Is All SPDIF Audio Output the Same?

CyberSpaZtiK asks: "I am going to build a Linux audio appliance to hold my music collection in various formats and for output to my stereo system. Because of a probable lack of Linux availability or support for audio cards with high quality D/A converters and low-noise electronics (or am I mistaken?), I want to keep the output path completelely digital by using a card with SPDIF output. However, it occurs to me that I actually know very little about SPDIF - are all SPDIF outputs made equal? Can I expect every SPDIF interface to emit the exact PCM data of the source audio, or are there over/under-sampling/aliasing, etc. issues that you sometimes get with digital signal processing? What do I need to understand about SPDIF and/or other digital output interfaces to make an informed decision?"

Comments

Re:Answer

[Anonymous Coward]

1. Slashdot actually is a news site, not a support number.

Then why do they have an "Ask Slashdot" section?

Re:Jitter is a bunch of crap

[stienman]

Jitter is a problem for electrical engineers and programmers. By the time we're done with the system, you won't be able to tell whether there is any jitter or not, nevermind how much. Regardless, there WILL be jitter.

Unless, of course, all your units have synchronized clocks, or each have their own atomic clock.

Unlikely, to say the least.

Jitter is not a problem the average prosumer really needs to worry about, nevermind the average consumer.

The audiophiles who care about it care the same way about their tubes, oxygen-free cables, and green highlighters. Whatever gives you a warm fuzzy feeling, man.

But, technically, it does exist, and it is a problem that results in either doubling up on samples, skipping samples, or some sort of macabre clock synchronization scheme that only ends in tears.

Only, technically, that's not jitter either.

-Adam

Re:Use TOSLINK instead

[farnz]

Bullshit. Complete and utter bullshit. In decent equipment, when you reclock, you use a PLL to lock to the existing signal, and create a binary bitstream in a buffer; you then use your own clock to pump bits out of the buffer. So long as the jitter isn't too bad, there will be bits going in often enough that the buffer never drains. All that then matters is the quality of your clock.

Jitter is an issue for equipment designers; it is not an issue for equipment users. With the aid of a decent lab, you can verify this in double-blind tests; jitter either makes no difference at all, or causes the sound to glitch.