Whether or not VMAF is the ultimate objective measure of video quality is up for debate (especially when dealing with anime or gaming), but it is one of the best automated quality assessments that we have at present. It does not help with constrained-CRF, but when combined with FFmpeg's plotframes tool could act as a guideline for constrained CRF. It does not attempt to do per scene optimization. The VMAF analysis in the tool operates on samples throughout the file and produces an estimate of the target CRF for the whole file required to achieve a particular VMAF (default is VMAF=95). X264 $ ab-av1 crf-search -encoder libx264 -min-vmaf 95 -pix-format yuv420p -i $Ĭrf 23 VMAF 95.43 predicted full encode size 167.98MiB (64%) taking 23 minutes See help for various options that can be passed to FFmpeg including filters such as -vfilter "scale=width=-2:height=720" $ ab-av1 crf-search -h Install $ brew install rust # Install rust through the preferred mechanism for your OS. I'm sure that those of you who use AV1 will already be familiar with this tool, but for those of us who still use x264/265 in their daily workflows, this is super helpful for simplifying multi-pass VMAF analysis with a single command. It takes the pain way from running multiple VMAF passes. It was originally written for AV1, but has now been extended for other codecs including x264 & x265. This is a cool tool that allows you to run a single command to estimate what CRF is required to target a particular VMAF. If your source is lossy so is your output.The team who produced ab-av1 0.4.0 have recently extended the crf-search mechanism to support non av1 codecs. Note: Video/audio output can only be as good as the video/audio input. To learn more about it and how presets affect the quality or encoding speed, check the H.264 encoding guide on the FFmpeg wiki. To set the quality, use -crf 23, where lower is better, and values from 18-28 are considered a good range.įfmpeg uses libx264's own preset system.
Tests have shown this library functions comparatively if not more efficiently than Apple's Compressor or Episode, although both these programs have powerful features that ffmpeg does not have.
Wikipedia has related information at X264īefore using this in a production system please obtain the necessary licenses, you are warned! Wikipedia has related information at H.264/MPEG-4 AVC It's not natively supported in ffmpeg, so you will need to build ffmpeg with support for the external library, x264. It is heavier on encoding and decoding than preceding formats but results in much higher picture quality from smaller files. It is currently being used in formats such as Blu-ray, MP4, Flash (F4V), HTML5and most modern portable devices.
H.264 is arguably the cutting edge of video compression codecs.
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