Google Answers Logo
View Question
Q: Multi-session overhead: How much space do I lose for each session (DVD&CD) ( Answered 5 out of 5 stars,   0 Comments )
Subject: Multi-session overhead: How much space do I lose for each session (DVD&CD)
Category: Computers
Asked by: donphiltrodt-ga
List Price: $7.00
Posted: 22 Jan 2004 19:33 PST
Expires: 21 Feb 2004 19:33 PST
Question ID: 299164
Burning a single-session disc-ot-once is more storage-efficient than
burning multiple sessions.  But how much?

My question: How much space do I spend on "overhead" when I burn multi
sessions on a DVD-R?  (same question for a CD)  What does each session
cost me, in terms of available storage space.
Subject: Re: Multi-session overhead: How much space do I lose for each session (DVD&CD)
Answered By: haversian-ga on 22 Jan 2004 21:44 PST
Rated:5 out of 5 stars
Good evening donphiltrodt-ga,

I'll answer the CD question first, as it's the first one I found the answer for.

According to the CDRW FAQ, the first session on a CD costs 28MB (and
will work on all CD drives).  Subsequent sessions cost 13M each, and
will only be visible on multissesion drives (pretty much anything

According to page 20 of "Technical Introduction to DVD+RW/+R", DVD
session overhead is 4MB, and DVDs support a maximum of 191 sessions. 
Again, the first session works for all drives, but only multisession
DVD drives can access subsequent sessions.


   Technical Introduction to DVD+RW/+R
   FAQ about CDR and CDRW disks

Request for Answer Clarification by donphiltrodt-ga on 22 Jan 2004 22:57 PST

DVD-R and DVD+R are different formats, and (AFAIK) there's no
technical reason that the session overhead would be the same.  And
since I requested info on DVD-Rs, please confirm the session overhead
for the "DVD-R" format.

Yeah, I know, it doesn't seem like that big of deal.  But I'd just
rather not assume anything.  Knowing is more fun than assuming.  :-)

Thank you for understanding.

Clarification of Answer by haversian-ga on 23 Jan 2004 06:58 PST
No, you're quite right - I misread either your - or their +.  I should
be the one apologizing.  As it happens, I saved myself a lot of
trouble with that misread: DVD-R info's a lot harder to come by.  A
quick search has turned nothing up, but I thought I'd let you know I
got your clarification and will work on it some more after class.

Offhand, I think they would be the same, as long as they're both
formatted using UDF, but I ought to be able to find something more
authoritative than a hunch for you.


Clarification of Answer by haversian-ga on 23 Jan 2004 13:56 PST

Alright, I finally found it.

I had to (horrors!) use Altavista to do it, though.

CDFreaks, who sound like they'd know, have the info you're asking for,
which they've buried at

Basically, the way it breaks down is that a DVD has a lead-in and a
lead-out which together pad the actual data on the disc.  Different
sessions have a border-in and a border-out, except for the first
session which omits the border-in as the lead-in for the disc is
sufficient.  The info I'm getting says 32-96MB for the first border
(which would be the first session's border-out), and 6-18MB for
subsequent borders.  Towards the end of the linked article there's a
diagram which is a bit more clear about where all these sections
actually go.

I'm going to keep looking to try to find out why the 3x difference
between minimum and maximum for both border sections - there's
probably a good reason the ratio is the same for both.  Unless you're
specifically interested in that, I'll give up after a bit; otherwise
let me know and I'll press onward.


Clarification of Answer by haversian-ga on 24 Jan 2004 08:30 PST
Good morning donphiltrodt,

That was very generous of you; thanks!

As you may have guessed, I'm a bit of a computer geek.  I've got
Windows (XP), Linux (RedHat), MacOS (Classic, alas), and BSD (openBSD)
machines running, and with the exception of the BSD machine I'm
reasonably knowledgeable about them.  I'm also somewhat of a hardware
geek, though I don't know much that's specific to Mac hardware.  I
read a lot, and speak Spanish, which help out in sometimes-unexpected

I don't want to buttonhole myself into answering only tech questions,
though if you look at my past questions, you'll see I tend to do that
myself because they're usually the easiest.  If someone's asking for a
simple lookup of data, I may or may not answer; it's the puzzles that
interest me more.  Though questions whose answer I'm interested in as
well are more likely to attract my attention - after all, what's
better than being paid to figure out something you'd like to know

That mostly answers your question, I think...

donphiltrodt-ga rated this answer:5 out of 5 stars and gave an additional tip of: $3.00
I appreciate your tenacity.  Please respond with your areas of
expertise or interest so I can address questions to you specifically
in the future.

There are no comments at this time.

Important Disclaimer: Answers and comments provided on Google Answers are general information, and are not intended to substitute for informed professional medical, psychiatric, psychological, tax, legal, investment, accounting, or other professional advice. Google does not endorse, and expressly disclaims liability for any product, manufacturer, distributor, service or service provider mentioned or any opinion expressed in answers or comments. Please read carefully the Google Answers Terms of Service.

If you feel that you have found inappropriate content, please let us know by emailing us at with the question ID listed above. Thank you.
Search Google Answers for
Google Answers  

Google Home - Answers FAQ - Terms of Service - Privacy Policy