No Audio in Anything But Media Express

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AshTR

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No Audio in Anything But Media Express

PostMon Oct 15, 2012 3:57 am

I can't seem to figure out why, but when I open something such as VLC or VirtualDub, I have no audio using the Decklink Audio Capture interface. When I go into the Properties for it, I have the right amount of channels selected (2 ch, 48KHz, 16-bit) but the audio level monitors aren't moving up at all. I'm using a component setup and I've checked all settings in the Blackmagic Design Control Panel.

I've played with both output settings, and I have the input set to "Component Video & Analog RCA Audio" as it should be and video standard is as it should be at HD 720p 59.94, but even in the Control Panel there aren't any settings to modify under Audio Levels as well. The only thing to click in that is Reset Gain.

The odd thing is that I can use Media Express and record with no issues. Audio and video write properly to the file with both existing. There's no lack of audio there for some reason.

Does anyone know how to fix this or what I should try to fix it? It's really quite annoying.
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Chris Pearse

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Re: No Audio in Anything But Media Express

PostMon Oct 15, 2012 6:04 am

Hi Ash,

I don't think VirtualDub or VLC have any way to directly communicate with the card. So you may need to set Windows' default audio device to the DeckLink card. This is technically possible and it seems to work OK for me using the DeckLink HD Extreme 3D, I'm afraid I'm not sure which card you have. To do this you would need to go to the Sound section in Windows' Control Panel and select the Blackmagic Audio option, and there should be a button, or context menu to set this to the default.

However the way the card works is somewhat different to a typical sound card. It's not strictly intended to be used in this way. Any video application that has direct access to the card, such as Media Express, will take over the card's functions only for itself, meaning you won't be able to use something like Media Express and VLC at the same time. The audio would only be output from Media Express in such an instance. Audio capture without a video signal however is not possible.
Chris Pearse
Product Specialist
Blackmagic Design Japan
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AshTR

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Re: No Audio in Anything But Media Express

PostThu Oct 18, 2012 11:02 pm

Chris Pearse wrote:I don't think VirtualDub or VLC have any way to directly communicate with the card. So you may need to set Windows' default audio device to the DeckLink card.


That's funny considering the support manual says VLC is officially supported. Also, both VirtualDub and VLC use DirectShow so there shouldn't be any problem, but for some reason there is now. Normally I can just select either Decklink Video Capture and it works.

I'm just going to try an older version and see if that fixes the issue.

EDIT: Well, that didn't fix it. I've checked the audio levels as well and they don't go up, so for some reason audio isn't getting through, even though it gets through to Media Express. How strange.
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Mike Squires

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Re: No Audio in Anything But Media Express

PostSun Oct 21, 2012 4:34 pm

Have you tried recording something via VLC, and check the file afterwards to see if it has audio?

I know in Premiere Pro, the audio levels don't show up when capturing or previewing (very odd), but they do in Media Express. But when you actually capture, it does record the audio, you just don't get a visual recognition while it's doing it.
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Chris Pearse

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Re: No Audio in Anything But Media Express

PostTue Oct 23, 2012 7:56 am

Hi,

I think I may have gotten the wrong end of the stick and thought you were trying to play back, in which case there would be nothing direct to connect VLC or Virtualdub to the DeckLink card. But indeed it looks like you are trying to capture using the WDM filter, which is supported.

Indeed the WDM filter window might not show any audio in the meters, I don't believe that when using VLC, at the point at which you make those settings there will be any audio or video reaching the software. The true test would be to try capturing and see if any audio is captured. It's possible you may also need to alter VLC's advanced capture properties too to reflect the audio sample and bit rate required.

It would also be interesting to know if audio is looping through the card by connecting speakers or a monitor with audio to see if sound is coming through the card when in capture mode.

If you're still not getting anything I would suggest contacting support directly using the numbers here, and they should be able to determine where the problem is coming from.
Chris Pearse
Product Specialist
Blackmagic Design Japan

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