Unwanted silence recording with WASAPI

A recent change (last few weeks) makes WASAPI start recording immediately, instead of waiting for the music input to start. Might be related to the improvement “can now record leading silence on mp3s”? Or maybe due to a Windows10 upgrade? (Audacity Prefs Recording - Sound Activated Recording is OFF)

Audacity Preferences: Device WASAPI (PortAudio V19.5.0), Playback Speakers, Recording Speakers(loopback)

Problem appeared on new Lenovo X1 Extreme since purchase a month ago, won’t wait for music input:

  • Windows 10 Home 1909 Build 18363.657 64bit
  • Audacity 2.3.3 Build 15 Nov 2019 Commit ID 008d8d

Problem has not yet appeared on old HP Elitebook 8560p, still waits for input before recording:

  • Windows 10 Pro 1909 Build 18363.592 64bit
  • Audacity 2.3.3 Build 15 Nov 2019 Commit ID 008d8d

This is a major inconvenience. One needs to set the recording ready, then fix up the source and start the input, knowing WASAPI will automatically record, and stop when the source finishes.


You can try [u]Sound Activated Recording[/u].

I’d guess where it’s recording you’ve got some silent audio “playing” and the other case you’ve got "nothing’.

…Most people have the opposite complaint. The don’t want to stop when the audio stream pauses/stops. :wink:

“Unwanted audio” suggestion is welcome, but alas is not the cause. (Recorded waveform is completely flat, even at high magnification.

I omitted another fact. Before the change, WASAPI recorded the captured audio stream at a constant volume level, regardless of the playback volume set on the PC. I could record with the volume turned right off, in silence watching the waveform being generated - presumably direct from the sound card.

Since the change (on the Lenovo), WASAPI records exactly what is actually being heard from the PC speakers - if I change the volume, the recorded waveform gets bigger or smaller.

This presumably means WASAPI is capturing the analog signal to the speakers (or headphones) and reconverting it back to digital, with loss of quality! Perhaps another effort by BrainSoft to prevent accurate copying (and protect copyright)?


If due to Windows, this problem probably arises from Update KB452695, an optional update installed on my Lenovo PC but not HP PC.

Windows 10 Version 10.0.18363 Build 18363 Audacity 2.3.3

Audacity’s failure to pause and wait for music to start (recording with WASAPI interface) appears to have been rectified by a Windows update in the last 2 months. Now functions as originally: recording starts when signal input is received, stops soon after signal ends.

The other problem remains: Audacity is not recording direct from the sound card, but actually from the feed to the built-in loudspeakers. When the monitor playback volume is adjusted, so is the recording signal input.