Divx 5 bitrate/file size question.

[tavius]

Hello:

Just a little question, if I am OK, at a fixed bitrate divx5 must produce equal sized files of two videos of the same length.

My problems is that I am programming an application to do distributed coding usign several PC's. I am feeding each client with chunks of 420 seconds, but the result avi file sizes are between 32 Megabytes and 46 megabytes.

Here is an example: at 908kbps, a 420 second chunk must produce an AVI file of aprox 46.5 megabytes. Ok, i have files of 36.1 megabytes and others of 46.1 megabytes.

Any ideas???? The program feed de clients with the info returned from ICGetState, so all codes in all PC's have the same settings.

Thanks

[DJ Bobo]

you must use 2-pass encoding for accurate size

[tavius]

Yes, I am using two pass encoding and that's the result :-(

[DJ Bobo]

The problem is not from DivX, it is from your application, it's doing something wrong. Or one of the videos is oversaturated.

[Acaila]

The problem with destributed encoding is that it screws the codec's ability to respond to the complexity and motion of the scene in relation to the whole movie. Encoding pieces of 420 seconds and expecting the codec to hit the filesize dead-on is just a delusion, it can't, because it takes time to adjust.
So if you have an easy to compress scene it will be lower filesize, because the codec can't respond fast enough to up the bitrate to compensate, and for a difficult to compress scene it will be the other way around.

Encoding the entire movie on a single machine gives you 100% efficiency for reaching the target filesize. The smaller you make the chunks the computer encodes, the lower your overall efficiency will be. Make them too small and you'll get a final movie that is way off the target you set.

[DJ Bobo]

DivX5 *IS* able to reach the target bitrate even when the video is small. I tried that on many short clips of 90 to 120 seconds, the size came exactly as predicted using 2-pass encoding.

And I approve, encoding the movie the way you done is not good, since the codec will give 908kbps average anyway to any part, which is very bad, since there is parts that deserve 2000kbps and others that deserve only 500kbps!
So encode your movie in one or 2 pieces, not more.