Can You Use Your Mac as a Surround Decoder?

Are you tired of having to use separate devices for surround sound playback? With the advancements in technology, it's now possible to use your Mac as a surround decoder. In this article, we'll explore how digital consumer surround sound works and provide a step-by-step guide on setting up a multi-channel sound card.

How Digital Consumer Surround Sound Works

Digital surround sound is a clever hack of the existing S/PDIF standard that only supported uncompressed stereo audio. The compressed stream is transmitted as if it were a regular stereo stream, making it possible to decode and play back 5.1 surround sound on devices that don't have built-in surround capabilities.

The most popular standards for encoding 5.1 audio in a bitstream of 1.5 Mbit or less are Dolby Digital (AC3) and DTS. A decoder that recognizes these encodings can decode the compressed data and output the six channels of raw audio to analog outputs, such as RCA or XLR connectors.

Setting Up a Multi-Channel Sound Card: The Procedure

To set up a multi-channel sound card on your Mac, you'll need to force your media player to pass through the encoded stream without altering it. You can do this by setting the volume to 100% and ensuring that the outgoing audio is not altered by any volume control or other device.

There are two ways to get surround sound out of your Mac: decoding the surround stream on the computer itself and sending the six channels of raw audio to a dumb sound card, or using an external decoder that recognizes the encoding and outputs the decoded audio to analog outputs.

Multichannel Output versus Pass-Through

The first method involves decoding the surround stream on the computer itself and sending the six channels of raw audio to a dumb sound card like the CM6206. This method is more straightforward, but it requires a computer with built-in surround capabilities.

The second method uses an external decoder that recognizes the encoding and outputs the decoded audio to analog outputs. This method is more flexible, as you can use any device with multiple analog output channels, such as an amplifier or a home theater receiver.

In conclusion, using your Mac as a surround decoder is possible with the right setup and equipment. By following these steps, you can enjoy high-quality surround sound playback on your Mac without having to use separate devices.

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