Cd Error Correction C1 C2
Hi-Res Audio Testimonials Bob's Bio ISRC Codes FAQ Copyright Info Clients Site Map Contact Us digital Errors And cd Quality By Bob Speer Write Errors Write errors can result in CD failure. CD manufacturers will reject a master disc if write errors exceed their specifications. There are three common errors types that affect CD quality. They are C1, C2, and CU. C1 Errors C1 Errors refer to the block error rate (BLER), which consists of bit errors at the lowest level. C1 errors are always expressed in errors per second. All CDs and CDRs contain C1 errors. They are a normal result of the write process. However, the maximum C1 error rate for a quality recording is an average of 220 errors per second based on 10 second samples. C2 Errors C2 Errors refer to bytes in a frame (24 bytes per frame, 98 frames per block) and is an indication of a CD player's attempt to use error correction to recover lost data. C2 errors can be serious. In theory, a CD player should correct them. C2 errors are usually an indication of poor media quality, or the failure of a CD burner to produce a quality burn (see conclusion). CU Errors CU Errors refer to uncorrectable errors that are present after error correction. No CU errors are allowed in a recorded disc. Generally, discs with CU errors will not play properly because they contain data that cannot be recovered. When errors are the result of physical damage to the disc, CIRC Logic - Cross Interleaved Reed-Solomon Code, is used to identify and correct random errors, which allows some damaged CDs to play without any distinguishable difference. Conclusion CD replicators consider a disc with an average of 220 C1 errors per second, "a good quality disc." Typically, our masters average less than 1 C1 error per second with absolutely no C2 or CU errors. We have our own standard which states that in addition to no C2 or CU errors, we will not ship any disc that averages more than 2 C1 errors per second. That's .009% of the maximum allowed for a good quality disc. This provides you with an excellent master of the highest quality. If you're going to have your CD professionally replicated, there is no substitute for a quality master provided by a professional mastering facility. While mastering is about EQ, dyna
Me? Password Register FAQ Community Today's Posts Search Community Links Social Groups Search Forums Show Threads Show Posts Advanced Search Go to Page... Page 1 of 2 1 2 > Thread Tools 19-09-2003 #1 rdgrimes Retired Moderator Join Date: Jun 2002 Location: Deadwood Posts: 11,533 Interpreting error scans: This thread is for discussion of C1/C2 error scans and how to interpret them. Please begin by reading the media FAQ to get the basics on errors and general media info. There are several testing utilities around that measure either C2 or both C1 and C2. for this discussion we are http://www.cdmasteringservices.com/digitalerrors.htm using Kprobe, which is designed to work with LiteOn burners. If you have a different burner or reading drive that reports errors in another program, by all means use it. The principles are the same. Please note however than scanning discs in a different drive than they were burned on will introduce additional nuances into the scan results. When using that method, you should give less weight to the actual error counts http://club.myce.com/f77/interpreting-c1-c2-error-scans-75573/ and focus instead only on the differences between scans. The point of scanning is to find the combination of media and burn speed that produces the lowest error rates on your burner Each scan that's done for the purposes of comparison should include only one change in the variables. In other words, don't change both the media and the burn speed, don't change both the burn speed and the read speed, change only one thing and scan again to compare results. The point is to get burns with the lowest possible error counts. The actual error counts are not very important in and of themselves, and comparisons of scans done in different drives is NOT a good idea. The one and only hard rule with error scans is: less is better. If you lower your burn speed and you get a scan with lower error rates, you are moving in the right direction. If one media has lower counts than another, use that media. For our purposes, it doesn't make a lot of difference what is being reported as "C1" and "C2" by the drive and the software. All we really need to know is that C1 is the "friendly" error and C2 is the nasty error. All discs show C1 on them in varying amoun
The terminology used in CD ripping is particularly confusing as there appears to be a lack of consistency (and in some cases, accuracy) between the various software providers and user forums on the Internet. This document is an attempt to clarify some of these terms and http://docs.linn.co.uk/wiki/index.php/CD_Ripping_Terminology show how they relate to the fidelity of ripped audio. Contents 1 Jitter 1.1 EFM http://www.cdrinfo.com/Sections/Reviews/Specific.aspx?ArticleId=7378 Jitter 1.2 Sampling Jitter 1.3 Read Offset Jitter 2 Error Correction 2.1 Is the CIRC error detection/correction process perfect? 2.2 What happens if an uncorrectable error is encountered? 3 Recommendations for achieving accurate rips Jitter Jitter can have many meanings in digital audio but it generally refers to a timing error of some sort. Some forms of jitter can have a considerable effect cd error on audio quality, others are benign as long as they are below a certain level. It is worth describing three forms of jitter so that the differences between them can be seen: 1. EFM Jitter 2.Sampling Jitter 3.Read Offset Jitter EFM Jitter EFM (Eight-to-Fourteen Modulation) is the final part of the encoding scheme used to produce the spiral of microscopic bumps on a CD. When a CD player reads this spiral pattern, bumps will be interpreted as one logic cd error correction level (e.g. ‘1’) and the spaces between the bumps as another (e.g. ‘0’). This stream of 1’s and 0’s is called the EFM signal and in an ideal case it should be identical to the original signal used to record the disc. Unfortunately, because the CD mastering and replication processes are not perfect, errors occur in the shape and position of the bumps. These physical errors translate into timing errors in the recovered EFM signal and this is what is termed EFM Jitter. Because EFM jitter is always present, the CD reading process is designed to be immune to it – up to a point. The EFM data stream is ‘self-clocking’, meaning that the original timing of individual ones and zeros can be recovered using a phase-locked loop (PLL). The PLL generates a bit clock that locks on to the EFM signal such that, on average, the edges of both signals coincide. The EFM signal is then re-sampled using this clock and the resulting data fed into an elastic buffer. A second fixed-frequency clock controls the rate at which data exits this elastic buffer and the disc speed is controlled to keep the average buffer occupancy at 50%. This 2-stage re-timing process completely decouples the output (i.e. audio) clock from the jittery EFM signal. Excessive high-frequency EFM jitter levels may result in bit errors (e.g. a ‘1’ being read as a ‘0’), but these c
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