Bitrate Calc

[rinkguy]

I make my DivX movies with flask and I calculate the bitrate with DivX birate calculator v. 2.4. Now what I wnat to know is, IS there a calculator that is more accurate, since foe example; I was encoding Aliens the other day, length of the movie is 159 min and 17 secs. I entered the info into the calc and selectes the desired size th fit on 1x700mb disc. All the other options match my criteria in Flask. Now the suggested bitrae was 506kbps. I dropeed this value to 490 kbps cause in the past it Flask seemed to make th file too big to fit on disc. Now after 10 hours of encoding the file was finished and I had my Aliens DivX movie ready, problem is the file was 786 MB! Thats after I dropped 16kbps off the suggested value. I want to know if there is a more accurate calculator out there and is there a way to make my Aliens file smaller without having to reencode it? ( I already trimmed off the extra's) Thanks

[khp]

Hi

What resolution are you using ?.

490kbs is very very low, I think you problem is that, divx simply won't encode at that low a bitrate (divx4.* will respect the MQ mQ settings more than the bitrate).
You might solve your problem by raising the MQ value to 24, but keep in mind your results will look like crap.
with a movie that long I would use at least 2 maybe even 3 CD's.

[rinkguy]

Quality of the DivX is not the problem, the quality is great. the problem is when I use the bitrate calc, it says to make the bitrate 'x' kbps. to fit it one one cd, but the finished product is way over and above the 700mb max. I want a calc that will give the a bitrate that will allow the DivX to fit on 1 CD, and only 1 CD.

[khp]

OK I'll be repeating myself a lot in this post, but this is what you get when you won't listen.

What resolution are you using ?.

490kbs is very very low, unless u use a resolution of 352*xX or below.
The Calculator is not the problem, the problem is that the divx codec has problems with very low bitrates, setting a Higher MQ will allow the codec compress the video more, and should therefore reduce your problem.

As to ways of reduceing filesize without reencoding the video, you could reencode the audio to 64kb, that should give u 55MB, assuming u are using 112kb. Cutting off the endcredits should give u another 30MB.

[rinkguy]

Sorry for not listening, but I just dont understand this stuff. MQ? etc. The video is 720 x 320 which it reads above the video selection when I choose the codec (divx 4.11) and set the bitrate. The video frame size when I crop it in the configure section reads720 x 576. now I just encoded Die hard 3 and the calc said to make the bitrate 636, I set it at 620 and the file ended up 778 MB. I am Happy with the quality and I want it to fit on one disc. What do I do? MQ? what is that?
Thanks, Ill try to listen next time.

[khp]

MQ is short for maximum quantizer, when selecting the bitrate there is an entry for this in the upper right corner.

The maximum quantizer tells the divx codec how much it's allowed to compress the video, and it will respect this setting no matter what bitrate you have set.
The minimum quantizer tells the codec how much it must compress the video.

But with a bitrate of 900-500 I strongly urge you to use a lower resolution, in general you should never go below 0.15-0.20 bits per pixel.

Calculating this is a bit of a hassel, but lets try it with Alien:
bitrate= 490kbs = 490.000 bits per second
Imagesize = 720*320 = 230.400 pixels per frame
Pixels = 230400 * 25 = 5.760.000
BitsPerPixel = 490.000 / 5.760.000 = 0.085

With this kind of numbers you will get much better results at a lower resulution.