Why Does Burning In Dl Mode On A Single-layer Dvd Work?

[Graham Samuel]

I had a problem that Toast couldn't write a 90-minute TV programme (exported from EyeTV) onto a nominally 4.7 Gb single-layer DVD. I got a message "There is not enough space on this disc". In the Knowledge Base I found article 000039T which solved the problem, but now I want to know why it worked. The recommendation was to create a disc image suitable for a dual-layer disc and then burn that to a single-layer one. Logically this seems crazy - dual-layer discs have greater capacity than single-layer ones, therefore why would the process of preparing for a DL disc make my data smaller? Can anyone explain this? Also, can anyone explain why my other attempts to make the video data smaller by reducing the encoding (lower standard of encoding) had no effect at all, in that the amount of data to be written appeared to stay exactly the same. Some mystery here.

 

TIA

 

Graham

[tsantee]

Thanks for these thoughts. Yes, I noticed that I had 4.38 available, and my programme turned out to be 4.44Gb. When I told Toast to reduce the precision of encoding, absolutely nothing happened to the amount of space required, and indeed when I tried to trim a bit off the beginning and end of the prog and made a mistake, only saving the short sections I'd intended to cut out, AFAICS I still needed 4.44Gb, which doesn't make a lot of sense. I may be doing something wrong, but I just don't know what. It's difficult to reconstruct this now - I will see if Wikipedia can help, but I still don't understand why requantizing should be needed when a DL disk offers over 5Gb of data in the first place. I wonder if anyone from Roxio can explain this.

When you start with an EyeTV video then you already have the video in MPEG 2 format. Toast won't re-encode the MPEG 2 video unless you select Always with the button next to re-encode in the custom encoder setting window. So changing the bit rate settings makes no difference unless you also select Always Re-encode.

 

If the MPEG 2 video from EyeTV is greater than 4.38 GB then it is too big for a single-layer disc unless it is re-encoded or unless you do the steps involving requantizing the DL-sized disc image as you've done. However, trimming the length of the video should reduce its size. I don't know if Toast properly recognizes the new size of the video trimmed in Toast, but it should. Personally, I recommend trimming the video in EyeTV before sending to Toast. In this case the new size is certain to be correct in Toast. Regardless, saving as disc image will reflect the trimmed size which – if less than 4.38 GB – can be burned to DVD without requantizing.

 

I recommend checking your settings in EyeTV. You should be able to record 120 minutes of video to a size that fits a single-layer disc in the first place.

 

 

 

[tsantee]

Hopefully Wikipedia has info about how it works to "requantize" video. That's what it's called when Toast changes the quantization of the original MPEG 2 file's compression. Requantizing (I'm loving this word) is different from re-encoding in that it is faster and results in less loss to picture quality.

 

Your 90-minute EyeTV programme recorded at EyeTV's standard setting should easily fit a single-layer disc.

 

The available space on a 4.7 GB disc is actually 4.38 GB.

[Graham Samuel]

Hopefully Wikipedia has info about how it works to "requantize" video. That's what it's called when Toast changes the quantization of the original MPEG 2 file's compression. Requantizing (I'm loving this word) is different from re-encoding in that it is faster and results in less loss to picture quality.

 

Your 90-minute EyeTV programme recorded at EyeTV's standard setting should easily fit a single-layer disc.

 

The available space on a 4.7 GB disc is actually 4.38 GB.

 

Thanks for these thoughts. Yes, I noticed that I had 4.38 available, and my programme turned out to be 4.44Gb. When I told Toast to reduce the precision of encoding, absolutely nothing happened to the amount of space required, and indeed when I tried to trim a bit off the beginning and end of the prog and made a mistake, only saving the short sections I'd intended to cut out, AFAICS I still needed 4.44Gb, which doesn't make a lot of sense. I may be doing something wrong, but I just don't know what. It's difficult to reconstruct this now - I will see if Wikipedia can help, but I still don't understand why requantizing should be needed when a DL disk offers over 5Gb of data in the first place. I wonder if anyone from Roxio can explain this.