I'm dealing with a very big issue about bit rate , ffmpeg provide the -b option for the bit rate and for adjustment it provide -minrate and -maxrate, -bufsize but it don't work proper. If i'm giving 256kbps at -b option , when the trans-coding finishes , it provide the 380kbps. How can we achieve the constant bit rate using ffmpeg. If their is +-10Kb it's adjustable. but the video bit rate always exceed by 50-100 kbps. I'm using following command ffmpeg -i "demo.avs" -vcodec libx264 -s 320x240 -aspect 4:3 -r 15 -b 256kb \ -minrate 200kb -maxrate 280kb -bufsize 256kb -acodec libmp3lame -ac 2 \ -ar 22050 -ab 64kb -y "output.mp4" When trans-coding is done, the Media Info show overall bit rate 440kb (it should be 320kb). Is their something wrong in the command. Or i have to use some other parameter? Plz provide your suggestion its very important.