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Rémi Denis-Courmont 910d281b21 lavc/h263dsp: R-V V {h,v}_loop_filter 
Since the horizontal and vertical filters are identical except for a
transposition, this uses a common subprocedure with an ad-hoc ABI.
To preserve return-address stack prediction, a link register has to be
used (c.f. the "Control Transfer Instructions" from the
RISC-V ISA Manual). The alternate/temporary link register T0 is used
here, so that the normal RA is preserved (something Arm cannot do!).

To load the strength value based on `qscale`, the shortest possible
and PIC-compatible sequence is used: AUIPC; ADD; LBU. The classic
LLA; ADD; LBU sequence would add one more instruction since LLA is a
convenience alias for AUIPC; ADDI. To ensure that this trick works,
relocation relaxation is disabled.

To implement the two signed divisions by a power of two toward zero:
 (x / (1 << SHIFT))
the code relies on the small range of integers involved, computing:
 (x + (x >> (16 - SHIFT))) >> SHIFT
rather than the more general:
 (x + ((x >> (16 - 1)) & ((1 << SHIFT) - 1))) >> SHIFT
Thus one ANDI instruction is avoided.

T-Head C908:
h263dsp.h_loop_filter_c:       228.2
h263dsp.h_loop_filter_rvv_i32: 144.0
h263dsp.v_loop_filter_c:       242.7
h263dsp.v_loop_filter_rvv_i32: 114.0
(C is probably worse in real use due to less predictible branches.)
2024-05-22 19:15:39 +03:00
compat avutil/common: Don't auto-include mem.h 2024-03-31 00:08:43 +01:00
doc lavu/hwcontext_qsv: update AVQSVFramesContext to support dynamic frame pool 2024-05-20 09:30:48 +08:00
ffbuild riscv: add Zvbb vector bit manipulation extension 2024-05-11 11:38:49 +03:00
fftools fftools/ffmpeg_filter: Fix leak on error 2024-05-20 14:15:23 +02:00
libavcodec lavc/h263dsp: R-V V {h,v}_loop_filter 2024-05-22 19:15:39 +03:00
libavdevice lavd/v4l2: Use proper field type for second parameter of ioctl() with BSD's 2024-05-08 21:33:32 +02:00
libavfilter avfilter/vf_dnn_detect: Fix null pointer dereference 2024-05-21 18:17:07 +08:00
libavformat avformat/mov: avoid seeking back to 0 on HEVC open GOP files 2024-05-21 18:57:44 -07:00
libavutil avutil/hwcontext_qsv: fix GCC 14.1 warnings 2024-05-21 16:57:46 +08:00
libpostproc avutil/common: Don't auto-include mem.h 2024-03-31 00:08:43 +01:00
libswresample avutil/common: Don't auto-include mem.h 2024-03-31 00:08:43 +01:00
libswscale swscale/riscv: explicitly require Zbb for MIN 2024-05-10 18:59:06 +03:00
presets
tests checkasm: h264dsp: Avoid out of buffer writes when benchmarking 2024-05-21 19:20:06 +03:00
tools tools/target_enc_fuzzer: Only read pix_fmts if its set 2024-05-09 16:17:39 +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: Update my mailmap entry 2024-02-23 00:17:21 +01:00
Changelog Changelog: add DVB compatible information for VVC decoder 2024-05-21 20:20:25 +08:00
configure configure: split ISOBMFF writer helpers into a separate component 2024-05-18 13:21:35 -03:00
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 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 MAINTAINERS: add myself as *BSD maintainer 2024-05-13 03:40:16 +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.