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Digital Drive Upsamplers, DACs, jitter, shakes and analogue withdrawals, this is it. |
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Digital Drive Upsamplers, DACs, jitter, shakes and analogue withdrawals, this is it. |
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In Reply to: Depends on What Type.............. posted by Todd Krieger on July 15, 2014 at 22:18:02:
"The "jitter rejection" claim was also bogus because the jitter error at the input gets embedded into the signal as noise artifacts during conversion. (Once this noise is embedded, it cannot be undone.)"
You are confusing two different potential sources of jitter: (1) timing errors in the conversion of the original analog waveform to a series of digital samples, (2) timing errors in the arrival of digital samples at the input of the ASRC block in a DAC.
The former occurs during record. Timing errors at this point are embedded into the digital file and will be there regardless of how the file is played.
The latter occurs during playback. Errors in timing at this point have at best a minute effect on the samples output by the ASRC converter. They have an effect only in as much as jitter affects the determination of the "average" input sample frequency. This average sample frequency is calculated using a very narrow bandwidth digital phase lock loop. To the extent that the DPLL bandwidth approaches zero the timing of input samples will have no effect on the values output by the sample rate converter, hence the presence of jitter rejection. To the extent that the bandwidth is not zero the jitter rejection will be less than perfect. All audio is less than perfect, so this is not an argument that the jitter rejection is "bogus". Unfortunately, doing the necessary complex interpolation is computationally complex. This offers lots of opportunity for ASRC to sound poor for reasons other than jitter rejection. Many of these problems exist with any sample rate converter.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
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Follow Ups
- RE: Depends on What Type.............. - Tony Lauck 07/16/1411:29:39 07/16/14 (3)
- RE: Depends on What Type.............. - knewton 12:59:03 07/16/14 (2)
- RE: Depends on What Type.............. - Tony Lauck 14:07:04 07/16/14 (1)
- Moot Point........ - Todd Krieger 17:33:05 07/16/14 (0)
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