Film-Tech Forum ARCHIVE: CD-R burning questions (not "how", but "why")

This is topic CD-R burning questions (not "how", but "why") in forum Film-Yak at Film-Tech Forum ARCHIVE.

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Posted by Joe Redifer (Member # 3) on 01-03-2008, 10:40 PM:

When I burn data on a CD-R that is advertised as 80min/700MB, I find that I can burn about 800MB worth of CD-DA red book audio on to the disc, but only 700MB worth of any other type of data. Surely a file structure for general data cannot take up the extra 100MB. If it does, why is it so inefficient? Why can't I make an 800MB MP3 CD? When I burn a 4.3GB DVD, it doesn't matter what format the data is in (video or whatever), it tops off at 4.3 every time, no exceptions (these discs are marketed as 4.7GB).

Also, what is the point of excessively large lead-in and lead-out tracks? I can kind of understand the point of lead-in tracks, but if the laser goes past a certain point on the disc and there isn't anything there, then common sense says the laser needs to go back. There doesn't need to be a lead out track to tell the controller "This area doesn't have any data, dumbfuck!" If that is actually what the lead out track is for, then why doesn't the lead out track need to be written over the ENTIRE rest of the disc?

If these questions are not answered, I will be sad.

Posted by Scott Norwood (Member # 30) on 01-04-2008, 08:02 AM:

The Yellow Book (data) CD format has greater error-correction ability than the Red Book (music) CD format. This is because the consequences of a read failure are greater in the case of a data CD. The extra space is taken up by extra checksum data, etc.

Posted by Bobby Henderson (Member # 840) on 01-04-2008, 11:48 AM:

Does file cluster size come into play with the capacity difference between a data CD and red book CD?

I remember all the bad things about FAT16 and FAT32 on DOS/Windows hard disc partitions. You could end up with space wasting cluster sizes as big as 64K. As far as Windows partitions go NTFS seems to be much better. I think the cluster sizes are only 4K regardless of how big the hard drive volume may be.

Posted by Bruce Hansen (Member # 281) on 01-04-2008, 07:37 PM:

Scott is correct, there is more error correction data on a data CD. If I remember correctly, there is a copy of TOC recorded in lead-out, in case the TOC in the lead-in gets damaged. There is some digital silence recorded in lead-out, in case your player takes a little time to figure out that it is at the end of the disk.

The difference between the 4.3G and 4.7G figures for DVDs is that the DVD makers used 1000 as 1K, and the recorder makers used 1024 (a power of 2) as 1K.

Posted by Joe Redifer (Member # 3) on 01-05-2008, 12:00 AM:

Yeah, I know about the 1024 vs 1000k issue. Marketing is lame.

I don't know how many people here burn DVDs, but it seems like the less data I put on a DVD, the longer the lead out is. Sometimes it will take nearly 10 minutes just to write the read out for a two minute video. Surely that can't be necessary. I don't think the TOC could be that big (certainly no more than a megabyte, and that would allow for a HUGE TOC). When I do a DVD-RW, I let it write lead out for about 10 seconds, then I abort and force eject the disc. It has worked fine in every player every time. The extra lead out is unnecessary. The DVD Forum is full o' idiots, methinks.

Posted by Daryl C. W. O'Shea (Member # 1303) on 01-05-2008, 12:17 AM:

The original (and possibly current) DVD standards require there to be at least ~1GB of data on the disc. Some players will freak out if this isn't the case, hence the longer lead-out for smaller volumes.

10 minutes for a lead-out? Can't you write the entire disc in 10 minutes?

Posted by Joe Redifer (Member # 3) on 01-05-2008, 12:29 AM:

I usually write my discs a bit more slowly instead of warp speed. Generally I find them to be far more stable that way when doing video (tends to play without skipping in more players). For data DVDs, I wouldn't think the speed would matter too much. With the DVD-RW, you have no choice but to write it slowly. With Dual Layer DVDs, I am forced to write at 2.4x or some weird speed like that.

Posted by Chris Slycord (Member # 4239) on 01-05-2008, 12:49 AM:

quote: Bruce Hansen
The difference between the 4.3G and 4.7G figures for DVDs is that the DVD makers used 1000 as 1K, and the recorder makers used 1024 (a power of 2) as 1K.

Reminds me of the time where I saw a "Who wants to be a millionaire" episode. The question was "How many kilobytes are in a megabyte?" and from a computer science perspective, none of the choices were correct.

Posted by Jim Cassedy (Member # 4115) on 01-06-2008, 09:38 AM:

quote: Chris Slycord
Reminds me of the time where I saw a "Who wants to be a millionaire" episode. The question was "How many kilobytes are in a megabyte?" and from a computer science perspective, none of the choices were correct.

Hahahaha! I was sick in bed one day and happened to catch that show episode & question too. It had me scratching my head for a few seconds trying to make sense of their answer choices, which as you said were really all technically incorrect.

Posted by Chris Slycord (Member # 4239) on 01-06-2008, 12:13 PM:

Yeah, because of the hard drive manufacturers using "GB = 1000 MB" and confusing the hell out of the consumers, some people have proposed using "kilobyte = 1000 bytes" and "kibibyte = 2^10 bytes". (kibibyte is short for kilo binary byte).

The IEC decided to use these prefixes a long time ago but hardly anyone in industry has adopted them.