Burning DVD's longer than 120 minutes

[jnocon]

Newbie question:

I am using dvdbackup and dvd2oneX

No problems with movies less than 120 min - how do i get a movie of 150 min on a 120 min DVD?

jjn

[bugster]

Newbie question:

I am using dvdbackup and dvd2oneX

No problems with movies less than 120 min - how do i get a movie of 150 min on a 120 min DVD?

jjn

There is no such thing as a 120Min DVDr, they have a capacity of 4.37Gbytes. To fit a longer movie, use more compression, i.e lower bitrates. Results in lower quality though.

[galactica]

correct!

actually thats the beauty of dvd2onex because it could care less about the length. its only thought is final size.

if you have a 3 hour movie set to 4444mb it will be that size no matter its length

same with only a 2 hour movie set to 4444mb

the difference is QUALITY! a 3 hour movie will not be as good quality as a 2 hour movie (the loss is nothing major)

but you can increase quality of long movies by
1. doing movie only
2. using the fixed ie RATIO: CONTSTANT setting

hope that makes since.

[AntnyMD]

There is no such thing as a 120Min DVDr, they have a capacity of 4.37Gbytes. To fit a longer movie, use more compression, i.e lower bitrates. Results in lower quality though.

Some brands, notably TDK and Memorex, market their blank DVD media by running time as well as gigabytes(120min/4.7gb). Its the same way blank CD media labels read 80min/700mb.

[WiseWeasel]

That time spec is to be ignored, though, because MPEG2 is usually VBR, as opposed to CDDA, which is at a constant bitrate, making it possible to say how much playtime you can fit in a certain space. With DVDs though, that value is completely meaningless, since the bitrate is not constant.

[AntnyMD]

The minutes indication shouldn't be ignored, because it is obviously meaningful to a certain subset of people into making their own DVDs. If it didn't give any indication of how much material one could expect to fit on a disc, the 4.7gb number becomes even more meaningless. We all know, in fact, that DVD's actually hold 4.3gb ±.1gb of data.

I've found through my trial and error that most commercial DVD's have a variable bitrate between 3mbps and 9mbps, with a consistent average of around 4.5mbps, yielding movie-only of roughly 4.4gb for a 2 hour movie. When I capture my MPEG2 material off television at a constant bitrate of 4mbps, I get ... guess what ... 120 minutes per disc.

[WiseWeasel]

Actually, at 4 Mbps, you can fit 149 minutes of pure video (((4.37GB)*(1024 MB/GB))/((4 Mbps)/(8b/B)))/(60 sec/min) = 149 minutes not counting audio track (minimal impact). But that's besides the point. MPEG2 can look good at DVD resolution at around 2-2.5 Mbps with the right source and encoder, yielding about 238 - 298 minutes. This is not counting the 128 bps AC3 audio track, but illustrates the highly variable amount of playtime you can fit in 4.377 GB (4700000000 bytes / 1024 bytes/kB / 1024 kB/MB / 1024 MB/GB). 120 minute DVD-R media can fit more than twice that, making that value pretty useless in my book. For audio CDs, on the other hand, the data is always at the standard CDDA bitrate, and so you can say exactly how much playtime you can fit in a certain space. For DVDs, however, this is ridiculous.

[geek rock]

as has been brought up before.. the "120 minutes" printed on DVD-R's is usually referring to a recording setting on the set-top DVD recorders.

of course this isn't said anywhere by the makers of the discs.. which leads us to all this confusion.

[AntnyMD]

People who love to whip out the MPEG Math™ always fail to acknowlege that those figures apply to the strictest constant bitrate ... which in itself is a misnomer ... CBR is more akin to "controlled" bit rate than anything else. And who makes a pure video DVD with no audio? A newbie?

[galactica]

I just love watching you two go back and forth

[WiseWeasel]

It wasn't a real-world situation, but merely a demontration that you can fit wildly varying amounts of playtime on a DVD depending on how you encode the video (and audio). For most people, 120 minutes is not an accurate representation of how much you can fit on a DVD. With DVDSP 1.x, lots of Mac users were encoding MPEG 2 at a CBR, and due to the encoder's limitations, live action video didn't look good below a certain bitrate (around 4-4.5 Mbps). Now, with DVDSP 2.x out, and a much better encoder capable of VBR encoding, multiple passes and many filters, they'll find they can fit a lot more playtime on the same DVD media. Since with good VBR encoding, the final output bitrate will depend largely on the source material (cartoons will use up a lot less bandwidth than the latest action movie), it is ridiculous to say you can fit a certain amount of playtime on a DVD-R. I agree this might be useful with set-top DVD recorders that record at a certain constant bit rate, but in that case, it is an exercise for the set-top recorder manufacturers to determine how much playtime their customers can fit at specific quality settings. The DVD-R media producers can have no way of knowing how the MPEG2 and various supported audio formats are going to be encoded, and so it is silly for them to try to advertise a certain playtime. All I'm saying is there is no such thing as a 120 minute DVD-R disc, but there certainly are 120 minute encoding setups for 4.7 GB DVD-R media. Whether or not these setups are common, or relevant to you is completely subjective. For people using iDVD, for example, their 4.7 GB media is 90 minutes worth of playtime.