Blank DVD goes from 4.38 GB to 4.08 GB

Jeff S
Jeff S used Ask the Experts™
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I am trying to burn a movie, yes its my DVD and not copyright protected. When I put my DVD into my machine, it reads as 4.38 GB, my file is 4.35 GB - so i think I am good to go. After wasting 4 DVDs its erroring out saying I need more room. So ... I just placed a blank DVD in .. after 2 or 3 minutes it fills up with 313mb of info. What gives?
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Commented:
There could be a number of reasons for this:

1) The OS measures a GB via 2^30 bytes, but generally DVDs (and some programs) count GB as 1,000,000,000 bytes. This leads to these types of discrepancies.

2) There is formatting involved in the making of a disk, which takes up space.

3) Also, when making a DVD that you plan to put in a DVD player, you need to create a video DVD. It sounds like you are making a data disk with a 4.35GB file on it. This would not work in a dvd player.
Commented:
when a dvd is about to be burned on, it prepares the disk. in other words, it formats and writes a sort of file allocation table to it and this takes space.

another thing is that these dvds are never accurate in what the project to be.

try reducing / compressing your video or getting a higher capacity dvd if possible.
The File Allocation Table on a dvd is surprisingly large, especially if you are creating a video DVD rather than a files filled DVD.  That is the likely cause of the disc appearing too small.  You can correct it by removing a few files/recompressing but I think you would be better off buying a few double layer discs and using those (assuming your DVD burner can cope with them which almost all newer models do).
Retired
Most Valuable Expert 2013
Top Expert 2009
Commented:
This has nothing to do with file allocation tables;  different measurements (the 4.38GB indicated as free space is indeed 4.38GB in "computerese" (1GB = 1024x1024x1024).    In "disc-drive-maker-ese" it would be 4.7GB;  nor any extra formatting for a standard DVD.

The stated capacity of a DVD INCLUDES the normal overhead associated with lead-in and lead-out for the DVDs  ==> i.e. you can absolutely write 4.38GB of data to the disc.

What is almost certainly happening in your case if that you have a packet-writing utility installed, which treats the DVD like a large floppy ==> THESE indeed "format" the discs when a blank is installed, and this will reduce the capacity somewhat.    Packet writers have the advantage that you can write multiple times without using multiple sessions (which DO add overhead in the form of additional lead-in and lead-out data).    Nero's InCD;  Roxio's DirectCD; etc. are common examples of these.   Windows 7's built-in DVD writing capability also allows you to select a packet-writing format for DVDs (if you select to treat them "... like a USB flash drive ...".

Simply disable your packet-writing software and you'll be able to write a standard DVD with 4.38GB of data.   [Or if you're using Windows 7's built-in writing feature select the 2nd option ("With a CD/DVD player")].

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