Formatos DTS

Formatos DTS e Codec

On the consumer level, DTS is the oft-used shorthand for the DTS Coherent Acoustics codec, transportable through S/PDIF and used on DVDs, CD-DAs, LDs, and in wave files. This system is the consumer version of the DTS standard, using a similar codec without needing separate DTS CD-ROM media. Both music and movie DVDs allow delivery of DTS audio tracks, but DTS was not part of the original DVD specification (1997), so early DVD players did not recognize DTS audio tracks at all. The DVD specification was revised to allow optional inclusion of DTS audio tracks. The DVD title must carry one or more primary audio tracks in AC-3 or LPCM format (in Europe, MPEG-1 Layer 2 is also an allowed primary track format). The DTS audio track, if present, can be selected by the user. Modern DVD players can now decode DTS natively with no problem, or pass it through to an external decoder. Nearly all standalone receivers and many integrated (“home theater in a box”) DVD player/receivers manufactured today can decode DTS.

A small number of Laserdiscs carry DTS soundtracks. The NTSC Laserdisc format allows for either analog audio only or both analog and digital audio tracks. Laserdiscs encoded with DTS sound replace the LPCM digital audio track with the DTS soundtrack. This soundtrack is output via digital coaxial or optical audio outputs and requires an external decoder to process the bitsream. Consumers without a DTS decoder are only able to listen to the analog audio tracks on the disc.

For PC playback, many software players support the decoding of DTS. The VideoLAN project has created a decoding module for DTS called libdca (formerly libdts), which is the first open source implementation of DTS.^[1]

Sony’s PlayStation 3 and Microsoft’s Xbox 360 are capable of DTS decoding and output via TOSLINK or HDMI as LPCM. However, HDMI output on the Xbox 360 is only found on the “Elite” model and newer models available since mid-2007, with the release of the Falcon chipset.

Codec

In addition to the standard 5.1-channel DTS Surround codec, the company has several other technologies in its product range designed to compete with similar systems from Dolby Labs. Those which conceptually extend DTS (to add more channels and/or more accurate sound reproduction) are implemented as extensions to a core DTS Coherent Acoustics data stream[1]. The core stream is compatible with DTS decoders which don’t support the extension(s); the extension(s) provide the additional data required to implement the additional functionality.

The primary new technologies are:

DTS 70 mm

This is a process designed specifically for playback in motion picture theaters equipped with 70mm projection and 6-track surround sound. The 70 mm DTS prints do not have 6-track magnetic striping, so there is no analog backup should the digital sound fail. The time code track on the film is many times wider than the 35mm version, since it can occupy the real estate formerly taken up by a magnetic track. Theaters with 70 mm DTS frequently install two time code readers for greater reliability.

The gradual disappearance of 70 mm as a common exhibition format has led to DTS-70 being reserved for niche engagements of 70 mm revivals and restorations. Dolby Digital has not been adapted to the 70 mm format.

DTS-ES

DTS-ES (DTS Extended Surround) includes two variants, DTS-ES Matrix and DTS-ES Discrete 6.1, depending on how the sound was originally mastered and stored.^[2] Both variants are implemented in ways which are compatible with DTS decoders which do not include support for DTS-ES.

DTS-ES Matrix provides 5.1 discrete channels, with a matrixed center-surround audio channel. DTS processors that are compatible with the ES codec look for and recognize “flags” built into the audio coding and “unfold” the rear-center sound from data that would otherwise be sent to rear surround speakers. DTS decoders which do not understand ES process the sound as if it were standard 5.1, and the matrixed audio for the center surround channel is output equally from the two surround speakers (very much as a sound intended to be in the centre of the sound field in a stereo recording is played equally by the left and right speakers). This is notated as DTS-ES 5.1.

DTS-ES Discrete provides 6.1 discrete channels, with a discretely recorded (nonmatrixed) center-surround channel; in home theater systems with a 7.1 configuration, the two rear-center speakers play in mono. To maintain compatibility with DTS decoders which do not support DTS-ES, the center-surround channel is also matrixed into the left and right surround channels, so that the rear center channel’s sound is still present when played in 5.1 on a non-ES system; an ES decoder removes the matrixed audio from these two channels when playing back DTS-ES Discrete soundtracks. DTS-ES Discrete is sometimes notated as DTS-ES 6.1. Only a few DVD titles have been released with DTS-ES Discrete.

In contrast, Dolby’s competing EX codec, which also boasts a center rear channel, can only handle matrixed data and does not support a discrete sixth channel; it is most directly comparable to DTS-ES Matrix.

Note: The center-rear/surround channel is encoded and decoded in exactly the same way as the center-front. The center surround channel can be decoded using any surround sound processor by feeding the left and right surround signals to the processor inputs. Left-Center-Right surround is produced. This will work for a “center surround” reproduction, whether the source material is explicitly encoded, as in DTS-ES, or hidden as ambience in any 5.1 source, including DTS-ES 5.1 and Dolby 5.1.

DTS Neo:6

DTS Neo:6, like Dolby’s Pro Logic IIx system, can take stereo content and convert the sound into 5.1 or 6.1 channel format.

DTS 96/24

DTS 96/24 allows the delivery of 5.1 channels of 24-bit, 96 kHz audio and high quality video on the DVD-Video format. Prior to the invention of DTS 96/24, it was only possible to deliver two channels of 24-bit, 96 kHz audio on DVD Video. DTS 96/24 can also be placed in the video zone on DVD-Audio discs, making these discs playable on all DTS-compatible DVD players. DTS 96/24 is implemented as a core DTS stream plus an extension containing the deltas to enable 96/24 sound reproduction.

DTS-HD High Resolution Audio

DTS-HD High Resolution Audio, along with DTS-HD Master Audio, compose the DTS-HD extension to the original DTS audio format. It delivers up to 7.1 channels of sound at a 96 kHz sampling frequency and 24-bit depth resolution. DTS-HD High Resolution Audio is selected as an optional surround sound format for Blu-ray Disc and HD DVD, with constant bit rates up to 6.0 Mbit/s and 3.0 Mbit/s, respectively. It is supposed to be an alternative for DTS-HD Master Audio where disc space may not allow it. DTS-HD High Resolution Audio is implemented as a core DTS stream plus an extension containing the two additional channels plus deltas to enable 96/24 sound reproduction.

DTS-HD Master Audio

DTS-HD Master Audio, previously known as DTS++,^[3] is the second of two DTS-HD audio formats.^[4] It supports a virtually unlimited number of surround sound channels, can downmix to 5.1 and two-channel, and can deliver audio quality at bit rates extending from DTS Digital Surround up to lossless (24-bit, 192 kHz).

DTS-HD Master Audio is selected as an optional surround sound format for Blu-ray and HD DVD, where it has been limited to a maximum of 8 discrete channels. DTS-HD MA supports variable bit rates up to 24.5 Mbit/s on a Blu-ray Disc and up to 18.0 Mbit/s for HD DVD, with two-channel encoded at up to 192 kHz or 8 channels encoded at 96 kHz/24 bit. If more than two channels are used, a “channel remapping” function allows for remixing the soundtrack to compensate for a different channel layout in the playback system compared to the original mix.

All Blu-ray and HD DVD players can decode the DTS “core” resolution soundtrack at 1.5 Mbit/s, however, as DTS-HD Master Audio is also implemented as a standard DTS core plus extensions. DTS-HD Master Audio and Dolby TrueHD are the only technologies that deliver compressed lossless surround sound for these new disc formats, ensuring the highest quality audio performance available in the new standards. (N.B.: DTS Coherent Acoustics’ coding system has been selected as mandatory audio technology for both the Blu-ray Disc [BD] and HD DVD).^[5]

DTS Connect

DTS Connect is a blanket name for a two-part system used on the computer platform only, in order to convert PC audio into the DTS format, transported via a single S/PDIF cable.^[6] The two components of the system are DTS Interactive and DTS Neo:PC. It is found on various CMedia soundcards and onboard audio with Realtek ALC883DTS/ALC889A/ALC888DD-GR and SoundMAX AD1988 chips, as well as several cards based on the X-Fi chipset, such as the SoundBlaster Titanium series and Auzentech‘s X-Fi Forte, X-Fi Prelude, X-Fi Home Theater HD and X-Fi Bravura cards.

DTS Interactive: This is a real-time DTS stream encoder. On the PC, it takes multichannel audio and converts it into a 1.5Mbps DTS stream for output. Because it uses the original DTS codec to transmit audio, fidelity is limited to 5.1 channel at 48kHz, 24bit. More than 5.1 channels, a higher sampling frequency or data rate are not supported, due to the lack of support for DTS variants such as DTS 96/24. It can also be found on some standalone devices (e.g., Surround Encoder). Nearly a dozen titles on the PlayStation 2 feature the “DTS Interactive” real-time stream encoder, such as Grand Theft Auto: Vice City and Terminator 3: Rise of the Machines.

DTS Neo:PC: This is a technology based on the DTS Neo:6 matrix surround technology, which transforms any stereo content (MP3, WMA, CD Audio, or games) into a simulated 7.1-channel surround sound experience. The 7.1-channel surround sound is output as a DTS stream for output via a S/PDIF cable port.

Outros

DTS Surround Sensation: A relatively new development, previously known as DTS Virtual. It allows a virtual 5.1 surround sound to be heard through a standard pair of headphones.^[7]