When watching web pages with embedded Flash video or animation such as movie or video clip on YouTube and MySpace using Mac OS X, users may hear no sound. The no sound audio output problem happens despite video playback is fine, and the issue can happen on any web browser, i.e. Safari and Mozilla Firefox. Strange thing is that, when using other applications such as RealPlayer, QuickTime Player and VLC Player, the sound is played properly. And no audio output issue does not affect embedded QuickTime including HD contents on the web.
Apple Mac OS X support site
explains (link dead) that the no audio from certain multimedia content issue is caused by some audio applications that change the computer’s audio settings to a sample rate that is too high for other applications to use. The notorious programs include certain versions of Real Player, VLC Player and Audacity.
The solution to solve the Internet movie no sound or audio output is to reset the audio setting in Mac OS X to original configuration:
- Open “Audio MIDI Setup” (/Applications/Utilities/), then check the “Audio Output” setting.
- Change the “Audio Output” setting to 44100.0 Hz.
- Quit Audio MIDI Setup.
If the Audio Output setting is grayed out or disabled, go to “Properties For” tab in Audio MIDI Setup, and select “Built in Output”.