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What is it?
As optical media is encoded digitally, all data is recorded in a binary on/off or 0 and 1 state. Post Gap is essentially a gap of digital nothingness at the end of the data on a CD ROM. It is 150 sectors of all zeros which equates to about 2 mins of audio silence at the end of the data.
Why is it important?
It is important because Philips, who invented the CD, say it must be there for it to play correctly. Philips set out their specifications for optical media in what are called "Colour Books" Each book has a different colour cover for each type of CD. For example the Red Book specification relates to CD audio.
With these specifications in place manufacturers are able to make CD playback devices that are able to read the data on the disc. If a disc differs from the set specifications, CD playback devices can have difficultly in retrieving the data.
What happens if it is missing?
As the CD device is approaching the end of the data it will look for the Post Gap. If it is not there the CD device will have to make a decision as to whether the last 150 sectors of data should or should not be there. This will cause instability in playback in mass produced discs.
What caused it to be left out of the burn?
The software that you used to burn the CD with caused the fault. The burning software is what tells the burning drive what to write and what not to write. Most software that comes free, bundled with CD drives is not suitable for creating publishable materials. This type of software is for domestic use. The focus here is on "bells and whistles" and nice interfaces, not necessarily mastering a colour book specification disc to be distributed to market.
What software should I use?
We recommend Gear Software.
Gear software produces a range of professional burning software that will burn a post gap.
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