Bitrate

[moviebuff2]

Hi everyone

I have 2 AVI files. One has a bitrate of 2011kbps, a size of 368(w) x 288 (h) and a frame rate of 29.95fps; the other, 902kbps and 640 x 256 and 24.95fps.

I think the file with higher bitrate, smaller size and higher frame rate, should look better than the other. But when I watched the files, they looked pretty much the same.

Would someone please help me understand the bitrate (I already read the glossary)?

Thanks

[jimmalenko]

Bitrate is kilobits per second.

So mathematically:

Video 1 has ~ 67kb per frame (~ 106,000 pixels). 0.65 bits per pixel.

Video 2 has ~ 36kb per frame (~ 164,000 pixels). 0.22 bits per pixel.

These are just numbers though. Depends on quality of source, type of motion, etc etc. You watching in Full screen ?

[moviebuff2]

Hi jimmalenko:

Thanks for the info.

Yes, I am watching both in full screen. One is truely full screen (i.e., originally made for TV); the other, widescreen.

Both are DivX made from DVD. The higher-bitrate file's codec is DIV3, the lower-bitrate file has XVID.

Cheers

[thecoalman]

Hi everyone

I have 2 AVI files. One has a bitrate of 2011kbps, a size of 368(w) x 288 (h) and a frame rate of 29.95fps; the other, 902kbps and 640 x 256 and 24.95fps.

The first file is using too high a bitrate for that resolution... 2000 is more than sufficient for MPEG1 at that resolution. Divx will produce files of approximate quality as mpeg1-2 at about 1/5th -1/4th the file size. If that video had originally been encoded at 400-500kbps it should look as good as it does now. Additionally your second video has a lesser framerate which requires less data per second. The second one is probably within the datarate range it should be and I'll guess is probably a newer codec which will produce better quality at a lower rate.

I don't work with Divx so those bitrates I mentioned could be on the low end.So in conclusion your first file is just taking up more disc space than it needs too. One thing to note, if you did a side by side comparison the higher resolution video will produce more detail.

[moviebuff2]

Thanks, thecoalman, for the clarifications.

I know I can always count on this forum for help.

Cheers