This method is useful for bulk encoding videos in a generally consistent fashion.įfmpeg -i input.mp4 -c:v libaom-av1 -crf 30 -b:v 2000k output.mkv Libaom-av1 also has a constrained quality (CQ) mode that will ensure that a constant (perceptual) quality is reached while keeping the bitrate below a specified upper bound or within a certain bound. A CRF value of 23 yields a quality level corresponding to CRF 19 for x264 ( source), which would be considered visually lossless. Lower values mean better quality and greater file size. b:v MUST be 0.įfmpeg -i input.mp4 -c:v libaom-av1 -crf 30 -b:v 0 av1_test.mkv To trigger this mode, you must use a combination of -crf and -b:v 0. If you do not need to achieve a fixed target file size, this should be your method of choice. Libaom-av1 has a constant quality (CQ) mode (like CRF in x264 and x265) which will ensure that every frame gets the number of bits it deserves to achieve a certain (perceptual) quality level, rather than encoding each frame to meet a bit rate target. Note: Users of libaom older than version 2.0.0 will need to add -strict experimental (or the alias -strict -2). For options that can be passed via -aom-params, checking the -help output of the aomenc application is recommended, as there is currently no official online reference for them. Libaom offers the following rate-control modes which determine the quality and file size obtained:įor a list of options, run ffmpeg -h encoder=libaom-av1 or check FFmpeg's online documentation. To install FFmpeg with support for libaom-av1, look at the Compilation Guides and compile FFmpeg with the -enable-libaom option. libaom is based on libvpx and thus shares many of its characteristics in terms of features, performance, and usage. It was also used for research during the development of AV1. Libaom ( libaom-av1) is the reference encoder for the AV1 format.
This guide currently focuses on libaom and SVT-AV1.
There are currently three AV1 encoders supported by FFmpeg: libaom (invoked with libaom-av1 in FFmpeg), SVT-AV1 ( libsvtav1), and rav1e ( librav1e).
Depending on the use case, AV1 can achieve about 30% higher compression efficiency than VP9, and about 50% higher efficiency than H.264.
AV1 is an open source & royalty-free video codec developed by the Alliance for Open Media (AOMedia), a non-profit industry consortium.
0 kommentar(er)
