Jitter Correction
"Jitter" is a term used for the inherent uncertainty in most CD-ROM units, which is caused by the way audio is stored on a CD. Although one logical block on a CD takes up 2352 bytes, the amount of data stored in the block varies. For a data block, 2052 bytes are actual data, and the remaining 300 bytes are information used to find the block accurately. For audio, however, all 2352 bytes contain audio data - there is no positioning information returned in the block read. When CDs first came out, they were used for audio, and it didn't matter if a CD player got within +/- 1/75 of a second of the intended start position. After it started, as long as the player kept reading, it could accurately read the data - the problem only came about when initially seeking the start position.
"Jitter correction" is the process of trying to compensate for "jitter" in software. Generally, it involves using overlapping reads, and attempting to match the end of one read with the beginning of the next, so that there are no gaps in the data read. These gaps cause clicks and pops in the resulting WAV or MP3 file produced. For instance, the program may begin reading a track at block 1000 and read 27 blocks total. On the next read, it would issue a read command starting at 1024, and would try to match the end of the first read in the beginning of the second read. Once it finds a match, it would cut off the beginning of the second read, and use only the part after the match. In this way, you can eliminate the clicks and pops.
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