Make sure not to use vorbis, which is the (bad) internal encoder.

vbr on is default, -b:a just sets the target, see FFmpeg documentation. Target bitrates are in the ProRes Whitepaper. Corresponds to the profiles Proxy, LT, Std, HQ. q:v works for mpeg4, but haven't tested others. Doubling the value results in half the bitrate. Mpeg1, mpeg2, mpeg4, flv, h263, h263+, msmpeg+Ģ is visually lossless. No VBR by default-it uses -b:v 200K unless specified otherwise. Setting -maxrate and -bufsize is also possible.Ģ is visually lossless. b:v sets target bitrate, or maximum bitrate when -crf is set (enables CQ mode). Specifying -profile:v lets you adjust coding efficiency. Rows in yellow aren’t really VBR or I simply couldn’t find out whether they support it.

Rows highlighted with green refer to encoders that allow you to use VBR.

Read the second column Param for the correct option to use.

Some encoders use private options instead of the regular -q.

I wasn’t able to research whether this applies to all encoders. This means that (most?) encoders will use one or the other VBR mode by default, e.g. Q def is the default value chosen if no other is specified.These are not just lowest and highest values. Q min stands for the setting to be used for achieving lowest quality and Q max for highest.This is an attempt to summarize the most important ones.

The problem is that every encoder uses a different range of values to set the quality-and they’re hard to memorize. Variable bit rate is usually achieved by setting -q:v (or -q:a for audio) instead of -b:v (or -b:a), which just sets a target bit rate. This gives you a much better overall quality when file size or average bit rate are not constrained (e.g. There are various FFmpeg encoders that support variable bit rate / constant quality encoding (learn more about rate control modes here).

Ffmpeg crf quality