What is Jitter?
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Loading ...Jitter occurs with digital audio extraction (ripping) or when digital audio is converted to analog. For example on a CD (DVD) the music data is written in a single, spiral-shaped track. Thus the data is given as a long chain of bits that ideally can be read continuously. On HDD the data is divided into sectors.
On Audio CDs or DVDs the logical sector structure is missing. There is only a time-code , that is coded into the data that indicates the position with a resolution of 1/75 seconds. (This time code is also used for the information on the display of the CD-player).
If the computer now wants to read a certain position of an Audio CD (DVD), the CD-ROM (DVD-ROM) can not locate the position precisely (i.e. only accurate to within 1/75 of a second) because of the missing sector marks.
Normally this isn’t a problem because when reading out you usually start at the beginning of a track; the start of a track consists of silence anyway. In the course of reading on, the CD-ROM (DVD-ROM) simply follows the track and transfers the data to the computer.
This problem, wich is called a jitter error, will only occur the moment the computer can not take up the data quickly enough and thus the CD-ROM (DVD-ROM) has to start up again. (As the CD continues to spin in the drive, the reading head initially “loses” the track and has to look for it again and then has to restart the read operation).
Because it is not possible to locate the exact position again (using a time code) at which the read operation stopped, some samples are skipped or read again on the “restart” of the read operation.
The Jitter Correction restore the audio to its original condition.
Tags: CD, correction, dvd, error, jitterRelated posts
Tags: CD, correction, dvd, error, jitter