Difference between revisions of "User:Mjb/CD ripping"
(→S/PDIF capture) |
(→S/PDIF capture) |
||
| Line 27: | Line 27: | ||
I got a slight level boost and added broadband noise when I captured through the MME interface. So instead, I used ASIO4ALL to create an ASIO bridge, and configured it to not resample. In Audition, I set the input audio device to the ASIO4ALL version of the Roadie. | I got a slight level boost and added broadband noise when I captured through the MME interface. So instead, I used ASIO4ALL to create an ASIO bridge, and configured it to not resample. In Audition, I set the input audio device to the ASIO4ALL version of the Roadie. | ||
| − | Even with this (ASIO4ALL, 48 kHz rate), I still get some mirror-imaging above 22.05 kHz. It goes away after I use Audition to bring the sample rate back down to 44.1, | + | Even with this (ASIO4ALL, 48 kHz rate), I still get some mirror-imaging above 22.05 kHz, so there is still resampling happening. It goes away after I use Audition to bring the sample rate back down to 44.1. |
| + | |||
| + | Also, the high end rolls off above ~18 kHz, no matter what I do. It may be Audition's filters or it may be the Roadie, who knows. | ||
In the end, with the exception of that slight HF dip, I get amplitudes almost exactly the same as on the disc, but '''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 identical. 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? | In the end, with the exception of that slight HF dip, I get amplitudes almost exactly the same as on the disc, but '''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 identical. 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? | ||
Revision as of 00:00, 3 March 2018
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. In Windows I must make sure the recording device is set to 16/48, otherwise the Roadie or its drivers do some horrendous resampling. Don't use the Roadie in 44.1 mode, I guess.
I got a slight level boost and added broadband noise when I captured through the MME interface. So instead, I used ASIO4ALL to create an ASIO bridge, and configured it to not resample. In Audition, I set the input audio device to the ASIO4ALL version of the Roadie.
Even with this (ASIO4ALL, 48 kHz rate), I still get some mirror-imaging above 22.05 kHz, so there is still resampling happening. It goes away after I use Audition to bring the sample rate back down to 44.1.
Also, the high end rolls off above ~18 kHz, no matter what I do. It may be Audition's filters or it may be the Roadie, who knows.
In the end, with the exception of that slight HF dip, I get amplitudes almost exactly the same as on the disc, but 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 identical. 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.
