Some thoughts about SVCD, CBR, VBR and interlaced

[av-freak]

OK, I think I got it al clear now about SVCD, CBR, VBR and interlaced, but please correct me if I'm wrong:

If disk space really doesn't matter you should use CBR with 2.6 Mbps, because this method simply takes the highest bitrate for every frame.
With this method it is possible to store approx. (650000 / ((2600 / 8) * 60)) = 33 minutes of full quality SVCD. So basically it is good for for instance one episode of a sitcom.

But if you like to store more minutes you can use VBR (2 pass):
Say you would like to store 60 minutes on 700 MB this would give you a CBR of approx. (8 * 700000 / (60 * 60)) = 1556 kbps
This value could be taken for avarage bitrate in 2passVBR. Use 2520 as maximum bitrate and 1150 as minimum (cause I think below 1150 isn't really worth looking at).

Is this correct or is there a better way to determine the average bitrate?

I know that 650Mb isn't really 650000 bytes, that's why I used the word "approx." There are good calculators available on this website, so...this is just a rough calculation.

One other thing: I really don't understand why one should deinterlace, because this method uses only one field (so 480 x 288 or 480 x 240) and therefore you definitely will lose sharpness. I think one of the benefits of SVCD is the contribution of both fields (480 x 576 or 480 x 480). You shouldn't throw that away.


<font size=-1>[ This Message was edited by: av-freak on 2001-10-05 04:51:37 ]</font>

<font size=-1>[ This Message was edited by: av-freak on 2001-10-05 04:52:20 ]</font>

[Truman]

You can use a lower minimum bitrate than 1150, if you do 2pass encoding.
You do not have to deinterlace. SVCD allows interlaced MPEG-2. Only if you want to play the SVCDs on PC, you should deinterlace. But if you want to watch your movies on PC, you will chose DivX anyway.
Your calculation is at the end quite correct, but I guess you missed, that you can fit up to 800MB on a 80min SVCD.
1587kbps (video) +224 kbps (audio),15 frames per GOP, muxed with bbMPEG =60min movie on a 80min CD-R.

[av-freak]

You are right, I was forgotten about the 800Mb on 80 min. Thanks for clearing that up.