DTS-HD Master Audio: What You Need to Know

Taking surround sound up a notch

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.

The internal decoding to analog audio option requires a Blu-ray or Ultra HD Blu-ray player with a set of 5.1/7.1 channel analog audio outputs. The home theater receiver must have a set of corresponding 5.1/7.1 channel analog audio inputs. Both options are now rare.

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).

Dolby TrueHD supports up to an 18 Mbps transfer rate on Blu-ray or HD-DVD.

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).

When used with Blu-ray Disc content, either a DTS-HD Master Audio soundtrack or a Dolby TrueHD/Atmos soundtrack may be included. You'll rarely find both options on the same disc.

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.

DTS-HD HR occupies a similar position as Dolby Digital Plus does in relation to Dolby Digital and Dolby TrueHD.

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.

To take things further, DTS also offers the DTS:X format, which adds more immersion than DTS-HD Master Audio. The format can be accessed from properly-encoded Blu-ray and Ultra HD Blu-ray discs and a DTS:X-enabled home theater receiver.

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