The 12.04 source 1 iso is too large to burn to dvd

what is the size of iso file?

kindly ignore last comment about iso file size question.

Did you MD5 test the ISO you downloaded?

No, I downloaded it from the website onto a windows 7 machine and attempted to burn the image to a dvd, it said the file was too large. I also downloaded it from the website onto the 12.04 LTS machine and used brasero. It produced a similar error about the file size being too large.

Then how do you know the file is complete and consistent?
https://help.ubuntu.com/community/HowToMD5SUM/

the md5 sums match

The file size is 4,809,152,512.

The path is ...

http://mirror.anl.gov/pub/ubuntu-iso/DVDs/ubuntu/12.04/release/source/ubuntu-12.04-src-1.iso

If it is DVD-5 then available Disc size is 4.7 .
I doubt DVD has not sufficient space,

maybe I can skip burn-to-dvd, and extract the data from the iso directly to the hard drive

Did you try burning the .iso file to DVD as a disk image (which should work), or did you try to add it as a normal file (which will fail)?
(see also https://help.ubuntu.com/community/BurningIsoHowto )

Why are you using the source ISO, if you simply want to install the OS you will want this:
http://cdimage.ubuntu.com/releases/12.04/release/ubuntu-12.04-dvd-i386.iso

Thanks, but I already have the os installed. I want the source so i can learn how to rebuild. I want to learn more about the kernel, drivers, etc. I'm trying to be helpful by pointing out there could be an issue with one of the iso files.

@ Manfred. Used disk image. Source iso 2 & 3 worked. It's only iso 1 that appears to be too large.

Then you can simply mount the ISO, no need to burn it at all.

sudo mkdir /media/iso; sudo mount -o loop ~/Downloads/ubuntu-12.04-src-1.iso /media/iso; nautilus /media/iso

Done.

Why are you burning it?

Thanks, that's useful information. I'll do that. I'm burning it because that's a common thing to do with iso. If they didn't intend people to burn dvd's from the iso files and simply mount them, why did they break the source up into 3 iso images?

Maybe its a tonne of data

It certainly is. I'm just trying to be helpful by pointing out that an iso is too big to burn to dvd. The other two are small enough, with the third only1G and change. Perhaps at some point the three could be rebalanced in case someone wants to or needs to burn dvds.

Thanks all