|
Computer Audio Asylum Music servers and other computer based digital audio technologies. |
|
|
|
Computer Audio Asylum Music servers and other computer based digital audio technologies. |
|
In Reply to: RE: 1) without a doubt, #1 is digital source jitter posted by phofman on April 8, 2012 at 00:03:41:
Uncontrollable (independent) input, controlled output to fit the input pace
-----------------------------------------------------------------------
In the buffer usage of the SPDIF receiver there is uncontrolled jittery input, with output clock being continuously adjusted to keep the buffer fill optimal via advanced PLL. No fixed clock at the output, unlike in the previous scenarious. And that is a major conceptual difference.
Again, I think we're in agreement but you are using what I consider to be the edge cases to argue a point. It's a valid point; I'm afraid I'm not the best at articulating what I'm thinking.
The difference between adjusting input or adjusting output only kicks in if input jitter is too high, forcing the WM8804 output clock to move past its "intrinsic" jitter specification.
However in both cases, attempting to control the output rate or the input rate, if there is data in the buffer then your output will be reliable and identical. Assuming that the small amount of jitter at output is negligible, then it doesn't matter if you are adjusting the input or output rates. (In the case of a uncontrolled input, you want the buffer to stay in the middle, so you avoid underflow or overflow.) Of course, one can reasonably argue that it is a lot easier to keep data buffered when using a computer and requesting data, since a computer can have much larger buffers.
My comparison to streaming A/V could be described as follows, and had more to do with A/V bitrate than frames per second.
If you don't have a super fast Internet connection, then even if you are controlling when you ask for data, if you don't get the data in time, you are in trouble. So you adjust the bitrate instead. The corresponding way to achieve the same result when you are adjusting the output clock is to have a super big buffer (so you don't have to adjust the output clock).
A computer and audio DAC falls into the category of a super fast connection. Wolfson states that their buffer is big enough to handle incoming jitter of 0-0.5UI @ 1kHz with 50ps of output jitter which they categorize as negligible.
I hope that gets across what I was thinking a little clearer. I completely agree with what you said; I was just thinking something different. And maybe still not explaining it very well.
This post is made possible by the generous support of people like you and our sponsors:
Follow Ups
- RE: 1) without a doubt, #1 is digital source jitter - Wesley Miaw 05:23:48 04/08/12 (0)
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2025, Audio Asylum, all rights reserved ]
