What is the 120 minutes DVD length based on ?

[davexnet]

4.7 GB blank DVD's usually have 120 minutes printed somewhere on the container.

With CD's @ 74 & 80 minutes, this refers to the exact recording time of an audio (redbook) CD that
will fit.

With DVD, what does the 120 minutes refer to?

[manono]

With DVD, what does the 120 minutes refer to?

As far as I know, nothing. You can put just about as many minutes on a DVDR as you like although, of course, at low bitrates the video might not look so good.

[redwudz]

Actually, nothing at all. You can put eight or more hours on a DVD. But generally, two hours or less video on a DVD-5 will give you good quality. The bitrate used is much more important than the playing time.

[davexnet]

That's what seems curious to me. As you mentioned, I (and just about everybody) have been making DVD's
with less or more time depending on how we chose to encode them.

That the 120 minutes means nothing, and that it serves to confuse newbies,
seems odd. That's why I thought that there may have been a more precise, albeit obscure, meaning to it.

[DB83]

I thought it was a reference to the SP mode on a recorder which invariably gives you just over 120 minutes on a disk.

[guns1inger]

I thought it was a reference to the SP mode on a recorder which invariably gives you just over 120 minutes on a disk.

Not sure which came first, but 120 minutes has come to represent SP type quality. That said, it is still an arbitrary number based on a reasonable average bitrate/quality trade off. I wonder if they would have caused more or less confusion by not putting a running time on blanks at all.

[jagabo]

It's based on the assumption of ~4500 kbps encoding.

[dphirschler]

I think coming up with (and promoting) 120 mins and "SP" quality is a good thing. Average consumers don't want to think much more than that. Of course we "experts" know we can fit more on a DVD but we know what we are doing. Average consumers using CBR really don't need any more settings than HQ, SP, and the other lower settings. That's what the PC (and VBR) is for, right?


Darryl