VirtualDub and Directshow Crossbars - restoring missing sound
 

I noticed something tonight that "might" be a real thing and help people who use VirtualDub for capture.

Sometimes you can capture video but not audio.

1st - I assume your capture device not only decodes audio, but also captures it independent of using a separate sound card.

2nd - I assume you have turned on "audio playback" to test or set the levels (before) turning that off to perform a "Real" capture session so that you do not drop frames or loose audio video sync (lip sync) during a real capture.

Under the [video] menu is an option to open the 'Crossbar' control dialog for the selected capture device.

it usually opens "focused" on the video [input] and [output] panels with one of the video inputs defaulted

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Here is what I noticed.

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Instead of moving from [Left to Right] selecting the video Input and video Output preferences, "like s-video to video output"

If you move from [Right to Left ] and start with the audio "output" first > drop down and select the audio out.

Then the right side audio "input" will populate with a selection of input pins for the crossbar filter.

Normally they say something like [Tuner Input, Line Input, etc..]

This is important because some capture devices do double duty as a Tuner as well as a Set Top capture device and will default to the "Tuner Input" rather than the "Line Input". When composite or s-video is selected as the video source, curiously the Tuner audio is silent.. so you have no indication the wrong audio input is selected.

Choosing the "Line Input" and hitting apply and ok to close (often-"ish") seems to resolve missing audio capture for me on several devices.. even those that are not combo tuner and analog capture devices.

(This-Is-Totally Backwards) to intuition.

Its not a cure all or for all capture devices, its a quirk in the way that Directshow filters expose video and audio choices.

.. something to try before you give up