In the previous command you tell scale to make the stream 150 pixels wide and to scale its height proportionally. Similarly, for constant quality encoding, you will simply save bitrate by choosing a slower preset.Įxtract images frame by frame from a video file ¶įfmpeg -i example.mp4 -i LM_logo.pngcoding_robots.mp4 -i logo_flu.png -filter_complex ' scale=150:-1, overlay=W-w-10:H-h-10' -codec:a copy coding_marked.mp4 This means that, for example, if you target a certain file size or constant bit rate, you will achieve better quality with a slower preset. A slower preset will provide better compression (compression is quality per filesize). If it looks bad, choose a lower value.Ī preset is a collection of options that will provide a certain encoding speed to compression ratio. If the output looks good, then try a higher value. The range is exponential, so increasing the CRF value +6 results in roughly half the bitrate / file size, while -6 leads to roughly twice the bitrate.Ĭhoose the highest CRF value that still provides an acceptable quality. Consider 17 or 18 to be visually lossless or nearly so it should look the same or nearly the same as the input but it isn’t technically lossless.

A lower value generally leads to higher quality, and a subjectively sane range is 17–28. The range of the CRF scale is 0–51, where 0 is lossless, 23 is the default, and 51 is worst quality possible. crf is the quality, lower means better quality, 15-25 is usually good.Extract images frame by frame from a video fileįfmpeg -i input.mp4 -c:v libx264 -crf 24 -preset slow output.mp4

Ffmpeg compress video to size