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A brief
history of DTS Audio on DVD
Getting
down and dirty...
DTS capability on DVD players is only fairly recent. The vast majority
of players sold to date do not have DTS capability - which is another
problem DTS is going to have in order to become widely accepted.
Originally, DTS planned to encode the DTS signal on a DVD in the same
way they encode it on CD and LD, that is as a multiplexed PCM bitstream
that "looks" to the player like a standard L-PCM track. The initial test
pressings on DVD didn't play quite right on certain decoders like the
Millennium, so Millennium did a quick upgrade to fix the problem (only
the first 300 or so decoders were affected).
Then, the DVD-Video group in charge of the DVD specs told DTS that they
couldn't format the signal like CD and LD because without a decoder, a
consumer would simply hear white-noise if they didn't switch to the alternate
DD or PCM track. It was a good decision, because hearing white-noise without
a decoder is totally unacceptable in a new format. So, DTS was forced
to add a "DTS Flag" to the DTS DVD bitstream so that the player could
identify the type of bitstream present and route it properly.
However, this "broke" compatibility of DTS DVD's with existing players...existing
non-DTS DVD players can't read the flag, and thus, simply 'mute' the bitstream.
Now new players with a DTS-Output and the appropriate recognition circuitry
were required...additionally, DTS had to perfect the DTS DVD mastering
software used to encode the DTS audio onto the DVD MPEG-2 audio transport
stream. This took quite a while with many of the early versions having
'bugs' that prevented them from decoding properly. Also, some DTS decoders,
like the Millennium (and a few others) needed another upgrade to recognize
the slightly 'modified' DTS bitstream. (for the Millennium 2.4.6 decoder,
it was a simple, consumer installed, upgrade of the EPROM and PIC chips)
In the meantime, DTS issued some 'demo' DVD's with the DTS bitstream encoded
"illegally" as a standard 16-bit/48kHz PCM track, so that regular DVD
players could be used to play them back...the only player it dosen't work
on is the Pioneer DVL-700...for reasons unknown!
When the mastering software was perfected, DTS issued the #3 Demo which
was formatted in the final DTS DVD audio spec and required a compatible
DVD player. Anyway, so that's what happened with DTS on DVD. While most
new DVD players are DTS compatible, a shockingly large number of new players
from companies like Sony, are not DTS equipped. That's because DTS is
listed simply as an "option" in the DVD spec and no player is ever required
to be DTS compatible. Since the necessary circuitry costs basically nothing
to add to a DVD player (other than the DTS per-unit licensing fee - DTS
DVD's, CD's and LD's have a similar per- disc fee of $1 dollar), DTS should
attempt to get the format listed as a "mandatory" decoding standard so
that all new players would be required to recognize it. Of course, they
might have tried already. Because the DTS capability is contained in the
DVD players chips, it's not possible to upgrade an older player to be
DTS compatible...well, it might be, but it wouldn't be worth the cost.
BTW, the 'main' encoding standard for DTS on DVD runs at 1.5mb/s, but
other, lower rates, are possible, such as 700kb/s, etc. DTS on CD and
LD runs at 1.2mb/s (NOT 1.4 as is commonly believed). For DVD-Video, DTS
can't be encoded at any rate higher than 1.5mb/s, just as AC-3 is limited
to 448kb/s max on DVD. (Sony is allocated a max of 1.2mb/s for ATRAC*Pro-SDDS
encoding on DVD - not that they'll ever use it though!) DTS on DVD uses
a 48kHz sampling rate (required by the DVD spec) and on CD/LD uses 44.1kHz.
So, on DVD, DTS can have slightly better high-frequency response.
Did I miss something?
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