Questions about VBR and forty-two

[jmusd]

Can someone tell me what exactly VBR does? Can turning on and adjusting the VBR in forty-two make the quality better then leaving it off? And does adjusting that affect the vcd/svcd stanadard format, making it an xvcd/xsvcd?

Thanks

[dj_yerba]

Can someone tell me what exactly VBR does? Can turning on and adjusting the VBR in forty-two make the quality better then leaving it off? And does adjusting that affect the vcd/svcd stanadard format, making it an xvcd/xsvcd?

Thanks

First of all... i hate when people post questions and nobody answers.
second... it seems that some people forget that they were also newbies once. i'm a newbie too so i'll do my best trying to explain this subject.

so... i'm not the best person to answer, but there are things i can explain to you... VBR stands for video bit rate, and this function adjust the level of quality for your final output, but this option becomes available when you use SVCD, not VCD which uses CUSTOM RATE. in 42 ver. 1.02, VBR was set as default on 6, so if you go for the bigger number (31) you'll experience poor quality, so i recomend setting this option to 3 for the best.
as far as i know, if you change the Custom Rate option (VCD 1152 default) to something like 2000 or higher, your file won't be standard VCD no more, so you won't be able to burn this file as vcd in toast, you'll have to use missing mpeg tools to make it bin/cue (for multitrack XA) or img (for disc image option in toast).

hope this may help

[jmusd]

Thank you very much dj_yerba. It definitely makes much more sense to me now!

[tgpo]

Actually I think VBR is variable bit rate. I believe the higher the number the less the quality is, and vice versa. If you select this option your svcd instantly becomes a s(x)vcd and it is no longer standard.

Don't use Toast to burn. It causes more problems! Use Missing Media Burner instead.

[flaffer]

tgpo has it right: it is "variable bit rate". Basically, an algorithim is used to extrapolate from the image what rate would work best given a given quality setting. The rate willp never excede the setting you set it at (say '3') but the bit ratewill most probably dip below that at certain points, depending on the video being sampled.

One thing I do not understand is whether or not VBR works for DVD copies. It is available when I have DVD chosen.....

HTH,

Flaffer

[xtrawidth]

isn't it, the higher the value of vbr, the better the quality, like with MP3s? or are we working with the idea that the higher the value of vbr, the more work the DVD players processor has to do, therefore potentially being detrimental to the cause.

[timbo22]

Ok folks, heres the deal:

VBR = Variable Bit Rate.

Forty allows you to encode in VBR or CBR mode (variable or constant bit rate modes). Constant bit rate means that that each second of film will be be compressed to exactly the bitrate specified. While encoding in CBR may be quicker and simpler, it fails to take advantage of the fact that some seconds of video could use more bandwidth, while others could use less (think action schene with detailed background vs. still black screen or credits). In VBR mode, frames that need more bandwidth will be alloted upto the maximum bandwidth (the bitrate you specify), while frames that dont will be allotted less.

This is where the VBR quality slider comes in. The higher the VBR slider number, the more "liberal" the encoder is with moving away (down) from the maximum bitrate for any given second of video. Therefore the higher the VBR setting, the lower the quality.

With this said however, it is a mistake to think that the VBR setting should then always be at 3 (the lowest setting). While 3 will produce higher quality video than 5 with the same bitrate, 5 with a HIGHER bit rate will likely produce a better quality output. The key here is to figure out how much you can bump up the bitrate over the CBR bit rate to produce output that is the same size. As a general frame of reference Ive found bit rates of 6000-7500 with VBR Quality of 5 to produce nice results (the actual numbers depend on length and detail/action of movie).

Anyway hope this clears things up.

[jmusd]

So then does changing the VBR up or down make it an xsvcd or will it still be a svcd?

jmusd


Posted: 2003 Feb 21 00:54*


So then does changing the VBR up or down make it an xsvcd or will it still be a svcd?
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What determines that is ONLY the Bitrate. Change the bitrate in SVCD(2500) standard to anything else higher or lower will yeild an XSVCD.