Decklink: Using audio source only (with no video source) ?

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mefab

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Decklink: Using audio source only (with no video source) ?

PostTue Nov 13, 2012 4:36 pm

Hi all,

I'd like to know if it is possible to use the Decklink analogic audio source alone: without using the Decklink video source or with another video capture card on the same pc ?

I tested with Flash Media Live Encoder 3.2 and it doesn't seem to work.

Thanks in advance.

Best regards,

Fab
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Joshua Helling

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Re: Decklink: Using audio source only (with no video source)

PostTue Nov 20, 2012 8:42 pm

It does not work. We need a video source as the timing for the audio. So you will need to have both. Typically it will not be hard to disregard the video after capturing.
Joshua Helling

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Pedja Djurdjevic

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Re: Decklink: Using audio source only (with no video source)

PostSun Dec 16, 2012 2:39 am

Could you elaborate on the SW setup for using Decklink just as a regular audio recording device. If one is programmatically or via DirectShow graph editor constructing their own graph similar to the C/C++ video capture example in the SDK, what it the minimal set of DirectShow filters required to accomplish your idea? Is there an graph sample that exemplifies this?
For the timing source, is it enough to have just any timing source or it has to be a Decklink video filter present in the graph, and in that case, does the physical HDMI connection and stream have to be there, for example by looping back the HDMI out?

Regards.
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Sarah Jones

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Re: Decklink: Using audio source only (with no video source)

PostSat Dec 22, 2012 12:55 am

If you are inputting an audio signal via the analog inputs on the DeckLink card, you will need to connect an analog video connection or even SDI or HDMI (it could even be black video if you want, but the video signal must be compatible with the frame rate and resolution supported by your particular DeckLink card). This video would time the audio and then allow capture. If no video source is present, the audio will not input. Just set your control panel settings accordingly for whichever video type you will be connecting.

For specific SDK and developer related questions, please join our developer list here: http://lists.blackmagicdesign.com/mailm ... -developer
Sarah Jones

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Pedja Djurdjevic

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Re: Decklink: Using audio source only (with no video source)

PostSat Dec 22, 2012 5:52 am

In this case there is only an audio source present, so I suppose it's OK to loopback DeckLink card HDMI out into HDMI in and just stream black frames at some minimal resolution/frame rate? Since the audio still won't show as regular WDM recoding device, I presume the only way to programmatically extract audio (to wave) is via the DirectShow graph? Does the graph need to contain any timer sources or just one DeckLink audio filter?

Thanks.

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