Tip: online DVD/SVCD/VCD bitrate calculator....

[Dr Mordrid]

IF you don't have any other MPEG bitrate calculator for DVD/SVCD/VCD you can use the online one at GuyGraphics;

http://www.guygraphics.com/dvd/bitratecalculator.html

Dr. Mordrid

[Brian Ellis]

Interesting! I tried it out over a couple of recent projects and it was roughly right. However, it doesn't take into account the subject matter. With MPEG-2, the data recorded in the intermediate frames is very dependent on the differential movements within the frame, compared with the key frame, so that, if there were a lot of movement (e.g., panning racing cars from the side of the track), it may give a too-high bitrate figure. Conversely, if the camera is tripod mounted and looking at a talking head with a plain, static, background, you may be able to squeeze a lot more in at the indicated bitrate. My last project was for a roughly 44 minute SVCD and I made an inspired guess at the bitrate and the mpeg-2 file, from TMPGEnc VBR, came out at exactly 700 Mb. I swore an awful cussword, but went ahead anyway and Movie Factory told me I needed 632 Mb, so I burnt it and it worked! This calculator told me to use 1835 kbit/s average and I actually used 1900. The subject matter possibly had slightly less than average movement.

[Dr Mordrid]

Well....taking into account subject matter and the effects of motion compensation *would* make it a bit more accurate, but I think they did a bang-up job in providing this to their customers.

Dr. Mordrid

[Brian Ellis]

Yes, I agree. Notwithstanding, it is well to state that the results should not be taken as gospel truth and it may be wise to lower them a tad if you know you have a lot of movement (or camera shake ).

[wkulecz]

Since it takes so long to render I just use "worst-case" estimates

8000 Kbps for 1hr
7000 for 1 hr 15 min
6000 for 1.5 hr
5000 for 1hr 45 min
4000 for 2 hr

This always leaves a bit of head room for the bug in DVD Movie Factory where it can't set chapter points in files >4GB.

I ideally one of the encoder parameters would be "total project length" and this would calculate an average bit rate and be a parameter for the VBR encoding.

--wally.

[Brian Ellis]

Wally

This sounds reasonable. The above on-line applet "calculates":

9346 Kbps for 1hr
7922 for 1 hr 15 min
6564 for 1.5 hr
5594 for 1hr 45 min
4867 for 2 hr
and goes haywire for 2 h 15 min !!!

I agree that a little headroom is desirable, not just for the valid reason you stated, but because of unexpected increases in file size (which can and do happen).