DivX to MPEG Bitrate Conversion?

[lazyturbo]

If I know the bitrate for a DivX encoded video, is it possible to know what bitrate to use for MPEG encoding to maintain the same quality? Is there like a bitrate calculator between the 2 formats?

Thanks.

[guns1inger]

There is not equivelent. The best bitrate is the highest bitrate you can fit into the available space. Find your running time, use a bitrate calculator, and go from there. As a general (but by no means scientific) yardstick, mpeg2 usually requires around 4 times the bitrate of Xvid to maintain the original quality.

[lazyturbo]

Hmm...that means that I should convert the MPEG2 to 3000kb/s. Should I use 720x480 or 352x480 when I'm converting at that bitrate?

Thanks.

[guns1inger]

No, you should use the correct bitrate. What resolution really depends on the resolution of the original. Use a bitrate calculator to work out the bitrate.

[jimmalenko]

There is no magic formula.

Sometimes the bitrate determines what frame size we should use, other times the source. It is best to choose the nearest resolution to your source. Choose between 352 * 240/288, 352 * 480/576, or 720 * 480/576 (there may be times when you have a resolution smaller than 352 * 240 - that is OK, you'll just have to use 352 * 240). Your source's frame size can be obtained from GSpot.

Given a perfect (DVD quality 720 * 480/576) source, I use the following:

If ave is < 1000kbps, I'd use 352 * 240/288 2-Pass VBR (min 0 ave ave max 2000)
If ave is > 1000kbps & < 1500, I'd use 352 * 240/288 ave CBR
If ave is > 1500kbps & < 3000, I'd use 352 * 480/576 2-Pass VBR (min 500 ave ave max 5000)
If ave is > 3000kbps & < 4000, I'd use 352 * 480/576 ave CBR
If ave is > 4000kbps & < 8000, I'd use 720 * 480/576 2-Pass VBR (min 1000 ave ave max 9000)
If ave is > 8000kbps, I'd use 720 * 480/576 ave CBR

If a resolution is "forced" because of the source, keep this in mind when perusing the above chart (ie. if your nearest resolution is 352 * 240/288, there is no point using a bitrate > 2000kbps).