Apple framework dependencies in .pc file 2024-07-16 22:50:41 +08:00
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
LICENSE.md avfilter/vf_geq: Relicense to LGPL 2019-12-28 11:20:48 +01:00
MAINTAINERS MAINTAINERS: add myself as d3d12va_encode maintainer 2024-07-10 18:10:08 +02:00
Makefile riscv: add Zvbb vector bit manipulation extension 2024-05-11 11:38:49 +03:00
README.md README: fix typo and description of libavfilter 2021-10-08 09:44:34 +05:30
RELEASE RELEASE: update after 7.0 branch 2024-04-02 13:02:39 -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 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.