[FFmpeg-user] delay time in live ultrasound converter

[Michael Glenn Williams]

Wow that is so cool! Will ffmpeg generate ultrasound sounds to, or do we
know of a plugin or other that could do that, then feed the signal to
ffmpeg?

Thank you!

On Sat, Apr 18, 2020 at 9:48 AM Michael Koch <astroelectronic at t-online.de>
wrote:

> Am 18.04.2020 um 18:25 schrieb Ted Park:
> > I don't know where I can find bats nearby so I couldn't try it but how
> > does it work? The book makes it sound like you can use any mic, even
> > one built into a laptop for this? I suppose that's plausible looking
> > at a typical mic's frequency response graph, they are just cut off at
> > 20khz, and don't roll off after 20khz like I thought they would, but
> > what about the sample rate? At 44.1kHz doesn't that mean anything over
> > 22khz is more aliasing or harmonic distortion than an actual recording
> > of bat sounds?
>
> The sounds of those bats that I did record were in the 12kHz to 15kHz
> range. 44.1kHz sample rate is sufficient. I did use two Rode NT1
> microphones, connected to a Tascam DR-70D recorder. If I record the
> ultrasound in the recorder, I use 48kHz sample rate. If live processing
> is required, I connect the Tascam's output to my notebook's audio input,
> which has only 44.1kHz sample rate. That works as well. It is important
> that you disable the low pass filter in the Windows control panel
> (properties of the microphone).
>
> Michael
>
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