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Timo Rothenpieler ef2c2a2220 avutil/half2float: use native _Float16 if available 
_Float16 support was available on arm/aarch64 for a while, and with gcc
12 was enabled on x86 as long as SSE2 is supported.

If the target arch supports f16c, gcc emits fairly efficient assembly,
taking advantage of it. This is the case on x86-64-v3 or higher.
Same goes on arm, which has native float16 support.
On x86, without f16c, it emulates it in software using sse2 instructions.

This has shown to perform rather poorly:

_Float16 full SSE2 emulation:
frame=50074 fps=848 q=-0.0 size=N/A time=00:33:22.96 bitrate=N/A speed=33.9x

_Float16 f16c accelerated (Zen2, --cpu=znver2):
frame=50636 fps=1965 q=-0.0 Lsize=N/A time=00:33:45.40 bitrate=N/A speed=78.6x

classic half2float full software implementation:
frame=49926 fps=1605 q=-0.0 Lsize=N/A time=00:33:17.00 bitrate=N/A speed=64.2x

Hence an additional check was introduced, that only enables use of
_Float16 on x86 if f16c is being utilized.

On aarch64, a similar uplift in performance is seen:

RPi4 half2float full software implementation:
frame= 6088 fps=126 q=-0.0 Lsize=N/A time=00:04:03.48 bitrate=N/A speed=5.06x

RPi4 _Float16:
frame= 6103 fps=158 q=-0.0 Lsize=N/A time=00:04:04.08 bitrate=N/A speed=6.32x

Since arm/aarch64 always natively support 16 bit floats, it can always
be considered fast there.

I'm not aware of any additional platforms that currently support
_Float16. And if there are, they should be considered non-fast until
proven fast.
2022-08-19 22:09:36 +02:00
compat compat: add msvc windres wrapper 2022-08-13 14:42:52 +02:00
doc doc: fix binary values of SI prefixes 2022-08-18 17:10:42 +02:00
ffbuild
fftools ffprobe: restore reporting error code for failed inputs 2022-08-17 16:46:05 +05:30
libavcodec avutil/half2float: move non-inline init code out of header 2022-08-19 22:09:36 +02:00
libavdevice configure: always enable gnu_windres if available 2022-08-13 14:42:36 +02:00
libavfilter avfilter/vsrc_ddagrab: add options for more control over output format fallback 2022-08-13 15:22:14 +02:00
libavformat mov: Compare frag times in correct time base when seeking a stream without a corresponding sidx 2022-08-19 17:02:55 +01:00
libavutil avutil/half2float: use native _Float16 if available 2022-08-19 22:09:36 +02:00
libpostproc configure: always enable gnu_windres if available 2022-08-13 14:42:36 +02:00
libswresample configure: always enable gnu_windres if available 2022-08-13 14:42:36 +02:00
libswscale swscale/x86/yuv2yuvX: Remove unused ff_yuv2yuvX_mmx() 2022-08-19 12:01:34 +02:00
presets
tests avutil/half2float: adjust conversion of NaN 2022-08-19 22:09:36 +02:00
tools tools: Make sure to create the tools directory before building decode_simple.o 2022-08-17 00:00:50 +03:00
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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.