2pass vbr,automatic vbr, cbr or cq?

[Mocha]

WHenever I use TMPGEnc to convert 2 22-24 minute divx tv episodes into mpeg2 for burning on a svcd, I will use 2 pass vbr and adjust the average bitrate so I can fit both episodes on one 80 minute cdr...usually the average is around 1950-2100. Max is set to 2520 and minimum to 300.

However, to fit 2 29 minute episodes onto one 80 minute cdr, I would have to reduce the avg bitrate to 1550-1600. SO I might as well burn one episode per one cd so I woun't suffer this video quality loss.

Now my question is, since maximum bitrate isn't a concern since there will be plenty of space on the cdr, is there a point in using 2 pass vbr and setting the average to 2520 as well as the maximum? I wonder if I should just use cbr. Or use automatic vbr or cq vbr and set quality to 100 percent. Never tried those 2 before.

SO my question for experienced users of TMPGEnc is ,what type of setting s do you use when you want the highest quality svcd, and you know whatever setting you use, the entire converted file will fit onto one 80 minute cdr?


Thx

[sterno]

I usually use 2-pass VBR for SVCD, but usually I have something longer than what you're talking about and I use a VBR average bitrate that will almost exactly fill the CD. If you haven't already you could try doing a sample CD with 2x29 using 2-pass VBR, it might be fine depending on the source material.

Some people swear by CQ mode in recent versions of tmgenc, but if you're only going to put 29 minutes on a CD anyway CBR will probably be just as good and will probably encode a little faster. With the extra space you could also try making a high-bitrate XSVCD, though you sacrifice some compatibility when you decide not to follow the standard.

[guitar_george_skank]

I agree. To keep it within SVCD standards, I would just use CBR at 2520. There's no point using VBR because it can't take advantage of a higher bitrate at that level. Some people will argue the fact that VBR is still better because the 2 passes allocate the bits better but personally, I can't see a difference.

This a quote from one of LeeBear's posts that might help explain...

"If you have a file that will fit on one CD with a maximum bitrate then yes you'll probably use a CBR of 2520 kb/s. Althought a VBR encode with 300/2320/2520 kb/s can potentially give you better quality (multipass gives you better motion estimation) it's usually not worth the 4x long encode time and quality difference would be barely noticeable."


GGS.

[Bondiablo]

A couple times now I've seen people say they were using the same bitrate for average and maximum. Won't setting average and maximum to the same value kind of defeat the whole purpose of using vbr, isn't it going to give the exact same results of using cbr?

[banjazzer]

Won't setting average and maximum to the same value kind of defeat the whole purpose of using vbr, isn't it going to give the exact same results of using cbr?

Of course. The average is exactly what will be used. You cannot go higher than the average because the maximum is equal to the average. And no matter what you set the minimum too, it cannot drop below the average, or else the target average bitrate will not be achieved!

VBR is most effective if the average lies roughly in the middle of the max and min.

[Bondiablo]

yeah that's what i thought the first time i saw someone say it but see enough people doing it and you start to wonder if maybe you're missing something.

[banjazzer]

Not only will setting the max and average equal not make any difference to using CBR, it will take twice as long to get an identical result!!!