![]() ![]() ![]() Note that currently -keyint_min is ignored unless it's the same as -g, so the minimum keyframe interval can't be set on its own. To set a fixed keyframe interval, set both -g and -keyint_min to the same value. Anything up to 10 seconds is considered reasonable for most content, so for 30 frames per second content one would use -g 300, for 60 fps content -g 600, etc. The -g option can be used to set the maximum keyframe interval. This can lead to slow seeking, especially with content that has few or infrequent scene changes. cpu-used values between 7-10 are only available in the realtime mode (though due to a bug in FFmpeg, presets higher than 8 cannot be used via FFmpeg).īy default, libaom's maximum keyframe interval is 9999 frames. usage realtime activates the realtime mode, meant for live encoding use cases (livestreaming, videoconferencing, etc). Enabling row-mt is only faster when the CPU has more threads than the number of encoded tiles. To enable fast decoding performance, also add tiles (i.e. row-mt 1 enables row-based multi-threading which maximizes CPU usage. Lower values mean slower encoding with better quality, and vice-versa. cpu-used sets how efficient the compression will be. Otherwise, use one of the other rate control methods described above. Use this option only if file size and encoding time are more important factors than quality alone. 2 MBit/s.įfmpeg -i input.mp4 -c:v libaom-av1 -b:v 2M output.mkv In this mode, it will simply try to reach the specified bit rate on average, e.g. Libaom-av1 also offers a simple "Average Bitrate" or "Target Bitrate" mode. ![]() Note: Windows users should use NUL instead of /dev/null and ^ instead of \. You can also specify a minimum and maximum bitrate instead of a quality target:įfmpeg -i input.mp4 -c:v libaom-av1 -minrate 500k -b:v 2000k -maxrate 2500k output.mp4 The quality is determined by the -crf, and the bitrate limit by the -b:v where the bitrate MUST be non-zero. 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
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