User:Mjb/CD ripping
Contents
Exact Audio Copy
Timing problem
An EAC burst rip will say "Timing problem" if a read command took an unusually long time, possibly because the drive was losing sync or was trying to fix a read error. The data may be fine. This is in the FAQ.
Pre-emphasis
Pre-emphasis flags are only read from the TOC, where they are quite often going to say "No" when the subcode correctly says "Yes". There were a few EAC "0.95 prebeta" versions which could read the flags from subcode as part of "manual TOC detection", but this feature was removed because it could somehow also be used to circumvent copy protection.
CUERipper
Copy OK
The EAC-style log says "Copy OK" on all tracks, regardless of what happened during the rip. Discussion: http://www.hydrogenaud.io/forums/index.php?showtopic=104498
Pre-emphasis
On the CD The Digital Domain, the first 17 tracks have pre-emphasis, as do tracks 22 and 24. I confirmed that the disc has correct subcode flags set by checking the analog output for these tracks in a real CD player; they play with the proper attenuation. However, CUERipper adds FLAGS PRE in the cue sheet for tracks 21 and 23 as well. So it seems CUERipper can make mistakes when reading these flags.
S/PDIF capture
My real CD player has a digital S/PDIF output. This is probably 20-bit, 44.1 kHz output, with the bottom 4 bits of each word set to zeros (since the CD only has 16-bit data).
Unfortunately, I have to use an old AudioAdvantage Roadie USB soundcard to capture it, and it is a piece of junk. I have trouble getting a setup that doesn't add noise, resampling artifacts, or HF rolloff.
I got a slight level boost and added broadband noise when I captured through the MME interface. So instead, after much trial and error, I got it to work if I use:
- ASIO4ALL, with the advanced options set so all the checkboxes are off
- in Windows, set recording device to the Roadie SPDIF input, and under advanced set it to 16-bit, 44100 Hz
- select ASIO4ALL and 44100 Hz from the hardware prefs in Audition
- record at 16-bit 44100 Hz in Audition
Naturally, I have to trim the ends and make sure it's aligned if I want to compare this to a DAE rip.
Close but not perfect
The S/PDIF capture is very close to the DAE rip, producing an identical waveform, but it is not bit-identical: everything is offset by roughly half a sample! So each sample's amplitude is quite different from the originals, even though the resulting waveform is the same. It is as if the waveform was converted to analog and then digitized again a split-second later.
The offset can change from capture to capture, but on 2 of 3 captures it ended up being exactly the same amount. I am unsure what to make of this. Does it happen in the conversion of the decoded CD data to the S/PDIF signal? Does it happen in the soundcard? The audio software?
Pre-emphasis
Pre-emphasis is not applied when I do S/PDIF capture. The data stream does include a pre-emphasis flag, but if it is being set, it is being ignored by the soundcard. This may be by design, as it is just trying to pass the data through.
