WHich means a slight degradation of quality, even though mostly inaudible for one generation.Įverybody can do the test himself with a bitmeter. Red book audio cds are designed for real time streaming performance and less strict error requirements, so concealment (concealment is not bit transparent error correction!!!) is part of the reading process, re-reading a faulty section is not intended, contrary to data cds.įor Red Book CD-DA between correction and full out error there is the stage of concealment.
That's only true for data formats like cd-rom in mode 1 (yellow book), which DDP usually is written with. In which case the transfer from the source to the server at the plant is stopped and a new master is delivered. The only margin that matters is when the data is not completely recovered by the error-correction codes. This occurs when at least seven consecutive frames report a E21 or E31 error. The seventh version is known as a burst error. These are the ones from which there is no return. An E12 error is when C2 corrects one error in a frame, E22 is two corrections per frame, and E32 constitutes an uncorrectable error at the C2 level. When this occurs, it is handed off to the C2 level. E21 reports the rate at which two errors are corrected, and E31 is reported when C1 finds the frame to be uncorrectable. E11 reports the rate at which C1 detects and is able to correct one error per frame. You can have a low BLER, but if uncorrectable errors are contained, then the disc must be failed.Įrror report codes come in seven versions according to severity. It's not just the number of errors the type of error is paramount. In fact, most high-quality masters will measure considerably better than this, and many professionals prefer to cap the block error rate to 50 or less (you'll likely get examples here of teens or even single numbers).īLER, however does not tell the whole story.
Over several seconds, the average rate of all errors is taken, and industry practice dictates that if 3% or fewer of the data frames contain errors, which equates to a BLER of 220 per second or less, then the disc is suitable for use as a master. The most general measurement of CD errors is known as BLER. Larger errors are passed to the C2 level after an additional stage of de-interleaving. The first layer of correction is known as the C1. To elaborate, in addition to the audio and subcode information, there are eight CIRC parity bytes. Most plants will let it fly unless it results in an E32, the "CU" for uncorrectable. While technically a single C2 does not necessarily cause interpolation, you still should fail any disc intended as a master that has C2s, even correctable ones. Ah, so it's C2 errors that become interpolated, not CU?Nope - C2s can be correctable, but the error has to be bumped up to the second layer of error correction.
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