The Virtual Soundcard tab allows for a couple tweaks the the Virtual Soundcard configuration. Under ideal conditions, these options should never have to be changed. For more information, see the dedicated Virtual Soundcard page.
Virtual Soundcard Tab(click to enlarge)

Virtual Soundcard Tab (click to enlarge)

Changing the audio capture source

Windows core audio engine loopback (Vista/7 only)

This is the preferred method of audio capture on Windows Vista and Windows 7 systems as no additional configuration is required.

This option is disabled in Windows XP.

Sound card or other audio interface

This is only option available on Windows XP. In the dropdown, choose "Stereo Mix" or a similar recoding input to capture all of the audio being sent to that device. If you have multiple audio adapters, make sure you've chosen the correct one.

On Windows Vista/7 systems, it is occasionally desirable to capture audio from a hardware device. If you're using a low-performance PC and getting an unacceptable amount of audio glitching, try to alleviate the problem by setting Jamcast to capture from your soundcard instead.

Capture buffer size

Sets the maximum amount of audio data, in seconds, that Jamcast will buffer. When the capture buffer is full, Jamcast will dump all buffered audio data. Set this to a higher number if the capture buffer is filling up too often; set to a lower number to reduce memory usage. The default of 10 seconds is ideal for most users.