DTS-HD Master Audio: What You Need to Know

DTS-HD Master Audio is a high-definition digital surround sound format developed by DTS for home theater use. The format supports up to eight channels of surround sound with an increased dynamic range, a wider frequency response, and a higher sampling rate than other DTS surround formats. Its closest competitor is Dolby TrueHD.

Similar to Dolby TrueHD, DTS-HD Master Audio is primarily used in the Blu-ray Disc and Ultra HD Blu-ray formats. It was also used in the discontinued HD-DVD format.

How to Access DTS-HD Master Audio

A DTS-HD Master Audio signal can be transferred from a compatible source (such as Blu-ray and Ultra HD Blu-ray) in two ways:

• Through a DTS-HD Master Audio encoded bitstream, using HDMI (ver 1.3 or later), to a home theater receiver with a DTS-HD Master Audio decoder. The receiver decodes the signal and passes it through its amplifiers to the speakers.
• Through a Blu-ray Disc or Ultra HD Blu-ray player to decode a DTS-HD Master Audio signal internally (if the player has the option). The decoded signal passes to a home theater receiver as a PCM signal using HDMI or a set of 5.1/7.1 channel analog audio connections. The receiver doesn't need to perform additional decoding or processing. It passes the decoded audio signal to the amplifiers and speakers. Not all Blu-ray Disc players provide the same DTS-HD Master Audio internal decoding options. Some only provide two-channel decoding, rather than 5.1 or 7.1 channel decoding.

Unlike the DTS Digital Surround format, DTS-HD Master Audio (either un-decoded or decoded) can't be transferred by digital optical or digital coaxial audio connections. There is too much information, even in compressed form, for those connection options to pass DTS-HD Master Audio signals.

Digging a Little Deeper

With DTS-HD Master audio encoding, the soundtrack is bit-for-bit identical to the original uncompressed recording. As a result, DTS-HD Master Audio is classified as a lossless audio format (a claim also made by Dolby Labs for Dolby TrueHD).

The sampling frequency for DTS-HD Master Audio is 96 kHz at 24-bit depth. The format supports transfer rates on Blu-ray of up 24.5 Mbps and 18 Mbps for HD-DVD (for those that still have HD-DVD discs and players).

Although DTS-HD Master Audio can provide up to eight channels of audio (seven full channels and one subwoofer channel), it can also provide a 5.1-channel or 2-channel format (although the 2-channel option is rarely used).

DTS-HD Master Audio is backward-compatible. So, if you have a Blu-ray or Ultra HD Blu-ray disc encoded with a DTS-HD Master Audio soundtrack, you can access a standard DTS Digital Surround soundtrack if your player or home theater receiver isn't DTS-HD Master Audio compatible. Also, if your home theater receiver doesn't have HDMI, you can access standard DTS digital surround using the digital optical or coaxial connections.

The DTS-HD High-Resolution Audio Alternative

A variation of DTS-HD Master Audio, DTS-HD High-Resolution Audio (DTS-HD HR) is sometimes used in place of DTS-HD Master Audio. It has a limited bit rate (3 to 6 Mbps) and the same bit depth and sampling rate as DTS-HD Master Audio. It can be used for Blu-ray or Ultra HD Blu-ray Disc applications when there isn't enough space for lossless DTS-HD Master Audio due to the inclusion of added video or soundtrack options included on a disc.

Just as DTS-HD Master Audio is built on top of the DTS core, so is DTS-HD HR, making it backward compatible with other DTS surround sound formats if your home theater receiver can't decode the DTS-HD High-Resolution format.

The Bottom Line

Can you hear the difference between DTS-HD Master Audio and Dolby TrueHD? Maybe, but you need a really good ear to tell. Also, the capabilities of the home theater receiver, speakers, and room acoustics come into play for the final listening result.