[FFmpeg-user] Capture Audio only from an Output Device?

[Moritz Barsnick]

On Wed, May 24, 2017 at 14:07:50 +0200, Jan Petersen wrote:
> Can I use ffmpeg to capture these outputs and stream it in PCM wave to a
> Linux box for further processing? Or can ffmpeg only capture imputs?

Usually, outputs drivers don't reveal the data they get, and can't
provide it back to the user. I believe I have heard of special drivers
for that, but they perhaps don't always work.

Have you given google a shot? This comes up at the very top and even
mentions a welcome exception for WASAPI:

https://www.howtogeek.com/217348/how-to-record-the-sound-coming-from-your-pc-even-without-stereo-mix/

> There is no WASAPI implementation at all, is that true? Or is there
> something available?

Oh, even better than that google hit above:
The people who provide the "screen-capture-recorder" dshow device
driver also provide a WASAPI loopback driver:

https://github.com/rdp/virtual-audio-capture-grabber-device

There is also an ffmpeg example in the README, along with tons of other
hints.

Moritz