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Paul B Mahol 274112c88d avfilter/f_ebur128: add all sample rates support 
The magic constants come from the unofficial "ITU-R BS.1770-1 filter
specifications"¹ by Raiden (libebur128) which relies on "Parameter
Quantization in Direct-Form Recursive Audio Filters"² by Brian
Neunaber.

The constants seem to include a quantization bias, for example:
- Vb is supposed to be exactly √Vh in a high shelf filter
- the Pre-filter Gain should likely be 4dB
- Pre Q and RLB Q are respectively very close to √½ and ½

Those are not adjusted to prevent the values from drifting away from
the official specifications.

An alternative to this approach would be to requantize on the fly as
proposed by pbelkner³, where the 48kHz code path would use the exact
specifications constants while derivating constants for other
frequencies.

[1]: https://www.scribd.com/document/49991813/ITU-R-BS-1770-1-filters
[2]: https://www.scribd.com/document/6531763/Direct-Form-Filter-Parameter-Quantization
[3]: https://hydrogenaud.io/index.php?topic=86116.msg740092#msg740092
2021-07-25 12:15:29 +02:00
compat avfilter: compress CUDA PTX code if possible 2021-06-22 14:05:44 +02:00
doc avfilter/vf_threshold: add support for commands 2021-07-25 11:24:18 +02:00
ffbuild avfilter: compress CUDA PTX code if possible 2021-06-22 14:05:44 +02:00
fftools Remove unnecessary avassert.h inclusions 2021-07-22 15:02:30 +02:00
libavcodec avcodec/h264_sei: parse and export Film Grain Characteristics SEI messages 2021-07-23 11:06:45 -03:00
libavdevice Remove/replace some unnecessary avcodec.h inclusions 2021-07-22 15:29:46 +02:00
libavfilter avfilter/f_ebur128: add all sample rates support 2021-07-25 12:15:29 +02:00
libavformat avformat/yuv4mpegdec: Use table instead of repeated "else if" 2021-07-23 15:05:39 +02:00
libavutil avutil/film_grain_params: add support for H.274 Film Grain Characteristics 2021-07-23 11:06:31 -03:00
libpostproc avcodec/avcodec: Don't include cpu.h 2021-07-22 12:59:07 +02:00
libswresample avutil/internal, swresample/audioconvert: Remove cpu.h inclusions 2021-07-22 14:33:45 +02:00
libswscale avutil/internal, swresample/audioconvert: Remove cpu.h inclusions 2021-07-22 14:33:45 +02:00
presets
tests Remove unnecessary mem.h inclusions 2021-07-22 14:47:57 +02:00
tools tools/graph2dot: Don't use sizeof(AVFilterGraph), check allocation 2021-07-24 05:35:10 +02:00
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.gitignore avfilter: compress CUDA PTX code if possible 2021-06-22 14:05:44 +02:00
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.travis.yml
Changelog avfilter: add afwtdn filter 2021-07-24 12:24:40 +02:00
configure configure: remove sofalizer triggering of avcodec dependency 2021-07-24 17:01:20 +02:00
CONTRIBUTING.md
COPYING.GPLv2
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INSTALL.md
LICENSE.md avfilter/vf_geq: Relicense to LGPL 2019-12-28 11:20:48 +01:00
MAINTAINERS avformat: add Argonaut Games CVG demuxer 2021-05-12 20:25:50 +10:00
Makefile libavresample: Remove deprecated library 2021-04-27 10:43:13 -03:00
README.md
RELEASE Bump Versions before release/4.4 branch 2021-03-20 01:01:12 +01:00

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 a mean to alter decoded Audio and Video through chain of 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.