Question Regarding USB Transfer Mode

[rjw57]

I am investigating the sometimes poor performance of my usb audio (occasional clicks and pops). My setup is USB output from port 5 of one of my two mobo based usb hubs (Intel 6 series/C200 series usb enhanced host controller) to a Musical Fidelity V-Link II (96 kHz) usb to spdif to one of my Integra DTR-40.2's optical inputs. I downloaded a program called USBlyzer in order to capture the stream and see if there were any anomalies (or at least what I perceive to be anomalies). In doing so, I discovered a couple of things:

1) my transfer mode is isochronous (i thought the MF Vlink supported async?)

2) when "stopping" the music via a "stop" button in my music software (jRiver or Rdio), I see that there is a problem with this as reported by the USBlyzer software. Specifically, I get a "cleanup" request from "audiodg.exe" whose supporting driver is "usbaudio" that results in an "Invalid Device Request". I next get a "cleanup" request from "audiodg.exe" whose supporting driver is "ksthunk" that results again in an "Invalid Device Request". The capture output is attached for those interested (jpg form).

 

My question is this... what am I doing wrong here that I am having driver issues and that I am not transferring in async mode? I apologize ahead of time for my ignorance regarding usb transfer protocols, but I would sure like to understand this better. Thanks in advance.

 

Bob W

[tubesound]

Clicks and pops are usually caused by not enough buffer allowed in your music player or if you're streaming the music wirelessly.

[sjoc2000]

Hello rjw57;

 

Key here is being able to read your data capture, but the thumbnail is too small. Please post a larger one that can be read, or pm me one with some data.

 

Jim

[jhwalker]

Hello rjw57;

 

Key here is being able to read your data capture, but the thumbnail is too small. Please post a larger one that can be read, or pm me one with some data.

 

Jim

 

If you click on the thumbnail, it expands to almost full-screen - easily readable

[sjoc2000]

JHW

 

Hehe, guess I did about everything to it, except just l. click on it, thanks jhw. This getting to be an old guy, guess I'm not always with it. You have a merry Christmas. :0)

 

Jim

[sarcese52]

The V-Link is only an interface converter that supports asynchronous transfer, the Dac in the Integra is what is Isochronous. Get an inexpensive Dac such as a Cambridge Dac Magic Plus or the Musical Fidelity V Dac II which will replace the V Link and the Integra Dac and use an analog input.

[Audio_ELF]

It's simple (sort of.

 

Isochronous is not the opposite of asynchronous. They refer to different parts of the USB chapability.

 

As I recall isochronous means that there is a portion of the bandwidth assigned to the USB Audio transfer.

 

Asynchronous on the other hand refers to the ability of the DAC (or USB to SPDIF interface) to control the flow of data.

 

I believe http://www.dcsltd.co.uk/assets/dCS_Guide_to_Computer_Audio.pdf explains in more detail.

 

Eloise

[iago]

1) my transfer mode is isochronous (i thought the MF Vlink supported async?)

 

The communication channel between the controller and the audio device uses isochronous mode, that means a guaranteed bandwidth is reserved from the packet stream for this channel. The endpoint(s) using this channel request and receive data asynchronously. Thus you will see an isochronous connection to the V-Link, even if it operates asynchronously.

 

The requests captured by your tool are related to Windows driver internals. Finding errors on that level without a debugger might be a challenge ;-)

 

Are you using kernel streaming currently? Try using different protocol stacks (aka audio output modes) and see if you can eliminate the problem.

[sjoc2000]

1) my transfer mode is isochronous (i thought the MF Vlink supported async?)

2) when "stopping" the music via a "stop" button in my music software (jRiver or Rdio), I see that there is a problem with this as reported by the USBlyzer software. Specifically, I get a "cleanup" request from "audiodg.exe" whose supporting driver is "usbaudio" that results in an "Invalid Device Request". I next get a "cleanup" request from "audiodg.exe" whose supporting driver is "ksthunk" that results again in an "Invalid Device Request". The capture output is attached for those interested (jpg form).

Bob W

 

rjw57;

 

When using the software you describe, it does exactly the same thing here, and gives the same messages with a perfectly working system when I pause or stop a track, so it is not likely that those messages backgrounded in pink (?) are telling you anything.

 

"Isoch" is just one of the descriptions of output requests. If you run your analyzer on your mouse function (with in and out messages) for a period of time, you will see isoch used to describe every output request.

 

But, your V-Link should be making "in" requests (part of it's asynchronous function), which I don't see in your example. As tubesound previously stated, it is likely this is a buffer problem. Possibly a stacking/buffer function problem exists in your pc, causing the V-link to malfunction.

 

There is a reference to similiar problems with audio/video on the net, and one potential fix.

 

How to Fix Audiodg.exe High CPU Usage Error « Information & Resources To Fix Common Computer Problems

 

I would also run cc cleaner if you haven't cleaned the pc recently. This program also has a registry fix and repair. Maybe you'll get lucky and one of these simple procedures will clear up the problem. If not maybe a usb expert around here will show up... :0)

 

Merry Christmas,

 

Jim

[rjw57]

Thank you everyone. While waiting for the help you have all provided, I began to realize that the isochronous transfer mode was, as iago describes, a method of ensuring bandwidth rather than a method of transfer timing. Many thanks to sjoc2000 though for a potential fix. I greatly appreciate all the input and I hope that a "usb expert" will show up as well so that I can learn more about troubleshooting the usb audio interface. Merry Christmas to all that celebrate!