DVDRIP Bitrate

[boxy]

How can an hour and a half movie be only 700 MBs and still retain very good quality? The bit rate can be something like 125 kbs and the size 600x250 yet when I burn it to a DVD with VS 12 at 720x480 and 6000kbs it looks very good on my 27" CRT television. Is it because the master/original is such good quality?

[Ken Berry]

It's because you are talking about chalk and cheese. The 700 MB filew uses a highly compressed format -- most likely either DivX or its open-source companion XVid. They are in fact mpeg-4, though they use the .avi extension. They produce high quality, yes, but are meant essentially for final display rather than editing.

A video DVD, on the other hand, is less compressed mpeg-2, which uses much higher bitrates to achieve good quality. To fit 90 minutes of video on a single layer DVD, you would indeed need a bitrate of around 6000 kbps. But converting from mpeg-4 to mpeg-2 means that you will inevitably suffer a quality loss in the conversion. For instance to go from a frame size of 600 x 250 to 720 x 480, the conversion process has to literally invent a lot of pixels out of nothing... So if, as you say, you are getting acceptable quality in that conversion, then good. However, if you used a larger high def TV, I suspect you would notice quite a few conversion artifacts, including very blocky/pixelated blacks in particular...

[boxy]

Chalk and cheese? Oh, that's like saying 'apples and oranges' here in the U.S.

Thanks for your explaination! Much appreciated.