Hallo > I'm encoding an mpeg2 bitstream using the following command: > > mpeg2enc "inputfile" -f 3 -a 2 -b 7500 -q 5 -V 220 -o "outputfile" > > When we use a quantization step (5 in this case), the bitrate used > by the mjpegtools will be a VBR. But I notice that the maximum Small correction as soon as you encode to a MEPG2 Video mpeg2enc uses VBR, It does not matter if you add the -q option. If you don't add the -q option mpeg2enc uses a qaulity factor of of 9 by default.
> bitrate used is not the one we give as a parameter (7500 kbit/s) > which led to poor quality when encoding. Thats unlikely. Which image size and image source do you have ? And which average bitrate do you have when you multiplex the stream afterwards. Did you use any filter. And who is you complete command line would be interresting. Could you send me (and not to the mailinglist) a frame of the source video and one frame from the encoded video to see the difference. > I'm doing a study of the mjpegtools and I have to look into the > witten code to discover why this happen (why the bitrate never > reaches the one specified in the -b field). Thats the way mpeg2 work. If you reach the quality factor you specified with a lower bitrate than the maximum. The bitrate stayes lower. > The idea was to change > the code in order to make the control of the bitrate only when the > maximum bitrate desired was reached because right know it is > controlled right from the beggining, and therefore the 7500 > Kbits/s aren't reached. MPEG1 with CBR (without the -q option) works that way. And it is implemented that way. auf hoffentlich bald, Berni the Chaos of Woodquarter Email: [EMAIL PROTECTED] www: http://www.lysator.liu.se/~gz/bernhard ------------------------------------------------------- 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
