DTS

DTS - SPDIF - Multichannel Audio CD

DTS stands for Digital Theater Systems. While Dolby Digital is the standard 5.1 digital surround format on all DVD players, DTS is becoming a possible alternative. DTS, first introduced in the movie Jurassic Park, is now found on many film soundtracks. DTS soundtracks have been available on laserdiscs for the past couple of years, but we're only starting to see DVD titles with a DTS soundtrack. There are only about a dozen DVD movies with DTS now, but you can expect this number to grow. And there are quite a few CD titles that are DTS-encoded, from Mozart to Marvin Gaye. Buying a DVD player that's DTS-compatible shouldn't cost all that much more and could mean higher sound quality down the road. "DTS compatible" means that the DVD Player will pass a DTS 5.1 surround sound (audio) signal to a DTS decoder for proper playback of DVDs encoded with a DTS soundtrack.

DTS Audio CD or 5.1 Music Disc is an audio Compact Disc that contains music surround sound configurations. The specification permits discrete channel configurations  - 2.0 (L, R) to 6.1 (L, R, C, LFE, Ls, Rs, Cs), although 5.1 (L, R, C, LFE, Ls, Rs. Physically, a DTS Audio CD conforms to the Red Book standard; however a DTS bitstream, is actually encapsulated in each PCM audio track. This configuration permits any non-DTS enabled player to output multi-channel audio when connected to an external DTS-compliant processor (e.g. a typical AV receiver) via a digital interface like S/PDIF or HDMI, provided that the player does not modify the bitstream internally. 

Although the DTS audio track is read at the same fixed bitrate as 16-bit linear PCM (1,411 kbit/s) only 14 bits (1,234 kbit/s) are used for the encoded data stream; the remaining two bits are always zeros. This has the effect of attenuating the noise that would result (by roughly 12 dB) should one attempt to play a DTS Music Disc with a non-DTS system, and thereby reducing the chance of speaker damage. However this is a non-issue for players with internal DTS decoders, such as some DVD-Audio and Blu-ray players; these devices will output a properly decoded audio signal through their analogue ports. 

Although all compliant DTS decoders support surround configurations of up to 5.1 channels, a DTS ES decoder must be used to fully decode discs with 6.0 or 6.1 channels of audio. DTS ES comes in two flavors: DTS ES Matrix and DTS ES Discrete. Depending on the disc and decoder used the Cs (center surround) channel will either be derived from the Ls and Rs of a conventional 5.1 track via matrix decoding, or exist as a fully discrete digital extension to a 5.0 or 5.1 core. In either case, backward compatibility is maintained with non-ES decoders.

About SPDIF

SPDIF (Sony/Phillips Digital Interconnect Format) - digital audio interface. SPDIF was first used only to transmit stereo 16-bit PCM data (CD player was the only source of digital audio). It is very straightforward: audio samples are transmitted at constant frequency, one-by-one (and bit-by-bit) in 32-bit blocks where 8 bits are used for synchronization and some side info and 24 bits are used for sample. In most cases, only 16-bit transmission is supported (CD carries only 16-bit sound) and low 8 bits of a sample are always zeroed. This interface is very simple and cheap and so it became widespread.

Therefore, when multi-channel sound era came to home theaters, SPDIF was an ideal candidate for digital interface to transmit multi-channel sound. However, it is a problem: current interface implementations work only with stereo sound, but now it is required to transmit up to 6 channels (or 8 channels at present). It was decided not to change the interface but to transmit compressed multi-channel sound instead of PCM data (for digital interface it does not matter what to transmit). So receiver must recognize compressed data and decode it. For this purpose a new standard was introduced (IEC 61937) that describes how compressed data must be transmitted and how receivers can distinguish PCM and compressed data.

So SPDIF interface has two modes:

     PCM data transmission mode and

     Compressed data transmission mode.

Unless noted we well use SPDIF transmission, SPDIF output mode and SPDIF stream terms only for encoded streams afterwards.

 multi-channel AudioCD

Compressed data may be transmitted over SPDIF instead of PCM data. Therefore, we can prepare a CD disk and place compressed AC3 or DTS data instead of usual PCM tracks. When we playback this disk with a CD player connected to a receiver we will get true multi-channel sound!

But this trick does not work with analog connection and portable CD players: we will get terribly loud noise instead of nice music. Because of this CD disks with AC3/DTS tracks are relatively rare.When a media player tries to playback a multi-channel disk it does not know that it contains compressed data. It's just because it is no simple method to distinguish usual and multi-channel disks. We have to read some data from the disk and have some method to know what kind of data we got. Hardware receivers have a special detection circuit, but software media players (most of it) have no. That's the point why media player cannot playback such discs right even when some AC3 or DTS decoder is installed.

DTS CDs are encoded in 5.1 surround sound using the DTS compression algorithm. As such, the fidelity is of lower quality than the sound quality offered by CDs, DVD-Audio discs, and SACDs. DTS CDs are not encoded in stereo. We can play DTS CDs in three ways:

- On a CD player connected to a 5.1-channel receiver or pre/pro with a DTS decoder via an optical or coaxial digital cable.
- On a DVD-Video player with the "DTS Digital Out" logo on the front panel (meaning any player available today) to a 5.1-channel receiver or pre/pro with a DTS decoder via an optical or coaxial digital cable.

- On a DVD-Video player with a built-in DTS decoder connected to a 5.1-channel receiver or pre/pro via the 5.1-channel outputs (i.e., six RCA cables).

SONY DVD COMBO Players:

DAV-DZ640K,     DAV-DZ340K,     DAV-TZ215