Phil Leigh;261499 Wrote: > I'd go out on a limb and say that this problem is now materially solved > when using something like EAC or similar which will "try try and > try again" to get the bits off... > > I suppose you could argue that AccurateRip doesn't prove we are getting > the right bits, only the same bits...but this seems a very unlikely > outcome to me. I agree the problem is solved by a combination of EAC and better drive design. Not only do AccurateRip checksums match, but I see many telltale signatures that give me confidence that ripping is accurate. One such signature is the HDCD psuedo-random bitstream. Programs, such as hdcd.exe look for this sequence, and while it is repeated several times when it occurs and periodically throughout the disc, it will not be detected if the bitstream is not substantially bit-correct.
On mono CD tracks, I try to collapse them down to a mono WAV file before encoding. While I've never seen a mono CD with numerically identical tracks, I've seen: 1. Mono CDs where the audio is numerically identical except for the low-level dither. While collapsing this to mono doesn't offer any audible advantage, it does save FLAC from having to encode the random dither difference. 2. Mono CDs encoded from a mono analog source with a stereo ADC. This is quite common. Ususally results in a low level difference due to the inevitable channel imbalance. 3. Mono CDs where the mono source tape was played on a stereo tape machine through a stereo endcoding chain. Also surprisingly common. Differencing the channels usually highlights azimuth errors and tracking errors as well as oxide shedding, folds and other tape flaws. 4. Mono CDs where stereo reverb was added to a mono source. For (1), (2) and (3), I usually just try to pick the best channel and use it for encoding the mono FLAC, for (4), often summing the channels gets rid or most or all of the reverb. Anyway, particularly mono CDs where the channels are numerically identical except the dither give me confidence in the ripping process. Every once in a while I have seen such a CD where there are occasional mismatching samples. Interstingly enough, I get identical mismatching samples ripping on different drives and AccurateRip says that the rip is good. I can only speculate that maybe this is the result of the 1630 conceiling an error when the U-Matic tape was played back to cut the glass master, so such an error is embedded in the CD itself. -- Timothy Stockman ------------------------------------------------------------------------ Timothy Stockman's Profile: http://forums.slimdevices.com/member.php?userid=8867 View this thread: http://forums.slimdevices.com/showthread.php?t=42435 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
