DivXToDVD Encode Bit-Rate



I thought a typical DVD5 should handle about 1.5-2hrs of decent quality MPEG-2 data. More than this (i.e. encoded @<3000kbits/s) and the encode introduces significant quality reduction compared to the source.

Therefore, using DivXToDVD on an XviD of length 1hr45mins I expected an encode to almost fill a DVD5, using as high a possible encoded bit-rate. But it barely filled half (2.1Gig). How is that possible without a low, low bit-rate?

On the plus side, the quality was excellent which worries me even more.

To get 1hr45mins MPEG-2 encoded into 2Gig, should have looked about half as good as the original source shouldn’t it?


The output bitrate fit the source bit rate ( to make it short ) …
so it means we considered the output size doesn’t need to take more space on the specific case of your file. post processing could be make , it is planned for later version.
did you encounter any playback problem ?


No problem at all but I still don’t understand what you have come up with here!
(Have you heard of the saying “Too good to be true”?)…

…The way traditional conversion encodes work is to take the output of the source codec and ‘re-sample’ that for the encode. Usually that means to get a faithfull copy of the output of the source codec you still need to use the highest bit-rates MPEG-2 as possible.

For example, in a frame of XviD lets say the pixel @100x100 was incorrect compared to the source due to the ‘loss behaviour’ of the codec.

When DivXToDVD ‘samples’ that frame for an MPEG-2 encode, it has no way of knowing that it is pixel 100x100 that isn’t faithfull to the source due to XviD. It can’t tell MPEG-2 that it should use pixel 100x100 as an MPEG-2 artifact!!!

Simply, if a low-bit rate for MPEG-2 is chosen, the MPEG-2 encode WOULD create MORE incorrect pixels due to MPEG-2 compression.
(For simple example, you have pixel 100x100 incorrect due to XviD compression and say pixel 700x100 incorrect due to MPEG-2 compression.)

What I am saying is that usually selecting a bit-rate that you guys use for MPEG-2 (averages@<3000kbits/s in general) causes lots of these artifacts due to MPEG-2 compression.

How is it possible that yours doesn’t?
Is it something more to do with resolution?
If so does DivXToDVD drop lines to fit a specific low resolution DVD standard?

Just want to understand this thing 'cos I’ve worked hard to understand re-encoding before!!!