This tale must begin with a bit of CD recording history. Another aspect of the tale told under Remembering History in this primer is the effect of writer tolerances on some of the features and limitations of modern recording.
One part of the specification not addressed here is the requirement for a two-second (150-block) gap before the first track of any CD-R. Instead, we're looking at the space between two tracks, particularly (at first) on an audio disc. Why are those two seconds "wasted"? Simply because the tracks are written one at a time.
When CD-R was being defined, the problem of positioning the laser was severe. It was simply not possible to tell the laser to go to a specific point and to expect it to find that point on the inscribed wavering spiral. That's still true, but the uncertainty in positioning and the amount of information needed to get synchronization is much less with modern production techniques than it was twenty or so years ago.
The original mode of writing audio was Track At Once - TAO. A track would be written, the laser would turn off, the next track would be prepared, the write would be readied by servoing the laser to the point where the write was to begin, the laser turned on and the next track was written. To be sure that the track would begin as intended, the space from its predecessor was set to 150 blocks.
Then Disc At Once was added to the capability. In DAO, the TOC is written first to indicate where each track is to be regarded as starting. Then the laser turns on and burns all the data as a single track with no interruption where the tracks are separated and no required gap. Note that some players have more trouble finding the start of an interior track on a DAO disc than they do with TAO - the reader would like that gap for synchronization and on a disc which it does not read easily it may have to seek. That's particularly true for older audio players, but it can happen even with a new one with a poorly matched medium.
Someone then realized that a gap might still be desirable between some tracks in DAO, so an adjustable "gap" was introduced; it's not really a gap, but a specified period of silence introduced before the next track starts. Some software will also allow you to adjust the intertrack gap when writing TAO, which is useful for drives which don't support DAO, but is both imperfect (there is always a gap) and in violation of the specification.
So, what does this have to do with Sanyo's "burn proof" recording, since licensed by other manufacturers? First "burn proof" does not mean protected against all failures (and certainly not protecting a blank from being burned - recorded - at all). It is a means of reducing the effect of buffer underrun. If the flow of data to a recorder is interrupted long enough to empty the buffer, the recorder reports the last full block written and the software holds off until the buffer reloads. Then it begins to write from the end of the last block to complete the track. The process works because manufacturing tolerances have been improved so much that the gap between the end of one block and the start of the next can be less than the space needed for the reader to recognize a break. There is still a gap, the laser does stop writing, but it is not recognizable because the specification allowed for an even longer one to be ignored.
Back when buffer underruns were common, "burn proof" would have been a boon. Today, an underrun is rare and indicates a serious problem in system configuration which should be addressed, not simply patched over. In a sense, it may be unwise to use the "burn proof" feature because it keeps you from knowing you have a problem to fix. Of course, when the feature saves you a disc, you will feel differently.
E-mail me at cdrecording@mrichter.com
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