Can Optical Cable Transmit Dolby Atmos?

The short answer to whether optical cable can transmit Dolby Atmos is no, but let's delve into the technical details to fully understand why.

Understanding Dolby Atmos

Dolby Atmos is a surround sound technology that provides an immersive audio experience, featuring dynamic audio objects that can move in three-dimensional space. There are two versions of Atmos: uncompressed and compressed. The uncompressed version is typically found on Blu-ray UHD discs, while the compressed version is used in broadcast and streaming, carried as Dolby Digital Plus (DD ).

Technical Limitations of Optical Cable

Optical Cable (Toslink):

Developed in 1983, accompanying the CD technology. Limited bandwidth to 384Kbps. Supports Dolby Digital but not more complex audio formats or Dolby Atmos. Best suited for 5.1 and 6.1 channels.

HDCP Restrictions:

HD Content Protection (HDCP) blocks Dolby Digital signals from being transmitted except over HDMI. This is why optical cable is restricted in its use for high-definition audio.

Why HDMI is Required for Dolby Atmos

To efficiently transmit the more complex Dolby Atmos format, an enhanced HDMI connection such as eARC (Enhanced Audio Return Channel) is required.

eARC:

Enhanced bandwidth of 37 Mbps, supporting up to 32 channels. Adequate for transmitting and processing Dolby Atmos signals. Typically found on modern high-end TVs and soundbars.

Popular Examples of eARC Supporting Equipment

For instance, the Sonos Arc soundbar, which comes with an eARC connection and supports Dolby Atmos. Despite this, it is important to note that the Arc is also equipped with an optical audio adapter for compatibility with TVs that do not have an eARC connection.

However, using the optical adapter means the Dolby Atmos signal is downgraded to merely Dolby Digital. While this still offers a high-quality musical experience, it does not reproduce the full spatial distribution of sound that Dolby Atmos is capable of.

Conclusion

While an optical cable can transmit Dolby Digital audio, it is not designed to handle the more complex and bandwidth-intensive Dolby Atmos format. For best results, devices with HDMI eARC should be used to ensure full support for Dolby Atmos.