[jccam]

Two questions about burning dual-layer DVDs with iDVD ’05:

1) When burning single-layer DVDs, I have read that quality decreases if your movie is longer than 1 hour, since iDVD uses a bit rate of 8000 kbits/sec for up to 60 min., and 6000 kbps for up to 90 in., and 4000 kbps for 120 min. Supposedly, it only knows how to burn at those rates. Once you pass each threshold, iDVD kicks into the next rate. For example, a 59 minute movie would burn at 8000 kbps to fill the disc, while a 61 minute movie would kick into the next rate and would burn at 6000 kbps to fill the disc. (Sorry, can’t remember where I read this or I’d link it). So, does anyone know what the burn rates are for a DUAL-layer disc? How long can my movie be if I want to use the least compression possible? I assume it would be “double” that of a single-layer disc—that is, 120 minutes?

2) Are there problems with burning dual-layer DVD from a disc image? Apparently so, since in iDVD ’05 Help, it says “You should always burn double-layer discs directly from iDVD and not from a disc image. Double-layer discs burned from a disc image may cause playback issues in some DVD players, such as freezing during playback.” My question is: suppose I burn a 3-hour movie to a dual layer disc, and then at some later time I want to burn another copy of it? For single layer discs, I would like make a disc image from the DVD with Disk Utility and burn from that. But apparently this is not advised for dual layer. I certainly don’t want to keep the massive source files sitting around on my hard drives. Any advice? Has anyone experienced playback problems with dual-layer DVDs burned from disc images?

Thanks for any advice on these issues.

[mduell]

iDVD should use a bitrate of 9.6Mbps for movies up to one hour (9.6 Mbps * 60 minutes = 4.22 gigabytes), I wonder why it uses the lower bitrate. Even the cheap DVD burning apps for Windows will let you maximize the bitrate for the length of your movie (to hit 4.3GB total).
Dual layer disks aren't quite double the capacity of single layer disks (8.5 and 4.3GB, respectively), but since iDVD is using a lower bitrate (7.81Mbps instead of 9.6Mbps), you shouldn't have a problem; 120 minutes at 8000kbps is only 6.87GB (81% of the capacity of a DL disk).

[k_munic]

that 8Mbps rate is for convenience reason and even that is for some (older) windows machines/players much too much...

other authering tools as ffmpeg or DVDStudio allow individual bitrates but are a bit tricky to use... (or simply too expansive)

that "not from images" advice has - to my knwoledge - to do with the setting of the switching point of dl-media... iDVD is "testing" wether the bitstream "fits" on layer1 ...- (read somewhere, sometimes ;-) )

[jccam]

Well, it seems that iDVD 5 does not support dual-layer burning AT ALL without a stock Apple superdrive. I'm using a Pioneer 110D that I installed myself, then ran Patchburn to get iDVD to recognize it. It recognizes it, but will only burn single layer. Aargh!

I have Toast Titanium 6.0.9 but not sure what I need to do to burn my 2-hour+ iDVD movie. I thought about saving it as a disc image with iDVD and then dragging that image into Toast, BUT iDVD will not save it as a disc image because it exceeds the maximum length! Am I caught in a Catch-22? Man, all I wanna do is take my 2-hour, 10 minute home movie and burn it on to one DVD at decent quality! Seems like a simple request...
Thanks for any help you can give.

[skirbomatic]

A DVD-5 disk by defintion is single layer. A DVD-9 disk is dual layer. You can't burn a 2 hour DVD-9 video disk onto a single layer DVD-5 blank. Well, you can, but this is where the concept of compression takes affect. Compression progams strip out pixels. A DVD-9 disk with standard 720 x 480 pixels must be 'dumbed down' to a lower pixel rate to 'fit' onto a DVD-5 disk. Typically, compression programs will reduce the pixel content to 720 x 240. If that's not enough compression to fit onto the DVD-5 disk, then the compression program will start to withdraw horizontal pixels, taking the disk resolution down to 360x 240.

The above is simplified, and not wholly accurate, but I hope it's enough for you to understand the concept. Software like Toast 7 has a built-in compression feature (formerly known as Popcorn for Toast 6, as an add-on) that will allow you to compress DVD files onto single layer disks.

[jccam]

Skirb,

I think you misunderstand me. I don't want to compress a dual-layer disc onto a single-layer disc. I want to burn my 2hour+ iDVD project onto a dual-layer disc.

Any suggestions?
Thanks

[mduell]

Originally Posted by skirbomatic

A DVD-5 disk by defintion is single layer. A DVD-9 disk is dual layer. You can't burn a 2 hour DVD-9 video disk onto a single layer DVD-5 blank. Well, you can, but this is where the concept of compression takes affect. Compression progams strip out pixels. A DVD-9 disk with standard 720 x 480 pixels must be 'dumbed down' to a lower pixel rate to 'fit' onto a DVD-5 disk. Typically, compression programs will reduce the pixel content to 720 x 240. If that's not enough compression to fit onto the DVD-5 disk, then the compression program will start to withdraw horizontal pixels, taking the disk resolution down to 360x 240.

Why would they cut the resolution, instead of just reducing the bitrate to ~4800kbps and maintaining 720x480?

[msuper69]

Originally Posted by jccam

...
I have Toast Titanium 6.0.9 but not sure what I need to do to burn my 2-hour+ iDVD movie. I thought about saving it as a disc image with iDVD and then dragging that image into Toast, BUT iDVD will not save it as a disc image because it exceeds the maximum length! Am I caught in a Catch-22? Man, all I wanna do is take my 2-hour, 10 minute home movie and burn it on to one DVD at decent quality! Seems like a simple request...
Thanks for any help you can give.

I use the Toast/Popcorn duo to burn 2+ hour video on a single-layer DVD. The quality is good but not great.