On Mon, 2003-11-24 at 10:38, Bernhard Praschinger wrote: > But that does not tell you the average bitrate. But you can easly > calculate the average bitrate: > filesize / (number of frame / framerate) = bytes/sec *8 = bits/sec
hello, i am trying to learn how to calculate the bitrate. i encoded a CBR mpeg so i could figure out how to calculate it. i am still off a little bit and dont know why ? the source avi is a DV camcorder capture,NTSC,29.97fps i encoded with this command; $ lav2yuv video.eli | mpeg2enc -o video.m2v from the faq it says if i use these switches i am creating a video file with a default bitrate of 1152kBit/sec. ( VCD) mpeg2enc says i have 3475 frames: INFO: [mpeg2enc] Signalling last frame = 3475 INFO: [mpeg2enc] Frame end 3471 P quant=12.33 total act=177010.51095 INFO: [mpeg2enc] Frame end 3472 B quant=13.69 total act=177042.15341 INFO: [mpeg2enc] Frame end 3473 B quant=13.99 total act=177073.44669 INFO: [mpeg2enc] Frame end 3474 P quant=12.70 total act=177106.62586 INFO: [mpeg2enc] Frame end 3475 B quant=12.65 total act=177136.90095 INFO: [mpeg2enc] Guesstimated final muxed size = 16700455 now i use the formula to figure out what my file size should have been. 3475 frames / 29.97 fps = 115.94 seconds of video and 1152kBit / 8 = 144KByte video bitrate so X (filesize in KBytes) / 115.94 seconds = 144Kbytes video rate X = 16695.36 Kbytes or (16695.36 * 1024) 17096048 bytes but what is have is less than that [EMAIL PROTECTED] capture]$ ls -l video.m2v -rw-rw-r-- 1 rperkins rperkins 16272944 Nov 27 01:53 video.m2v if i plug the actual file size and solve for video rate my rate comes out to 1096.5 Kbps when it was suppossed to be 1152 Kbps i would think this should come out exact ? so where did i go wrong ? thanks randy ------------------------------------------------------- This SF.net email is sponsored by: SF.net Giveback Program. Does SourceForge.net help you be more productive? Does it help you create better code? SHARE THE LOVE, and help us help YOU! Click Here: http://sourceforge.net/donate/ _______________________________________________ Mjpeg-users mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/mjpeg-users
