gaboo
100+ Head-Fier
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I've not given up on a FAQ yet, but with little time to write it, I've decided to "dump" most of the relevant links here.
Paper on CD Audio. Despite the name, it covers the basic concepts of digital audio: sampling, aliasing, quantization, dither, jitter. Good intro.
Julian Dunn was commissioned to write a series of four tech notes for Audio Precision, a testing equipment manufacturer. These are the most comprehensive, easy to read articles I found on the web on these "hot" issues. You should read them in this order (as they contain backward references):
Jitter Theory
ADC Measurements
DAC Measurements
AES/EBU & S/PDIF
From the same author, the famous S/PDIF flawed ? paper (1992).
Articles from Stereophile archives. Take the year into account when reading, generalizing comments about equipment should be viewed in that perspective.
Jitter, Bits, & Sound Quality (1990): their first stab at jitter, theory & simulations
The Jitter Game (1993): their first measurements
Jitter & the Digital Interface(1993): more of the same, better intro
Bits is Bits, but clock is clock (1996). Updated version of Julian Dunn's "S/PDIF flawed ?" paper.
Reducing jitter in the world of S/PDIF (& AES/EBU). From a manufacturer of such devices, but seems fairly unbiased.
Innards of a reclocking chip: CS8427. Basically: decoder, buffer, encoder.
Word clock is a simple, but non-standard addition the standard AES/EBU. It is mentioned in appendix B of AES11.
S/PDIF alternatives:
I2S allows the DAC to be the master clock. It only defines a bus, it's not a complete standard. Several physical implementations exist, most noticeable I2S enhanced.
USB Audio allows for both isochronous and asynchronous transfers. The asynchronous version completely eliminates transmission jitter, at the risk of buffer underrun.
Breaking news (10/23/04, thanks to 00940): Hitoshi Kondoh, from Burr Brown has writen a detailed article on the USB implementation of their PCM2702 USB DAC (adaptive isochronous mode), and how SpAct (basically a time-optimal PLL) came to be. The claim is that using SpAct one can achive both low jitter, and a fast locking PLL, thus avoiding noticeable startup delays. We're still waiting for part 3 of the article to show up online...
Firewire audio (IEC-61883-6) is unfortunately jittery.
More to come. Stay tuned, and please contribute!
Paper on CD Audio. Despite the name, it covers the basic concepts of digital audio: sampling, aliasing, quantization, dither, jitter. Good intro.
Julian Dunn was commissioned to write a series of four tech notes for Audio Precision, a testing equipment manufacturer. These are the most comprehensive, easy to read articles I found on the web on these "hot" issues. You should read them in this order (as they contain backward references):
Jitter Theory
ADC Measurements
DAC Measurements
AES/EBU & S/PDIF
From the same author, the famous S/PDIF flawed ? paper (1992).
Articles from Stereophile archives. Take the year into account when reading, generalizing comments about equipment should be viewed in that perspective.
Jitter, Bits, & Sound Quality (1990): their first stab at jitter, theory & simulations
The Jitter Game (1993): their first measurements
Jitter & the Digital Interface(1993): more of the same, better intro
Bits is Bits, but clock is clock (1996). Updated version of Julian Dunn's "S/PDIF flawed ?" paper.
Reducing jitter in the world of S/PDIF (& AES/EBU). From a manufacturer of such devices, but seems fairly unbiased.
Innards of a reclocking chip: CS8427. Basically: decoder, buffer, encoder.
Word clock is a simple, but non-standard addition the standard AES/EBU. It is mentioned in appendix B of AES11.
S/PDIF alternatives:
I2S allows the DAC to be the master clock. It only defines a bus, it's not a complete standard. Several physical implementations exist, most noticeable I2S enhanced.
USB Audio allows for both isochronous and asynchronous transfers. The asynchronous version completely eliminates transmission jitter, at the risk of buffer underrun.
Breaking news (10/23/04, thanks to 00940): Hitoshi Kondoh, from Burr Brown has writen a detailed article on the USB implementation of their PCM2702 USB DAC (adaptive isochronous mode), and how SpAct (basically a time-optimal PLL) came to be. The claim is that using SpAct one can achive both low jitter, and a fast locking PLL, thus avoiding noticeable startup delays. We're still waiting for part 3 of the article to show up online...
Firewire audio (IEC-61883-6) is unfortunately jittery.
More to come. Stay tuned, and please contribute!
