Safe audio CD ripping technology is reading audio CD tracks with improved steadiness to errors that can appear by different reasons.
In the article "safety" mean "steadiness to error reading".
"Unsafe" rippers may have next kinds of behavior:
1. Read without error reporting, and/or
2. Rip with error first time. For repeat CD ripping without ejecting: successfully read without error report, but with errors in audio data.
3. Don’t try recovery audio data.
In general, safe ripping technology is:
1. Re-reading CD's audio data fragments
2. Reading error markers (C2)
3. Processing data obtained in points 1. and 2.
Result of the processing is detected and/or probably fixed error.
Some CD rippers provide this algorithm. Including open source.
Result can depend on implementation the algorithm.
Each byte of raw audio stream under control.
3. Re-reading several times for each fragment of CD's audio data
Re-reading may cause different result of reading due optical-mechanical factors.
Also accounted sutuation when CD reading devices may always use builtin cache.
AuI ConverteR provide special way of reading that try pass by such kind of cache.
4. Complex statistical processing full volume of information extracted from CD
It allow detect errors and try to restore original information.
As result AuI ConverteR show results of ripping:
- Fatal errors number (what it can't restore)
- Probably restored bytes number
This algorithm currently work under Mac OS X.
Under Windows AuI ConverteR currently use external utility designed for work with damaged CDs.
We planned to replace current CD ripper under Windows.
We suppose, what new algorithm (already released under Mac OS X) give us more possibilities for control under ripping and for releasing of new ideas what we have and continue research currently.
For testing used as manufactured by third party audio CDs as own produced test CDs with different degree of damaging.
Own produced test CDs have exactly known binary content. It give full control of CD ripping quality. Content of ripped lossless files (WAV, FLAC, AIFF) compare with original binary data.
Complex processing (multiple readed CD's raw binary audio data and error markers) allow to check audio binary data integrity and try to restore damaged content in autonomous mode.
Restoring possibility especially actual for rare CDs.