DTS-HD Master Audio: What You Need To Know

Taking surround sound up a notch

DTS-HD Master Audio Logo
Image provided by DTS

DTS-HD Master Audio is a high definition digital surround sound encoding format developed by DTS for home theater use.

This format supports up to 8-channels of surround sound with increased dynamic range, wider frequency response and higher sampling rate than other DTS surround formats. Its closest competitor is Dolby TrueHD.

Similar to Dolby TrueHD, DTS-HD Master Audio is primarily employed in the Blu-ray Disc and Ultra HD Blu-ray formats and has been used in the now-discontinued HD-DVD format.

Accessing DTS-HD Master Audio

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

  • Transfer the encoded bitstream, that is compressed, via HDMI (ver 1.3 or later) connected to a home theater receiver with a built-in DTS-HD Master Audio decoder. Once decoded, the receiver passes the signal through the amplifiers, to the designated speakers.
  • Designate that the Blu-ray Disc/Ultra HD Blu-ray player decode the signal internally (if the player provides this option). The decoded signal is passed directly to a home theater receiver as a PCM signal via HDMI, or, via a set of 5.1/7.1 channel analog audio connections. In this case, the receiver does not need to perform any additional decoding or processing – It just passes the already-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 may only provide internal two-channel decoding, rather than full 5.1 or 7.1 channel decoding capability.

If you use the internal decoding to analog audio connection option, the Blu-ray/Ultra HD player has to have a set of 5.1/7.1 channel analog audio outputs, and the home theater receiver has to have a set of 5.1/7.1 channel analog audio inputs, both of which are now very rare.

Unlike the core, DTS surround sound format, DTS-HD Master Audio (either un-decoded or decoded) cannot be transferred by Digital Optical or Digital Coaxial audio connections. The reason for this is that there is too much information, even in compressed form, for those connection options to accommodate the DTS-HD Master Audio signal information.

Digging A Little Deeper

When DTS-HD Master audio encoding is employed, the soundtrack is bit-for-bit identical to the original uncompressed recording. As a result, DTS-HD Master Audio classified as a "Lossless" digital surround sound audio format (a claim also made by Dolby Labs for its own Dolby TrueHD surround sound format).

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

Dolby TrueHD supports a maximum of 18mbps transfer rate on Blu-ray or HD-DVD.

Although DTS-HD Master Audio encoding is capable of providing up to 8-channels of audio (7 full channels and 1 subwoofer channel), it can also be provided as a 5.1-channel or 2 -channel format if preferred by the technician mixing the sound (although the 2-channel option is rarely used).

When employed in association with content on a Blu-ray Disc, the disc may contain either a DTS-HD Master Audio soundtrack or a Dolby TrueHD/Atmos soundtrack, but rarely, if ever, will you find both options on the same disc.

In implementing DTS-HD Master Audio, DTS had the wisdom to make it backward compatible. What this means is that even if you have a Blu-ray or Ultra HD Blu-ray Disc that is encoded with a DTS-HD Master Audio soundtrack, you can still access embedded standard DTS Digital Surround soundtrack if your player or home theater receiver is not DTS-HD Master Audio Compatible. Also, for those home theater receivers that don't have HDMI, you can still access standard DTS digital surround via the digital optical/coaxial connection options.

The DTS-HD High-Resolution Audio Alternative

A variation of DTS-HD Master Audio, which is referred to as DTS-HD High-Resolution Audio (DTS-HD HR) is sometimes used in place of DTS-HD Master Audio. It has a more limited bit-rate (3 to 6mbps), but with 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 may not be enough space to include the full lossless DTS-HD Master audio format due to the inclusion of added video or soundtrack options that may be included on a disc.

In the same manner that 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 should your home theater receiver not have the ability to 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 at those spec levels, you have to have a really good ear, and of course, the capabilities of your home theater receiver, speakers, and even your room acoustics will come into play for the final listening result.

Also, to take things up 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/Ultra HD Blu-ray Discs and a DTS:X-enabled home theater receiver.