What is DTS-HD and DTS-HD Master Audio?
When Blu-ray hit the scene and snuffed out (outspent, really) HD-DVD in the mini format war, a new audio CODEC was needed to handle the many ways in which audio would need to be delivered in the high-definition era. DTS-HD Master Audio (formerly known as DTS++) became the new defacto-standard for the premium level of on-disc HD audio. DTS-HD Master Audio is a “lossless” audio format—using a variable bit-rate technology to deliver high-quality audio while keeping file sizes small and conserving bandwidth. It turns out the format was an impressive jump over prior iterations of DTS and was light-years ahead in how it could communicate and transmit the required 7.1 sound for Blu-ray.
DTS (the company) set out to make DTS-HD Master Audio the audible equivalent of listening to the master recordings. Technically speaking, DTS-HD Master Audio carries within its file, two data streams: the original DTS “core” stream and another stream that contains the “residual” data that is made up of what’s left from the original signal and the lossy compressed stream. The decoder is then able to use both to recreate an audio stream that is bit-for-bit identical to the original (i.e. “lossless”). The encoding process is also very quick, and can be done in a single pass—something that is very important in the area of content creation and mastering.
Since DTS-HD Master Audio is essentially bit-for-bit identical to the studio master, it can also be used as an archival format, but while taking up dramatically less storage volume when compared to uncompressed PCM audio tracks.
With respect to the Blu-ray format, DTS-HD Master Audio is becoming popular as it offers significant space-savings, allowing for multiple languages to be stored on a single Blu-ray movie disc. This leaves more room for higher video quality, additional extras, and special features.
DTS is also completely backward-compatible, but in a way that allows legacy AV receivers and other products to playback DTS-HD Master Audio files at up to 1.5 Mbps with up to 7.1 discrete channels at 96 kHz or 5.1 channels at 192 kHz. Here’s what the various bit rates for DTS technologies look like:
Note that DTS-HD can output audio at up to 96 kHz sampling rates, but DTS-HD Master Audio can output 5.1 at up to 192 kHz. DTS-HD Master Audio also has a dramatic range where it can be encoded at a variable rate below 1 Mbps all the way up to around 24.5 Mbps. This is a flexible Mastering-level audio CODEC that has a lot of room for expansion and seems perfectly fit for all but the most aggressive surround formats of the future.
Do you notice the CODECs present on your Blu-ray discs? Ever purposefully select one over another when playing back a movie? Let us know if you have, and why on our Facebook page or leave a comment below.