Recording system audio is a tricky business invovling several components and steps which all must be configured and work properly for system audio to record correctly. When one of these steps or settings isn't set correctly, it can be difficult to figure out why the system audio in saved movies is silent, or why one program's audio isn't being recorded while others are. Read this page to learn about troubleshooting problems with system audio recording in Screenflick.
Screenflick uses a kernel extension called Soundflower to record system audio on your Mac. Soundflower is an open source extension used by several other screen recording and audio recording programs. What Soundflower does is create a "virtual" audio device, which has input and output streams. To record system audio with Soundflower, the system-wide default audio output device is set to Soundflower. This directs all audio into Soundflower's input. Any program can then record from Soundflower's output, which effectively records the system audio.
When you start a recording with system audio, Screenflick switches the system audio output device to "Soundflower (2ch)" which Screenflick then uses as an input to record from. Some programs will play over a specific output device rather than always using the current system setting which can lead to problems like this.
It's likely that when you launch the program, it sees that your speakers are the current output device and then internally sets itself to play over those speakers. Then when you start recording with Screenflick, Screenflick changes the system output device setting to the Soundflower. The program however, may not be watching for the notification that the system output device has changed and will still be playing audio directly to the speakers instead of the Soundflower like it should be.
The result of this happening, is that while you can hear all audio correctly over your speakers while the recording is taking place, Soundflower (and thus Screenflick) is not being fed audio from the troublesome program, which creates a movie with missing audio. This can lead to the confusion that it is Screenflick which is failing to record audio, when it is really is really the program playing the audio which is causing the problem.
What needs to happen is the program playing audio needs to launch after the system output device has already been changed to Soundflower. There are two ways this can happen.
The key thing is that the default system output must be set to Soundflower before the program starts up and plays audio.
There is also a third possibility. In some programs (such as Skype and other programs which focus on audio) there is a preference to specify which audio device to direct audio to. If the program you're recording has one of these settings, you can simply set that setting to "Soundflower (2ch)" when you're making Screenflick recordings.
Although this shouldn't happen, the most likely cause is Soundflower is still selected as the system audio output device. To fix this, simply go into the Audio panel in System Preferences and select your speakers in the device list in the Output tab.