Stats file from DVD instead of first pass?

[officerM]

Hi,

I was looking at intervideo's DVD copy, and it seems that they skip the whole first pass encode to generate a stats file, and just analyse the bitrate used in the DVD itself.

Is there a (free preferably) program that can quickly analyse a set of VOBs and generate a stats file for use in a Xvid second pass (to skip the first pass?)

I know MPEG4 and MPEG2 are different, but I figured the content of the movie is really what determines the bitrate used in any given location - ie a still scene uses less and an action scene uses more - so using the compression curve that was used on the DVD and scaling it down should work - right?

[teegee420]

It doesn't work like that. The first pass analyzes the actual visual characteristics of the movie. For example, a slow moving scene where two people are just talking isn't going to require as much bitrate as a fast moving scene with a car chase or martial arts. You have to run the first pass. There's no getting around it. If you're in such a hurry just run a single pass encode. Expect quality to take a major hit as a result.

[adam]

Intervideo DVD Copy is a transcoder. The information it uses is totally different then what an encoder uses, like what you would use to encode to xvid. Transcoders just remove DCT data while reusing motion vector information. That is why they are so fast, and also why they are relatively low quality. Some transcoders do run a preliminary pass to determine how much of the source is made up of DCT data and how much is made up of motion data. This allows it to make a more even transcode, so that it doesn't end up compressing some scenes way more than others. But since all it is doing is analyzing the amount of DCT data in each frame, it is very fast.

Encoding is entirely different. The reason that first pass takes so long is because the encoder is analyzing motion information. That's what takes so long, but its also what makes encoding so much higher quality when downsizing. It is compressing the entire file rather then just DCT data. Anyway, teegee420 already answered your question, the answer is no.