Mac to RCA to TV

[mecinus20]

I have my Macbook pro hooked up to my RCA hdmi surround sound system using a mini displayport to HDMI cable. The RCA is hooked up to the TV, so all of the video inputs run through the surround sound system to the TV. I'm having trouble getting surround sound while my laptop is plugged in. it either plays on my computer's speakers or not at all.

 

[jFiveNYC]

What year is your MBP?

From: https/en.wikipedia.org/wiki/Mini_displayport#Compatibility

While the DisplayPort specification is capable of supporting digital audio, the older 2009 line of MacBooks and MacBook Pros are unable to provide an audio signal through the Mini DisplayPort, and only do so over USB, Firewire, or the audio line out port instead (the April 2010 line of MacBook Pro, and late-2009 iMac and later, however, supports this[15]). This can present a problem to users who intend to connect their computers to HDTVs using a Mini DisplayPort to HDMI adapter. To work around this issue, some third-party manufacturers have created dual or triple headed adapters that get power for the adapter from a USB port, video from the Mini DisplayPort, and audio from either the USB port or the optical out port. Either option terminates with a single female HDMI connector, thus allowing both video and audio to be channeled over the one HDMI cable.[16]