DVD +/- R/W Questions

[Sakuya]

Hi, I was wondering, what takes up the space in a DVD +/- R/W disc? Like on my DVD-R, it says it has 4.7GB of space but then it can hold up to 120 minutes (I think). So which one matters, space or minutes?

If I wanted to put 9 episodes of this series onto one DVD-R and each episode would be 45 minutes, would it fit even if I lowered the video quality and/or bitrate?

[johns0]

To fit that amount onto one dvd the files would have to be vcd standard(352x240) 1150bps with 48khz mp2 audio at 224kbps.

[Sakuya]

But since each episode is 45 minutes long and I want 9 of them on one DVD-R, that would come out to 405 minutes. Even if all 9 of the files' sizes are under 4.7GB, the episodes are still 405 minutes which is way over the 120 minute limit of the DVD-R. That's what I don't get.

[johns0]

It doesnt matter how long a mpg file is,its the size of the file that matters,120 mins is just an estimate for quality for a mpg,not a standard or limit.In other words its the bitrate that counts.

[Sakuya]

Ooooh. Thanks!

[aggies11]

DVD video "minutes" are different than the minutes you find on CD audio discs.

In CD's 74minutes = 650MB with no exceptions. Because the standard for CD audio is exact. You make it one way, and one way only.

With DVD's they are a bit more flexible. You can choose to reduce the quality, to extend the time. So if you look at some DVDR discs you see something like "2hrs - Super High Quality mode" "4hrs High Quality Mode" "6hrs medium quality" etc.

So DVD discs can contain a fixed amount of DATA (eg. 4.39GB). However the video itself can come at various Data Rates. Eg 9Mb/sec 8Mb/sec 4Mb/sec etc. The lower the data rate, the lower the quality, but the longer it takes to fill up the DVD. (Note: These numbers are just hypothetical examples. I'm not sure what the actual limitations are for DVD data streams)

At Max DVD quality, you get about 1hrs per single sided/layer disc, 2hrs for a dual layer disc.

Hope that helps

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[Sakuya]

Yeah, thanks! So in past experiences, what size was one of your AVI files encoded for DVD? Just curious...

[gll99]

Minutes are a more common reference with DVD recorders but we can use similar references with DVD burners. There is no hard and fast rule.
Many encoder software won't refer to minutes but have a best, normal etc. settings for DVD where best roughly translates to a 4.7 gig disc holding a 2 hour movie. Many encoders let you adjust the bitrate within certain limits so you can decide how far you want to go according to your quality versus size criteria. If you convert a 2 hour avi at a default best DVD setting expect it to fill the disc. If you have a 3 hour movie that you want to fit on a DVD then you will need to reduce the bitrate to make it fit.

[Sakuya]

Do subtitles and still menus take up space too? I still haven't found a good program for making still menus AND selectable subs. Thanks for the help!

[aggies11]

Yep, Subtitles and Menu's take up a non trivial amount of space.

Take a look at the files in one of your *commercial* DVD's video_ts folder. Look for one called vts_01_0.vob. It's typically all menu's. Check out it's size.

I don't do much DVD authoring. Mostly because I *hate* spending all that time encoding. Anything that requires 100% of my cpu for several hours is something I do not look forward too.

Aggies