| Hometheaterphile April 2007
 A Conversation
with Tom Dixon of DTS
I am an early adopter of both of the new high-definition
disc formats. I bought an HD DVD player as soon as the first model hit the shelves,
and I recently bought a Sony PlayStation 3 to allow me to watch Blu-ray discs. Both
formats are advances on the DVD experience -- in fact, both are such big advances
that my cinema attendance has decreased quite a bit. Why pay $8 for a movie plus $10 for
snacks when I can enjoy the film at home? My home-theater system can’t compete with a
cinema’s sheer visual scale, but as far as sound is concerned, my system wins
hands down.
This is because the new HD formats improve the quality of
the audio as much as the video. New sound formats -- such as Dolby Digital Plus, which
triples the bit rate of the average standard-definition Dolby Digital 5.1 soundtrack --
are included on almost every HD release. This increase in sound information results in a
soundstage that’s bigger, more detailed, and more dynamic. I was blown away by the
first film I saw on HD DVD, The Fast and the Furious 2. The video was so crisp
and clean, and the audio was explosive in a way I hadn’t before experienced in my
home. Now, as HD DVD and Blu-ray continue to duke it out in the marketplace and more
and more hi-def titles are released, some of them boast soundtracks that claim to be
"bit for bit" identical to the studio masters, which should bring the aural
experience up to par with the visual.
One of the new sound formats is DTS-HD Master Audio (DTS-HD
MA). Dozens of HD titles have been released with soundtracks in this format, but so far,
no player is capable of decoding DTS-HD MA. Through downloads, both of my HD players
should eventually be able to be upgraded to decode it. Meanwhile, I took some time to try
to understand how DTS-HD MA works. In an exchange of e-mails I interviewed Tom Dixon,
director of strategic marketing for DTS, Inc. Dixon, a home-theater enthusiast, has 22
years’ experience in consumer-electronics marketing and sales and, like me, is an
early adopter of both HD DVD and Blu-ray.
Randall Smith: I have always preferred a DTS
soundtrack over a Dolby Digital 5.1 soundtrack; I have always felt the DTS track was more
dynamic and more detailed. I have also noticed that a DTS track is usually a few dB louder
than the Dolby track. Is this a deliberate characteristic of a DTS mix, and will this be a
characteristic of the new DTS-HD Master Audio mixes?
Tom Dixon: I am not aware of DTS defaulting at a
higher average dB level than Dolby. The DTS tracks on DVD are decoded at a much higher
transfer rate; there is noticeably better detail and a wider dynamic range -- so the peaks
are louder. This dynamic range will be more pronounced with DTS-HD Master Audio.
RS: DTS-HD MA is claimed to be identical to the
studio master. Does this mean it is identical to the theater mix, or to the mix created
for the DVD?
TD: DTS-HD Master Audio is identical to the
soundtrack mixed and created for Blu-ray Disc or HD DVD. The DTS codecs for
feature films and home video are different. Also, the actual mixes are different. For
cinema, the goal is to deliver surround sound to a lot of people in a big room. In home
theater, the goal is to deliver an immersive surround mix to a few people in a small area.
RS: So the DTS-HD MA track is specially created
only for the new HD formats?
TD: Well, not quite. DTS-HD Master Audio was
designed to the audio specifications of the Blu-ray and HD DVD formats. It has
performance capabilities that actually go beyond the spec. For example, the codec is
capable of 24-bit/384kHz audio.
RS: How is the mixing process of creating a
DTS-HD MA track different from creating a standard-definition DTS track?
TD: DTS-HD is a one-stream system, and contains both
the DTS Digital Surround Core plus a DTS-HD Extension. So a content creator would look at
the space (or bit budget) available for audio tracks. From there they would decide what,
if any, compression would be needed at all to make it fit on the disc. If they have the
bit budget for DTS-HD Master Audio, the content would be encoded with a completely
variable bit rate. If the bit budget is not there to do lossless, then the content creator
would pick the highest constant bit rate (say, 3.4Mbps) and encode in DTS-HD
high-resolution audio. There would be compression (or data lost), but only in a few peaks.
RS: What will be the average bit rate for DTS-HD
MA?
TD: It depends on the content. The greater the bit
depth (24 bit vs. 16 bit), the higher the sampling frequency (96kHz vs. 48kHz), and the
greater number of channels (7.1 vs. 5.1), and the amount of information going to each
channel can raise the average and peak bit rates considerably. For most of the movies, we
have been averaging around 2.8-3.0Mbps with peaks around 4.0Mbps. By comparison, a music
feature recorded in 24/96 in 7.1 with heavy channel information to all channels had an
average bit rate of 6.0Mbps and peak bit rates at 12.0Mbps. For the DTS Core, it would be
encoded at the full constant bit rate of 1.5Mbps. So if a consumer does not have a new
receiver with DTS-HD Master Audio, they could still play back the DTS Core on their
existing receiver at a pretty high transfer rate.
RS: Do you think the ability to use DTS-HD MA in
the home will encourage mixing artists to create even more dynamic and detailed
soundtracks for movies being filmed today?
TD: Yes. The mixing artist and content creators love
the new format. Both music and soundtrack artists love the expanded mix that can be
created with 7.1 channels. You will see composers and recording artists creating work
specifically designed for 7.1 high-definition audio playback.
RS: With DTS-HD MA soundtracks already present on
many Blu-ray DVDs, why hasn’t a decoder been developed for download to Blu-ray
players? When will a decoder be available?
TD: The classical approach is for the player to pass
through the uncompressed codec to the A/V receiver for decoding. This was the connection
model that worked well with the first generation of digital home theater (DVD). However,
the delays in HDMI 1.3 have pushed this model out a bit. Just as in the first iteration of
standard DVD players, we expect to see a number of first- and second-generation
high-definition players with onboard DTS-HD Master Audio decoders. Some of these players
may be upgraded through download, and some will have the decoders at launch. Due to
confidentiality issues, we cannot disclose the brands or launch timings.
RS: With DTS-HD MA, it seems that the consumer
will be able to achieve the best possible soundtrack available for their home theater.
What’s next for DTS?
TD: The DTS-HD Codec Extension is an extremely rich
technology. It actually has performance and flexibility features beyond the applications
for Blu-ray and HD DVD. Also, the core DTS codec has a significant quality advantage
over other surround formats. As DTS expands into new forms of digital entertainment
distribution, there is a great opportunity to leverage this quality into emerging products
and services. The sky’s the limit.
RS: So far, I have seen mainly Blu-ray titles
with DTS-HD MA soundtracks. Will that trend continue?
TD: Well, we also have a good number of titles on HD
DVD. However, we expect to see DTS-HD Master Audio prevalent on new releases on both
formats. Consumers are captivated by the idea of having audio that is "identical to
the studio master," and the content providers see the obvious value proposition. The
content providers love the fact that the DTS-HD system takes up less space on the disc
than the lossless and legacy streams of competitive formats. They also like the fact that
DTS-HD Master Audio contains the DTS Digital Surround Core, which is compatible with all
of the legacy DTS decoders in the marketplace. It’s a "no-brainer" for them
to include DTS-HD Master Audio.
RS: What are the main differences between DTS-HD
MA and Dolby TrueHD?
TD: There are three key advantages to DTS-HD Master
Audio. First, DTS-HD Master Audio contains the DTS Digital Surround Core, which is
completely compatible with all of the 65-million-plus DTS-featured legacy home-theater
systems. Consumers playing back their audio through an existing receiver can experience
surround sound at a 1.5Mbps data rate -- two-and-a-half times what the other format’s
legacy codec can do. Consumers can go buy Blu-ray and HD DVD movies with DTS-HD
Master Audio and experience an immediate audio improvement with their existing system.
Second, DTS-HD Master Audio is capable of 7.1-channel
speaker remapping. Right now, there is not an agreed-upon industry standard of where to
place speakers in a 7.1 setup. It is possible for content creators to mix to one type of
speaker layout that may not match the end consumer’s layout. With DTS-HD MA, the
decoder can remap to seven different layout schemes. This will allow the consumer to get
the best possible translation of the original mix.
Third, DTS-HD and the DTS Digital Surround Core are on a
single bitstream. To deliver a lossless and legacy encode, the other format must use
separate streams. A DTS-HD Master Audio encode takes up less space on the disc compared to
a Dolby TrueHD and Dolby Digital encode.
RS: Will DTS-HD MA filter down to video games for
the PlayStation 3 and Xbox 360?
TD: Yes. Gamers have always pushed the industry to
deliver the most realistic and immersive gaming experience possible. With gaming now in
high-definition, we believe DTS-HD Master Audio will complete the experience. With 7.1
channels of essentially perfect sound, game developers can now explore the audio sensory
domain like never before.
RS: Are there big movie titles waiting in the
wings to be re-released in the new HD formats once DTS-HD MA becomes a reality? Can you
give us some titles?
TD: Yes. We expect to see the number of titles grow.
However, we cannot disclose the information.
RS: Thanks again. Any closing thoughts?
TD: Both the Blu-ray and HD DVD formats are
incredible products that are going to take home theater to a whole new level. But
consumers need to remember to upgrade their audio. Our consumer research indicates that
nearly all high-definition TV owners rate high-quality multichannel sound as one of the
most important aspects of the hi-def experience. However, only 70% of HDTV owners have
multichannel surround sound! Thirty percent are experiencing high-definition out of the
little peanut speakers in the TV. We consider this a tragedy. For this reason, we have
created a series of one-minute educational videos that highlight the benefits of
high-definition audio. We plan to broadcast these videos into the high-definition retail
satellite networks at Best Buy and Circuit City this year. Consumers looking to purchase a
high-definition plasma or LCD display will see these videos at the point of sale, and
hopefully upgrade their systems to include a new home-theater surround system.
...Randall Smith
randalls@hometheatersound.com |
