Yes, pavucontrol.
We should be able to set our desired sample rate in Audacity, then let PulseAudio handle the sample rates automagically.
Assuming that you have it installed:
- Open Audacity
- Select “pulse” as the recording input
- Click on the recording meter. By default this should start monitoring the default capture device, which is probably your microphone.
- Open PulseAudio Volume Control
- Look in the “Recording” tab of pavucontrol - you should see Audacity listed.
- Click on the “ALSA capture from:” box and select the “Monitor” option.
- Close pavucontrol
- Click on the Audacity recording meter to stop monitoring.
- Start playing a YouTube video.
- Click on the recording meter. You should see it responding to the audio that is playing in YouTube.
- Stop the YouTube video - the Audacity recording meter should show absolute silence.
If that all worked, you should be ready to go.
- Press the Record button in Audacity
- Start the video playing.
There are more detailed instructions with pictures for Ubuntu 10 : http://wiki.audacityteam.org/wiki/Stereo_mix_with_Ubuntu_10