video bitrate and data rate

[jackhoffskii]

so heres a quick question.. when i see other peoples video files they always provide information like

File Size : 697 MB (or 713,992 KB or 731,127,808 bytes)
Runtime : 00:49:36 (71,363 fr)
Frame Size : 640x272 (2.35:1) [~7:3]
Framerate : 23.976 FPS
Frame Quality : 0.362 bits/pixel
Video Codec : XviD
Video Bitrate : 1513 kb/s
Audio Codec : ac3 (0x2000) Dolby Laboratories, Inc
Audio Bitrate : 448 kb/s (6 ch) CBR
Audio Frequency : 48000 Hz

but when i look at the file properties of the file via winxp's right click->properties->summary it says under the Video subsection

Frame rate: 23frames/second
Data rate: 239kbps
Video sample size: 12 bit
Video compression: XVID

my question is what is the difference between Video Bitrate and Data rate. is there some sort of conversion factor? btw the vid specs provided are specs of the same file

[ntojzan]

Data rate = number of bytes per second (usualy)
Bit rate = number of bits per second

Data rate = Bit rate / 8

Cheers...

[jackhoffskii]

so..
the data rate*8=bitrate but in this case..

239*8=1912 which is significantly larger then bitrate of 1513.. :confused:

[gircobain]

713992 (697mb) / 2976 (49:36) = 239.9 kbytes/s
That's the total bitrate (video + audio)
The first set of specs are a bit off, since (1513+448)/8*2976 = 729492 kb, quite a lot more than the stated file size