commit: 2c433ff21fe5beda9c28986c33ad8b5bdb869352 Author: Sam James <sam <AT> gentoo <DOT> org> AuthorDate: Sun Dec 11 16:53:02 2022 +0000 Commit: Sam James <sam <AT> gentoo <DOT> org> CommitDate: Sun Dec 11 16:53:02 2022 +0000 URL: https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=2c433ff2
media-video/ffmpeg: add explanation of USE=hardcoded-tables This mostly quotes https://trac.ffmpeg.org/wiki/CompilationGuide ("Performance Tips"). Signed-off-by: Sam James <sam <AT> gentoo.org> media-video/ffmpeg/metadata.xml | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/media-video/ffmpeg/metadata.xml b/media-video/ffmpeg/metadata.xml index 60511928e367..54cb9b3546d3 100644 --- a/media-video/ffmpeg/metadata.xml +++ b/media-video/ffmpeg/metadata.xml @@ -25,7 +25,16 @@ <flag name="gcrypt">Enables gcrypt support: Needed for rtmp(t)e support if openssl, librtmp or gmp is not used.</flag> <flag name="gme">Enables support for <pkg>media-libs/game-music-emu</pkg> for playing various video game music formats.</flag> <flag name="gpl">Build GPL code. Should be enabled unless you require LGPL binaries.</flag> - <flag name="hardcoded-tables">Use pre-calculated tables rather than calculating them on the fly.</flag> + <flag name="hardcoded-tables"> + Use pre-calculated tables rather than calculating them on the fly. + + It results in an increase of approximately 15% in the size of libavcodec, the main library impacted by this change. + It enables savings in table generation time, done once at codec initialization, since by hardcoding the tables, + they do not need to be computed at runtime. However, the savings are often negligible (~100k cycles is a typical number) especially when amortized + over the entire encoding/decoding operation. + + Improvements are being made to the runtime initialization, and so over time, this option will have an impact on fewer and fewer codecs. + </flag> <flag name="iec61883"> Support for FireWire DV/HDV input device using <pkg>media-libs/libiec61883</pkg>.</flag> <flag name="jpegxl">Enable JPEG XL de/encoding via <pkg>media-libs/libjxl</pkg>.</flag> <flag name="kvazaar">Enables <pkg>media-libs/kvazaar</pkg> based HEVC encoder.</flag>
