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Getting audio from your SDR to a program on the same PC (picture heavy)

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Token

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#1
First things first, I am not a computer guy, I am a hardware guy (mostly tube type), what follows is just what I have noticed and found to work. I make no claims to being any kind of expert, just a sometimes frustrated user that might have encountered the same kind of problems as other users, and might have a solution for some of those other users. If I am making a major error I am sure someone will point it out and we can all learn. If there is an easier way to do the same thing then I hope someone will speak up.

A question that comes up regularly is: How do I get the audio from my SDR to a piece of recording or decoding software on the same PC?

Many times the suggestion is to get a program like VAC (Virtual Audio Cable) that is designed specifically to do this. I have never yet used VAC or any program like it. So far I have always been able to achieve the same results using only the software provided under Windows, and using the "default record source" that has been a part of Windows for a long time. Default record source just tells Windows what input to look at as its primary recorded sound input, but also this is what can be sent to almost any software in the PC, not just recording software.

The following posts are not going to answer the question for everyone, but it does work on most PCs that I have tried, depending on the specific hardware and device drivers involved. I know that some older sound cards do not support this operation, and some modern hardware does support the operation but the drivers are not configured for it, leaving the user potentially high and dry.

Over the years I have set up dozens of machines to record audio from an internal source. Currently here at the house in the radio listening area I have 6 PCs running 7 SDRs, and every PC can record the audio or decode from its associated SDR/s. The operating systems used are Windows XP Pro (3 machines), Vista (one machine), and Windows 7 Ultimate (2 machines). Only one machine gave me significant trouble setting up the audio, one of the Windows 7 machines included a driver that did not support the required mixing, and I had to resort to editing the .inf file associated with the sound card.

In the planned posts I will not be covering the specifics of the software you want to use for decode / record, there are far too many possibilities out there. However I find that in most cases all you have to do is set up the audio input of the software (such as fldigi or similar) to use the "default recording source" or "primary capture device", some wording along those lines, varying with each piece of software. I suppose individuals could add specifics for each piece of software as the questions come up.

There may be variations in what the screens look like in your specific instance, but the general idea should be similar to what I lay out in the following posts. I will do Windows XP first and then Windows 7. Maybe later I will include Vista. I have not tried this under Windows 8, but I do have a machine here with that OS and I might try it and see some day.

Lastly, although this is nothing but selecting intended functions under the OS I am not responsible if you brick your sound setup following these guidelines. I would suggest before you make any potentially intrusive adjustments that you create a Restore Point with your current or known good configuration.

T!
 

Token

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#2
Setting up for "Wave Out" or "Stereo Mix" as your default record source under Windows XP.

Generally XP is very easy to set up for Wave Out or Stereo Mix (there are other possible similar names used with some sound card drivers, I find "Wave" to be the most common) as your default record source.

On the Desktop locate the "Systray" in the lower right hand corner of the screen. Locate the Speaker icon in the Systray. The drivers for some sound cards change this and supply a different control panel, if that is the case you might have to modify what is described here a bit.




After right clicking on the speaker icon pull up the menu and left click on "Open Volume Control".



The "Volume Control Panel" should now be open. Under "Options" menu pull down to "Properties" and left click that.



You will now want to make sure you are setting the right sound card input, if you have more than one sound card. You will also want to select the "Recording" option, this will bring up the possible record source devices. And then you will want to check mark any sources you might want to use for recording. I the case of what we are trying to do here it might be "Stereo Mix" or "Wave Out". In the case in the pictures "Wave" is the right answer. After you have made your selections hit "OK".



You are now in the "Recording Control Panel". Put a check mark in the "Select" box for the source you want the audio to come from, and adjust the Mixer sliders as needed to control the recorded audio levels. Close the window and you should be good to go, assuming your Decode / Record software is set to take the Windows Default Recording source.


I hope that helps someone. If not, well it was free advice, and worth every penny ;)

T!
 

Token

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#3
Setting up for "Wave Out" or "Stereo Mix" as your default record source under Windows 7 Ultimate.

Widows 7 is sometimes a bit more difficult to set up for the default record source. 7 has a tendency to hide features from the user, and this case is no exception. Specifically disabled or unused sources are sometimes not immediately seen in some control panels, and unless you know to go looking for them and turn them on you might not think their use is even an option.

It the lower right corner of the Desktop locate the Systray (note that I have my desktop set up to look like XP). In Systray right click on the Speaker icon.



Move the cursor up, hi-lite Record Devices, and left click on it.





The Sound Control Panel should open, with the Record tab selected. This will show you all the record sources that you could select. Windows 7 often hides unused sources by default, so you may not see many sources there at all, or they may all show up, depending on your settings. The below image shows nothing but a Microphone selectable, and was the original configuration for my laptop audio.




Obviously the Microphone as an audio source is great for things like Skype, but does not work too well if we are trying to get the audio from an SDR into recording or decoding software. Right click in the white area under the Microphone, were nothing else is seen. This should bring up a pop-up with two choices, "Show Disabled Devices" and "Show Disconnected Devices". Select both of these options.




If at this point Stereo Mix ( or something similarly worded to that ) is not a selectable option then you may have a problem. In the case of my laptop it was not a selectable option until after I went in and edited the driver a bit, a process that is a bit lengthy and I will not cover here. You may, or may not, be able to do something similar, depending on your hardware and drivers.

Select the "Stereo Mix" icon to hi-lite it and then press the "Set Default" button.




If you have been successful there should be a green bubble next to the Stereo Mix icon and there should be a check mark in the bubble. Hit the "OK" button and the control panel should close.



If all has gone well the Stereo Mix should be your default record source, and if your record / decode software is configured to take its audio from the Windows Default Record source you should be good to go.

Again, I hope this helps, but make no guarantees.

T!
 

ka3jjz

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#4
This is an interesting writeup - one that should go to our wiki, since this thread will eventually scroll off.

I'd do the work but I'm going to be switching ISPs in the next couple of days, so I have a great deal of cleanup to do. I'd touch base with W9BU and let him know about this, if he hasn't seen it already. It's potentially very valuable information that should likely be linked from our Software Defined Radio wiki

Mike
 
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#5
Setting up for "Wave Out" or "Stereo Mix" as your default record source under Windows 7 Ultimate.



T!
Outstanding - was much interseted if this method when I noted your mention of it in another thread...
Only have a few minutes before work, but can report inital findings: Definitely decoding P25 (still needs tweaking) using setero mix as default rec.device with HDSDR/DSD160/RTL2832U/R820T/Win 7 Ultimate 64 bit/ Intel motherboard on board sound.

Up to this point was using VAC or VBC (freeware). Have several different OS/SDR setups, will give those a try too...
 

blantonl

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#8
Great job Token - I concur with Mike this definitely needs to be a Wiki article. Let us know if you need assistance writing one up.
 

blantonl

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#9
With that said, I'll be the first to say that for the price, Virtual Audio Cable (VAC) is an indispensable tool for SDR, recording, and decoding - between computers as well.
 

foxtail

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#10
Well after setting this up for stereo mix...how do I get it to work with SDR#. I've set levels, turned on listen...just can't get it to output to unitrunk for a control channel. On board realtek sound card. So who's has this working...maybe a hint? Thanks.
 

foxtail

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#12
I don't see anything under your audio in sdr. I have it setup for stereo mix but get no levels on it. I hear the control chl but not decoding. My sdr audio is set for input (mme) windows sound map and output is set to realtek hd optical.. Try unitrink audio port to stereo mix...nothing. Works with vac when installed
This just bug the crap out of me that I can't get a SIMPLE piece like this to work...
 

ka3jjz

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#13
Dumb question - are you using a laptop here? is that stereo mix enabled in the volume master controls, or in Control Panel? Is it muted? It's not unheard of that, at least with laptops, these are left disabled.

It depends on the operating system and how the device drivers for these inputs were defined by the manufacturer, but those 2 places are logical places to start to look

HTH...Mike
 

foxtail

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#14
OK..so after going to a working backup drive with vb cable as the output it works. Sdr program with vbcable out will show me cc info. Changed stereo as the default in recoder. Stereo mix does not show up in sdr as an output! How do you get st-mix to show up in sdr so I can output the sound to unitrunk. This has to be really simple but I just don't get it!! Would like to try st-mix but may have to stay with vbcable.
 
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#15
Token, I had a problem of no "Stereo Mix"

in my Windows 7 Ultimate. Followed your informative posts, but still no Mix. Searched the web and found a great YouTube fix for anyone else who may have this problem. It's a short vid about ~3 minutes long and you have to download the driver from Realtex dot com. But it is a fix for us without the "Stereo Mix"!

Windows 7 Stereo Mix Tutorial/ How to fix missing stereo mix - YouTube

Now all I gotta do is play around some more with the SDR.
 

Token

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#16
in my Windows 7 Ultimate. Followed your informative posts, but still no Mix. Searched the web and found a great YouTube fix for anyone else who may have this problem. It's a short vid about ~3 minutes long and you have to download the driver from Realtex dot com. But it is a fix for us without the "Stereo Mix"!

Windows 7 Stereo Mix Tutorial/ How to fix missing stereo mix - YouTube

Now all I gotta do is play around some more with the SDR.
That video and advice will work if your hardware is compatible with that specific driver. Glad you found an answer for your situation.

If you do not have Stereo Mix after doing what I posted then there will have to be some other technique used, the specifics of that technique will depend on your hardware. This means many possible answers, each one depending on your hardware and beyond the scope of a general "how too".

As I said before, on one of my machines I had to edit the .inf for the driver to enable the Stereo Mix. I was able to sue the same driver I had, but forced it to think it was in another installation. Obviously that will not work for everyone, probably not even most instances.

T!
 
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#17
Thanks Token, works great. I tried using a VAC but didn't have any success. I have been trying to use DSD 1.6 and a rtl dongle and SDR Sharp for APCO 25 now I have that ability. So far the only problem is the decoding the actual AP25 signal, I get 90% noise and 10 audio, I guess I have some tweaking to do in DSD, thanks again.

Moonbounce.
 
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#18
Technical Note

Just a quick follow-on to Token's article...

A lot of computers do not have an add-in sound card like they used to. Those old "sound cards" have been reduced to a single microchip on the computer motherboard.

A company called Realtek has pretty much cornered the market here. Their audio chipset is simple and it works well for what it's intended. It costs next to nothing for the motherboard manufacturer's to add this simple component.

Windows 7 has generic software that supports the Realtek chipset. To get the most out of the chipset however, you must use the Realtek audio software. Their software contains two parts -- the audio drivers and audio support applications. (This is the little red speaker icon in the lower right corner.)

Here's the direct link to Realtek's download site: Realtek

The Realtek software doesn't expose a "WAVE" device like the Asus software. I believe Creative also uses a "WAVE" device. Without going any deeper this device is similar to VAC in that it routes active audio to and from applications. Asus and Creative have their own software applications that rely up on this device for various features.

From my experience, I had many issues using DSD and the Realtek audio device. I finally upgraded to an Asus Xonar DX PCI-E sound card and my problems went away.

For the owners of a Realtek chipset, you will certainly need the VAC software. It *must* be a registered version to get any real success as the demo version has the word TRIAL repeated over any audio that is passed through. This will screw up most decoding or recording.

For most 3rd party sound cards like a Creative or an Asus, you may not need VAC. I still use VAC as I had already purchased it -- but for me, I can decode HF data with my sound turned off -- and the audio is still passed through.

If I were to just use the WAVE device turning off my volume turns off the WAVE volume as well.

VAC has a lot of benefits and has so far been quite stable for me. I think he has had version 4.12 for a long time now. It's stable and well worth the purchase price -- especially if you have an on-board Realtek device.

As others have pointed out, the audio plumbing changed significantly from Windows XP to Windows 7. This is why it's important to use software written specifically for your current operating system.

In some ways, using XP was easier but the changes in Windows 7 have also given applications greater flexibility with control of audio devices.

As Token has mentioned, the mixer option may work for you. I think this is dependent upon the actual chipset version your system has... older versions probably don't support the mixer. I just checked my HP machine here at work and it does have the mixer option disabled by default.

If you have the extra cash I highly recommend the Asus sound card. It's far cheaper than a Creative and the sound quality is excellent. Far better than any on-board sound option out there.
 

Token

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#19
nick, the pictures of the Win 7 machine (a Gateway desktop) in my post is equipped with Realtek High Definition Audio (notice it says that right in the control panel window). As you can see in the pictures I got it working without a VAC. However, I did have to go in and edit the .inf. It turns out the capability IS included in many (I have heard most, but cannot confirm that) Realtek hardware and drivers, but is commented out in the .inf. I was also successful doing the same thing in one of my laptops, which has Realtek.

T!
 
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#20
For the owners of a Realtek chipset, you will certainly need the VAC software. .
See post #11, realtek on board chipset with Win7 generic drivers working with Stereo Mix (no VAC/VBC).

Also, Stereo Mix working on another system, Intel MB onboard realtek chipset sound - generic Win7 drivers, no other software...
 
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