cuda - Enable support for various GPU-accelerated filters using NVIDIA PTX compiled with llvm-core/clang
dav1d - Enable AV1 decoding support via media-libs/dav1d
debug - Enable extra debug codepaths, like asserts and extra output. If you want to get meaningful backtraces see https://wiki.gentoo.org/wiki/Project:Quality_Assurance/Backtraces
doc - Add extra documentation (API, Javadoc, etc). It is recommended to enable per package instead of globally
encode - Add support for encoding of audio or video files
fdk - Enable AAC (Advanced Audio Coding) encoding support via media-libs/fdk-aac in addition to FFmpeg's own implementation (warning: if USE=gpl is enabled, this produces a non-redistributable build)
fftools_aviocat - cat's a URL to another one, useful for dumping streams.
fftools_qt-faststart - Rearranges a Quicktime file to facilitate network streaming.
fftools_sidxindex - Write an MPD file for fragmented MP4 files with a sidx index at the start of the file.
fftools_trasher - Writes burts of random data into a file. Great for testing error robustness/resilience/concealment.
flite - Enable text-to-speech filter support via app-accessibility/flite
fontconfig - Support for configuring and customizing font access via media-libs/fontconfig
frei0r - Enable use of filters through media-plugins/frei0r-plugins
fribidi - Enable Bidi support for the drawtext filter via dev-libs/fribidi
gcrypt - Enable using dev-libs/libgcrypt for rtmp(t)e support (not needed if using any of USE=gmp,librtmp,openssl), and for obtaining random bytes (not needed if USE=openssl)
gme - Enables various game music formats support via media-libs/game-music-emu
gmp - Add support for dev-libs/gmp (GNU MP library)
gnutls - Prefer net-libs/gnutls as SSL/TLS provider (ineffective with USE=-ssl)
gpl - Enable use of GPL licensed code, should be kept enabled unless LGPL binaries are needed
gsm - Add support for the gsm lossy speech compression codec
iconv - Enable support for the iconv character set conversion library
iec61883 - Enable FireWire DV/HDV input device support via media-libs/libiec61883
ieee1394 - Enable FireWire/iLink IEEE1394 support (dv, camera, ...)
jack - Add support for the JACK Audio Connection Kit
jpeg2k - Support for JPEG 2000, a wavelet-based image compression format
kvazaar - Enable H.265/HEVC encoding support via media-libs/kvazaar
ladspa - Enable the ability to support ladspa plugins
lcms - Enable ICC profile support via media-libs/lcms
libaom - Enable AV1 de/encoding via media-libs/libaom (warning: this is the reference implementation and is slower than the alternatives)
libaribb24 - Enable ARIB text and caption decoding via media-libs/aribb24
libass - SRT/SSA/ASS (SubRip / SubStation Alpha) subtitle support
libcaca - Add support for colored ASCII-art graphics
libilbc - Enable internet Low Bitrate Codec de/encoding support via media-libs/libilbc
libplacebo - Enable use of GPU-accelerated filters from media-libs/libplacebo
librtmp - Enable Real Time Messaging Protocol support via media-video/rtmpdump in addition to FFmpeg's own implementation
libsoxr - Enable use of the audio resampler from media-libs/soxr
libtesseract - Enable Optical Character Recognition (OCR) filter support via app-text/tesseract
lv2 - Enable use of filters through media-libs/lv2
nvenc - Add support for NVIDIA Encoder/Decoder (NVENC/NVDEC) API for hardware accelerated encoding and decoding on NVIDIA cards (requires x11-drivers/nvidia-drivers)
