On Tue, May 12, 2015 at 11:47 AM, Henk D. Schoneveld <[email protected]> wrote: > Would you be so kind to explain why to NOT use the crf option?
CRF is essentially a constant quality mode, which results in variable bitrate depending on the spatiotemporal complexity of the scenes. For streaming purposes, this is not ideal, since your adaptive streaming client assumes that a segment encoded at a target bitrate of x kBit/s is can actually be transmitted over a link with x kBit/s throughput. If you want to make sure you're not exceeding a certain bandwidth, the VBV encoding mode is probably the best option (see also https://trac.ffmpeg.org/wiki/EncodingForStreamingSites). Therefore, set -maxrate and -bufsize. A single-pass constant bitrate will not generally be more stable than CRF, but it should be less spikey. See this chart for a comparison between CRF, single-pass CBR and single-pass CBR with -maxrate set: http://i.imgur.com/GxTW4Jy.png y-axis is the frame size, moving average of 120 frames. _______________________________________________ ffmpeg-user mailing list [email protected] http://ffmpeg.org/mailman/listinfo/ffmpeg-user
