External DVD burn speeds - bottlenecks?

[fergwad]

I was using a new version of Toast 8.0.x yesterday (I had previously been using 7.x) and I took note of the new feature that displays the average and actual write speeds of the burning. I was previously under the impression that my 16x-capable sony external dvd burner was able to write 16x speed on my 16x-capable DVD-Rs and DVD+Rs, but apparently I was getting somewhere between 6-8x speed. I ran a couple tests to time the burning process: about 7-8 minutes for a full DVD of data, which is about 8x.

What is keeping me from getting over the 8x hump? According to this website, I need transfer speeds of 22 MB/sec to allow 16x write speeds. A few thoughts...

-I tried USB 2.0 and firewire 400 connections and stayed under 8x on both. Is it the cables? drivers? firmware? ports? If this is the bottleneck, the 8x speed would indicate I'm only getting about 10 MB/sec... which seems rather slow.

-I'm working off a 2004 Ibook G4, 1.07ghz processor, 4200rpm HDD, and 512mb of ram. Running OS X 10.4.11. Would any of these things be the bottleneck?

-I've been using 16x DVD-Rs from Taiyo Yuden, and my external burner is supposed to be capable of 16x writes and reads. I do get that option from Toast when selecting a burn speed. Its possible there is something wrong with my burner, but AFAIR it was taking about 7-8 minutes per full DVD when I first bought it. For some reason, I didn't realize until now that this is not what I should expect from 16x speed.

 

[Creative One]

How much was the burner, was it a value bin? Same goes for the DVD's.... Not sure but some of those figures could be theoretical.

 

[Heb1228]

I've got a 20x burner and actual speeds never get higher than 8-10x. Maybe someone else gets the full theoretical speed, but I agree that it may simply not be possible in real life. Just like Firewire 400 doesn't come close to transferring at true 400 megabits per second. Same with 800 - nowhere close. And USB 2 at 48- Mbps? HA!

You've got good media, I'm guessing a decent drive. I don't know of any way to get it to burn faster.

 

[brentsg]

Most of those drives only achieve the rated speed at the outer perimeter of the disk.

 

[TheStrudel]

Even if that wasn't true, optical media is painfully slow. I have a hard time thinking that your external bus was the bottleneck, because DVD 1X = 10.5 Mbit/s. So 20x = 210 Mbit/s, which I think Firewire is quite capable of - a bit more than half its theoretical maximum. I've experienced the same behavior you describe on DVD burners running on SATA. It is faster there, and some discs burn quite quick, but it certainly doesn't go at 16X the whole way.

 

[fergwad]

How much was the burner, was it a value bin? Same goes for the DVD's.... Not sure but some of those figures could be theoretical.

Its a Sony DVD RW DRU-810A. Don't remember how much I paid, but probably around $100.

I primarily use Taiyo Yuden 16x DVD-R and +R, supposed to better than most.

First google result gave me this review of the performance. Apparently a burn in under 5 minutes is basically unheard of.