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Why won’t my older DVD player play DTS DVDs? | MDCT Time to Frequency Conversion |
The DVD DTS flag was not established until Nov 1998. This flag must be inserted into the DVD’s digital coax or optical output for the receiver to recognize and decode DTS. Therefore DVD units that are not marked “DTS ready” will not play DTS even though they have digital outputs.
Can DVD movies contain both DTS and AC-3 audio tracks?
Yes they can. Currently the DVD audio choices are:
·PCM – Producing the conventional analog L/R sound
·Dolby Digital or
·DTS – Compressed 5.1 channel surround sound
How does DTS work?
The DTS and
The general encoding of the DTS compression system will be explained. DTS has four blocks used to compress the PCM input audio into a single bit stream:
PCM audio 
Time to
6 Channels |
| Frequency |
| Compression |
|
|
Conversion
6 lines
DTS
Multiplexer |
| Packer |
| Compressed |
|
|
Bit Stream
Sync 
Each single channel PCM source signal is grouped and allocated to one of 32 frequency bands for analysis. The process is commonly known as Modified Discrete Cosine Transformation (MDTC). This frequency band allocation allows for identification and removal of redundancy among the channels in the next compression stage.
Coefficients
6
C H A N N E L S
Frequency
Coefficients
Frequency
Compression
Adaptive Predictive Coding (ADPCM)
ADPCM involves smaller support stages to:
·Combine the same sounds found in other channels,
·Remove undetectable audio levels (below human hearing thresholds),
·Remove short interval noises that are swamped by louder sounds (psycho acoustic masking); and
·Remove transient noises that do not repeat on the same or other channels.
The support stages include transient, vector and prediction analysis stages to determine if the sound is short term, increasing or decreasing, and if the sound will repeat. Removal or the combination of sounds (compres- sion) is determined by the analysis.