Whats the difference between Constant Quantizer and Constant Quality?
These two modes are variations on the generic idea of “unknown bitrate, known quality” where the encoder aims to encode to a specified quality level. This is opposed to the normal “known bitrate, unknown quality” model where the encoder is given an average bitrate and must produce the best file possible with that. The advantage of the former is obviously that the quality can be precisely set, while the latter allows precise filesize control. Which one is right for you is your decision. Note that a 1pass constant quality/quantizer encode will not look as good as a 2pass encode to the same filesize. In x264, there are two modes of “known quality”, Constant Quantizer (CQ) and Constant Quality (aka CRF, Constant Ratefactor). • Constant quantizer: every frame is encoded with a mathematically identical quantizer. Constant quantizer produces a file that for the x264 program is of perfect constant quality (it would be ‘interpreted’ in a similar fashion by other video encoder programs). • Const
