On Thu, 2003-12-18 at 20:23, Steven M. Schultz wrote: > You can set the bitrate to 9000 kbits/sec but with a high '-q' the > encoder will only use a fraction of the maximum bitrate. Lower -q > and watch the encoder come closer to the maximum rate. > You set the maximum bitrate and then adjust -q so that the Average > is ~10% lower than the Peak rate.
You mean that for whole movies (> 1 hour) or for smaller scenes? I did some quite extensive tests. I played around with -q, while encoding the same stuff (DV files captured via digital camcorder) either all-movie-in-one-big-MPEG2, or each-scene-in-its-own-MPEG2, then muxing whatever files i got while watching the bitrate report. The results? If i set -q so that the average is 10% lower than peaks for the whole movie thing, there will be scenes (not just a second or two, but entire scenes) where the bitrate will be pressed hard into the ceiling. Usually, in that case, if i increase -q by 1, then those individual scenes will get into the "average is lower by 10% than peak" zone, while on the whole movie the average will be like 25% lower. I am not exactly sure what's going on with those "bitrate crushed into the ceiling" scenes, but there's something weird about them. All bugs everywhere in the video chain (recording, processing, storing, playing) tend to be much easier revealed by them. E.g., mplex reports the average being higher than the peak. :-) Note: by "scene" i mean the interval between two Stops or Pauses when recording the movie with the camcorder. I use that thing as some sort of sui-generis video unit, because when i author my DVDs quite often i put each scene into its own chapter on the DVD. -- Florin Andrei http://florin.myip.org/ ------------------------------------------------------- This SF.net email is sponsored by: IBM Linux Tutorials. Become an expert in LINUX or just sharpen your skills. Sign up for IBM's Free Linux Tutorials. Learn everything from the bash shell to sys admin. Click now! http://ads.osdn.com/?ad_id=1278&alloc_id=3371&op=click _______________________________________________ Mjpeg-users mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/mjpeg-users
