本帖最后由 dengxiaochu 于 2019-12-2 19:51 编辑 |
Error recovery quality
(Default: Medium, Recommended: Low)
When an error is detected after reading a frame, EAC re-reads the frame 16 times in an attempt to get at least 8 identical results. The error recovery quality setting determines the maximum number of times EAC will do the 16 re-reads:
Low = one batch of 16 re-reads
Medium = up to three batches of 16 re-reads (16, 32, or 48, total)
High = up to five batches of 16 re-reads (16, 32, 48, 64, or 80, total)
For each batch of 16 re-reads, there's a row of red error correction "lights" in the extraction status window. If no batch of 16 re-reads produced 8 identical results, EAC considers whatever data it got to be "suspicious" rather than correct. EAC continues reading the entire batch of 16, even if it has already obtained 8 identical reads.
Setting this option to medium or high may or may not result in a reduction of errant data in the event that re-read sets are required. Unfortunately, errors can occur with consistency and as such, more aggressive settings can result in errant data going unreported as being suspicious. While medium may be of some benefit to lightly damaged discs, high generally leads to diminishing returns. A section of audio that can't be ripped correctly through three sets of re-reads is likely not going to be ripped correctly after two additional sets. It is also unlikely that the two additional re-read sets offered by the high setting will deliver an audibly superior result. Furthermore, ignoring the additional ripping time required before EAC finishes, forcing the drive to perform additional re-read sets increases wear. However, because EAC chooses the most consistent data over all the re-reads performed in the event that 8 identical results aren't found in any given re-read set, increasing the total number of re-reads might be of some benefit (provided that the most consistent data also happens to be error-free). It is recommended that high be reserved for use in the event that an accurate result can't be obtained otherwise. Correction through the CUETools database is a far more effective way to handle ripping errors than EAC's archaic method of using re-read sets which has never really worked that well on the whole.
Drive caches audio data
In order for secure mode to work properly, every read request made by EAC must cause the drive to seek data from the CD. If your drive caches audio, subsequent requests for the same data may result in the drive only fetching this data from its buffer, rather than from the physical disc. To prevent this from happening, EAC has a routine to ensure previously requested data gets flushed from drive's cache. This is done by having the drive read extra data from the disc—more data than the cache can store.
If the "Detect Read Features..." function reports "Caching : Yes", it is important that you enable the cache flushing routine by checking the "Drive caches audio data" box.
If the "Detect Read Features..." function reports "Caching : No", it is not necessary to enable the flushing routine. Checking the "Drive caches audio data" box with drives that are reported by EAC as not caching will not improve EAC's accuracy. It won't improve EAC's ability to detect errors nor EAC's ability to correct them. What it will do however, is reduce your ripping speed and shorten the life of your drive.
Tip #1: If you're concerned that your drive caches audio data even though EAC is saying otherwise, try ripping a scratched disc (one known to produce errors easily). Make sure you uncheck the "Drive caches audio data" setting AND uncheck the "Drive is capable of retrieving C2 error information" setting. Make sure you also set the error recovery quality to "Low" (this setting can be found under the Extraction tab in the EAC Options dialog). If EAC is capable of displaying a read error then cache flushing isn't necessary. Ignore any sync errors that may be displayed; they are irrelevant to this test.
Tip #2: Tip #1 is all you need to know, but if you're still paranoid that your drive caches audio, feel free to try Feurio's audio caching test (Ctrl+Alt+P\Test device\Cache test) or spath's cache explorer. If either determine that your drive doesn't cache or caches less than 64 KB of data, then cache flushing isn't necessary (ignore the reported buffer size when using cache explorer). The reason for the 64 KB barrier is that EAC will never request less than this amount while ripping (link).
Note: If "Drive has 'Accurate Stream' feature" is deselected, then "Drive caches audio data" is automatically checked, regardless of whether the drive actually caches audio data.