VBR vs CBR for maximum playback reliability

[Stephen Mann]

I have never had good results with double-layer DVD’s. Sometimes they play, sometimes they don’t. It’s just the risk of burned DL disks.

Steve Mann
MannMade Digital Video
http://www.mmdv.com

[Mikhail Petrushin]

6960 kbps is a bit low bitrate in my opinion (DVD standard allows use 9800 so any commercial player must handle bitrate up to 9800).

So I’d rather choose VBR settings with Average Birtrate 6960 kbps and Maximum birtate 9800. In this case the video quality on dynamic scenes will be better.

Off: Where do you live Nigel? I’m in Ferny Grove (Brisbane North West)

[John Rofrano]

[Mikhail Petrushin] “So I’d rather choose VBR settings with Average Birtrate 6960 kbps and Maximum birtate 9800. In this case the video quality on dynamic scenes will be better.”

+1

Definitely use VBR. The only time you should use CBR is when your entire video will fit on the disc at 8000Mbps. Anything less and VBR will always give you better results. VBR Two Pass will be even better.

~jr

http://www.johnrofrano.com
http://www.vasst.com

[Jim Prisby]

Verbatim makes DL disks with printable sufaces, order online.

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[Nigel O’neill]

Runcorn on the South side

[Dave Haynie]

9800Kb/s also assumes there’s no audio… most of the time, you want audio. Your 9.8Mb/s is both audio and video, so the first thing you do is to back off from the peak based on whatever audio you’re using.

Yes, any commercial player will handle full 9.8Mb/s. But if that player has trouble reading your disc (the player’s fault, not yours), there’s no margin for retries at full bitrate (well, in theory — in practice, things like PS3s and BD players read DVDs at 2x, so they don’t have an issue). This is why many folks limit video to 8Mb/s.

On anything but talking heads, VBR is the right decision. Yeah, as John says, if you can fit the whole thing at 8Mb/s CBR, you won’t see VBR as a noticeable improvement. But it also doesn’t hurt anything but your time.

DVDR-DL/+DL are a problem for many players. It’s really the technology.. like DVD-R/+R and DVD-RW/+RW before it, these aren’t perfect copies of a glass mastered dual layer disc. The reflectance of the second DVD layer on a glass mastered disc is supposed to be at least 25% (in fact, there was a bug in the early Philips DVD reference code that flagged such a low reflectance disc as dual-layer… unfortunate because DVD-RW is usually around 25%; that’s the only reason many early players didn’t handle the RW discs). It’s about 15-20%, either layer, on a DVDR-DL.

And these came out late. Naturally, the DVD drive you use to burn the discs read them. Some older players have very good AGC circuits that compensate for reflectance in the name of compensating for aging lasers (the main reason for AGC circuits in DVD laser systems). Others simply can’t read these discs — they don’t really meet the original DVD specs.

-Dave

[Nigel O’neill]

Thanks Dave

I will use VBR 2 pass. So far, the discs are being recognised and play on all my home DVD players (Sony, LG, AWA, Teac).

My customers (consumers) in Australia tend to have the el cheapo China made DVD players that seem to play everything.

What sort of issues crop up with DL discs as mine seem to play back fine?