Amazing new Discovery (but how)

Posted by: garyi on 25 November 2004

Me and the better half got into quite a heated discussion on the weekend regarding burnt CDs.

Some work we had been doing in photoshop had been burnt to CD in toast on my mac.

Sheila bought a CD home from work which she claimed contained new data burnt at work, the self same CD as burnt at home.

Thing is these disks I have here are CDrs they are not CDrw.

Well anyways the disk she bought home only showed the original data that had been burnt on the mac, so rather smugly I exclaimed that I was correct a CDr was burn once only jobs a good'n etc etc.

Well she stormed back off to work to check the disk and shure enough as well as the data burnt at home on the mac was her data burnt back on to the same disk from work.

Tonight in experimental mode I burnt a single image to disk in 'session mode' in toast.

The disk burnt and then verified. and as usual asked if I wanted to eject the disk or mount it. I ejected then put the disk back in, as expected it mounted on the desktop with the single image.

I then put another picture into toast and clicked burn again.

And what do you know, it burnt that bloody image onto the disk no problem, apart from the startling and useful discovery it ultimately means I am wrong!

But what the hell is going on, I was always bought up to to believe that a CDr can only be committed to burn the once, once done that was your lot.

As I understood it the software burnt a track at the beginning of the CD to establish what CD it was, how much memory was used etc etc, how can this be abused, i.e presumably that first image was burnt and then the next 'session' must begin after the last one on the CD.

The mac picks it up as individual CDs, so I had two CDs mounted on the desktop, however it was unable to read further 'sessions' to disk done from a PC.

Confused? You better believe it.
Posted on: 25 November 2004 by sideshowbob
It's called "multisession". You can append to a CD-R until you finalise it, i.e., write a table of contents to it, at which point it's fixed in stone. CD writers can read unfinalised disks with no problem.

I don't use Toast, but my guess is you haven't set the option to finalise disks after burning.

-- Ian
Posted on: 25 November 2004 by Tim Danaher
Gary --

This is standard behaviour with Toast (or any Mac burning software). Burning a session locks that part of the disk, but the rest of the disk remains free for recording. You can keep burning sessions to a CD up the CD's maximum capacity. All sessions appear as separate mounted volumes.

You used to have to drag every session to the Trash to eject a CD (arseache) but I think with 10.3, dragging only one session will eject the disk.

Cheers,

Tim
_____________________________

Os nid Campagnolo yw hi, dyw hi ddim yn werth ei marcho...
Posted on: 26 November 2004 by Hawk
Ive not tried it at home on the mac, but my work pc will happily keep adding data to a CDR time and time again, it only spits its dummy out if you try and save the same file again, or open a file and try and save changes...

I seem to remeber my old pioneer CDR was the same, you could keep recording extra tracks to the CDR until you hit the finalise button at which point it became game over.. Trouble was that the CDR couldnt be played on another CD player until they had been finalised..
Posted on: 26 November 2004 by garyi
Thanks for the replies.

It would appear problems only really start when you try and add data to the same CD from different computers as in our case, but its great to know this facility is available.
Posted on: 26 November 2004 by Berlin Fritz
If you shop carefully yers can save a fortune, and re-invest the rest into beer vouchers, innit.

Fritz Von Youknowitmakessense Smile
Posted on: 26 November 2004 by NaimDropper
garyi-
Many CD authoring programs will support mulit-session use, but a CDR is write once. You can't erase anything you've put on there and each session also gobbles up a nice sized chunk of disk space as a header or TOC or something (can't remember what exactly).
CD-RW on the other hand allows erasing (selectable erasing with the right program) and multiple re-writing.
So, you weren't wrong about CDR.
David
Posted on: 26 November 2004 by Paul Hutchings
We are talking a few years back but I once had to send a CDR to Vogon and spend the best part of £1100 because the PC crashed mid-way through adding a session to a CD that held the sole copy of some very important data.

I might be biased from that one bad experience, but I wouldn't trust multisession with anything important, especially with CDRs costing 20p.

Paul
Posted on: 26 November 2004 by garyi
Cool thanks Paul, I will check through my important CDs, and check if I have actually finalised them lol.

Where's your bloody mac eh?

As usual I think Apple woefully underestimated demand.
Posted on: 26 November 2004 by Top Cat
quote:
As usual I think Apple woefully underestimated demand.
Better to under-estimate than over-estimate, of course - brimming order books are a good thing for any business...!!

John

PS. Paul: that sounds like a very expensive and hard-worn lesson. Hindsight is a cruel mistress...
Posted on: 27 November 2004 by MarkEJ
Gary;

If each session on the disk is burned using ISO9660 ("Mac & PC" in Toast-speak), then it doesn't matter which platform is used -- I think all sessions (volumes) on the CD-R will appear on all platforms. It's only when the session format is platform-specific that limits occur.

Using the Finder to burn a disk (Apple Disk Burning) will result in a "Mac & PC" finalised, single-session disk, always. Plus, it takes quite a bit longer than Toast.
Posted on: 27 November 2004 by John Sheridan
quote:

CD that held the sole copy of some very important data

surely if data is that important then you make sure you have more than one copy of it?
Posted on: 27 November 2004 by Paul Hutchings
quote:
Originally posted by John Sheridan:
quote:

CD that held the sole copy of some very important data

surely if data is that important then you make sure you have more than one copy of it?


Well yes, but it wasn't me.. I'm just the poor network/systems sod who gets called when someone else screws the pooch.

Seems to happen quite a bit at our place.. people entrust the one copy of their important data to their PCs hard drive rather than the servers that are sitting there getting backed up every night.. unfortunately I don't make the policies I just bitch about the lack of them Roll Eyes

garyi - it's sat at the Nuneaton TNT depot according to apecode.

I called TNT midweek as I'd heard of apple not passing on all the delivery info and sure enough they had my name and street but no house or company name and no phone number.. it's scheduled for delivery Monday but I might give them a bell now and see if it's collectable (edit - just called and it's locked on the van)

cheers,
Paul