CaptureWidget - Page 8 - diyAudio
Go Back   Home > Forums > Design & Build > Equipment & Tools

Equipment & Tools From test equipment to hand tools

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 16th March 2013, 05:40 PM   #71
borges is offline borges  Norway
diyAudio Member
 
Join Date: Dec 2003
Location: Oslo, Norway
Question: Which PC software would handle the recording? The reason I'm asking is that beyond 24/48 we will not benefit from the built-in USB audio drivers in Windows.

Also: how is the sample rate set? Is the host able to follow anything the device sets up, or will the host decide the sample rate? If the latter is the case, may the device request a sample rate change?

How these two things are handled will influence the design significantly.

BÝrge
  Reply With Quote
Old 16th March 2013, 05:42 PM   #72
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
The driver is critical to successful operation. For HW guys this is the biggest hurdle to get over. But what has killed many projects and products.

Ok also with 1 [or 2] sample rates. Just a black box that interfaces properly and smoothly and works every time on WIN 7.

-Richard

Last edited by RNMarsh; 16th March 2013 at 05:45 PM.
  Reply With Quote
Old 16th March 2013, 05:48 PM   #73
borges is offline borges  Norway
diyAudio Member
 
Join Date: Dec 2003
Location: Oslo, Norway
The works every time with Win7 you get up to 24/48 with HW based on the Audio Widget. Based on closed-source USB audio class 1 you get 24/96. That's due to various fundamental bandwidth limitations.

The other alternative is to use an ASIO driver on Win7. For playback this works very well with the Audio Widget. For recording I have no experience.

I have recently initiated the winuac2 project which aims to create an open-source USB Audio Class 2 driver for Windows. That is going to be a lot of work. Any driver heads out there are very, very welcome to join in!

BÝrge
  Reply With Quote
Old 16th March 2013, 05:50 PM   #74
1audio is offline 1audio  United States
diyAudio Member
 
Join Date: Mar 2004
Location: SF Bay Area
Blog Entries: 3
usually you must manually set the software to the hardware/system sample rate. And on Win 7 you must manually set the system to match the hardware or sample rate converters wreck everything.

ASIO may be different. I have been using the ASIO driver from EMU and it works with ARTA but I can't access the EMU control interface any more (software bug, after reinstall even).

Typically the PC SPDIF inputs detect the incoming sample rate and lock to it. Some cards have Async src's on each input- not what we want. The PC sound infrastructure is designed to handle "async" input.
__________________
Demian Martin
Product Design Services
  Reply With Quote
Old 16th March 2013, 06:15 PM   #75
davada is offline davada  Canada
diyAudio Member
 
Join Date: Jul 2004
Location: Fort St John, BC Canada
Quote:
Originally Posted by 1audio View Post
Richard-
Software would require a connection to a PC and some software on the PC, just to switch the sample rate. It would also require an isolator and who knows what else.

The bitscope is the most straightforward way to see things like 16 bit/24 bit and which level is going over the link. I do this now with a scope monitoring the output of a digital receiver, sync on L/R clock and look at data. But a row of LED's would be just as useful and less cumbersome to set up. One of the challenges is to see what is coming from the ADC and if its what you expect.

The Juli@ card uses a 4116 to receive spdif and it seems to be able to figure out the sample rate. I'll dig deeper. The Crystal and Wolfson receivers are viable options as well.

My thought of having an on board oscillator for calibration is like the calibration output on a spectrum analyzer. Its for confidence in measurements. Not necessary but nice to have.
If the ADC is a fixed 24 bit depth then only the sample rate can change why would we need to monitor bit depth. The sample rate can be extracted from the L/R clock frequency or the bit clock. It just a frequency counter. If the Atmel can receive an SPDIF then its demodulating the biphase and I2S info is available. Set up one of the timer modules and do a compare. It doesn't need to be checked continuously and it can run at the lowest priority. A bit can be set in some user register to represent the sample rate. The firmware can just check the register bit for change.

"My thought of having an on board oscillator for calibration is like the calibration output on a spectrum analyzer. Its for confidence in measurements. Not necessary but nice to have."

Do you mean an offset low level marker for comparison? Is this for the confidence of measurement like what Victor does with his OSC measurements?

It's a great idea but does it have to be on board. We could include this as an AUX mixer at the analog input and specify a curtain cal level.
__________________
David.
  Reply With Quote
Old 17th March 2013, 02:21 AM   #76
davada is offline davada  Canada
diyAudio Member
 
Join Date: Jul 2004
Location: Fort St John, BC Canada
Quote:
Originally Posted by borges View Post
Question: Which PC software would handle the recording? The reason I'm asking is that beyond 24/48 we will not benefit from the built-in USB audio drivers in Windows.

Also: how is the sample rate set? Is the host able to follow anything the device sets up, or will the host decide the sample rate? If the latter is the case, may the device request a sample rate change?

How these two things are handled will influence the design significantly.

BÝrge
Hi Borge,

These are good questions.

With sound cards the apps send a request to the driver and the driver handles the hardware control. There's a small app here ASIO that connects to any ASIO driver, displays information about it and runs a through put test.
Most ASIO drivers have there own control panels which can set parameters as well.

The EMU1212 dsp application is protective and won't allow other apps to change the sample rate. If the sample rate is changed by the DSP app it doesn't change in ARTA.
This doesn't seem to bother ARTA but ARTA continues to display the samples at the rate it was last set for. It doesn't seem to matter if the hardware has a fixed sample rate.

We need a full ASIO driver in mono at least or 2 channels to make this work on a Win OS
I think the ASIO for the Audio-Widget is minimal. Is this correct?

I would say no the host can't follow the sample rate because this was not expected by the app author. It's unusual functioning for a sound card.

I would be happy with an ASIO driver that gets a stream going to the application software. If it doesn't cause a crash then less functionality doesn't matter.

Cheers,
__________________
David.
  Reply With Quote
Old 17th March 2013, 08:35 AM   #77
mkc is offline mkc  Denmark
diyAudio Member
 
Join Date: Jun 2002
Location: Denmark
Quote:
Originally Posted by borges View Post
Question: Which PC software would handle the recording? The reason I'm asking is that beyond 24/48 we will not benefit from the built-in USB audio drivers in Windows.
BÝrge
Hi BÝrge,

Please correct me if I'm wrong, but the 24/48 is not a limitation in windows, right?

As far as I know Ayre doesn't need a special driver when using their QA-9. Only for the QB-9, when running 192KHz, but that's another story.

Mogens
  Reply With Quote
Old 17th March 2013, 08:43 AM   #78
borges is offline borges  Norway
diyAudio Member
 
Join Date: Dec 2003
Location: Oslo, Norway
Hi Mogens,

The built-in Windows UAC1 driver handles 24/96. But in the AVR32 case there is a hardware limitation which sets this at 24/48.

However in UAC2 we can go to 32/196. This is limited by the 16Mbps serial interface of the AVR32. But it requires a driver. An ASIO driver for playback is in place and works routinely for the Audio Widget.

I don't know how well the ASIO driver works for recording. But without writing a Windows UAC2 driver, there will be no "Found new Microphone" above 24/48 in a system based on the Audio Widget.

BÝrge
  Reply With Quote
Old 17th March 2013, 10:12 AM   #79
mkc is offline mkc  Denmark
diyAudio Member
 
Join Date: Jun 2002
Location: Denmark
Hi BÝrge,

Well, I think I saw a comment in one thread about migrating the Audio Widget to another processor. In case it's not something I have dreamed up, which would that be?

I have looked at two types in the past. The Atmel SAM3UC, as used on the Amanero board which does 24bit@384Khz, and the STM32F4 series. I think the latter even have 2 I2S ports.

Perhaps I could assist or do the porting of the Audio Widget to one of these, as a background project, if there is any interest?

Mogens
  Reply With Quote
Old 17th March 2013, 10:15 AM   #80
borges is offline borges  Norway
diyAudio Member
 
Join Date: Dec 2003
Location: Oslo, Norway
I'll let Demian answer that one.

In general, AVR32 isn't very well supported anymore, and $10 per chip even in high volume is a lot.

BÝrge
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



New To Site? Need Help?

All times are GMT. The time now is 07:54 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2