Dolby truehd (Dolby truehd) Audio Encoding

Source: Internet
Author: User

Dolby truehd is the next-generation lossless compression technology designed for HD disc media. This technology provides excellent audio and HD recording studios with the highest definition, allowing the next generation of CDs to bring you a real HD entertainment experience. With high-definition images, Dolby truehd technology provides an unprecedented home theater experience, allowing you to enjoy the same amazing sound as high-definition images.


    • 100% lossless coding technology.
    • The bit rate is up to 18 Mbps.
    • Supports up to eight separate 24-bit/96 kHz full-band channels. *
    • It is supported by the HD media interface (HDMI). It is a new single-line digital interface that combines audio and video.
    • Supports various metadata functions, including white-to-white and dynamic range control.

* Dolby truehd supports more than eight channels. HD DVDs and blu-ray discs currently have a maximum of eight channels.


    • With the next generation of CD media, you can enjoy a real HD entertainment experience by providing amazing audio quality at the mother band level of the recording studio.
    • More separation and flawless surround sound are provided than before.
    • Compatible with current and future A/V receivers and htibs ).
    • When you switch to another dubi digital and dubi truehd program, you can maintain the same volume level for the white one program.
    • Dynamic Range control (night mode) enables you to play audio as needed, reduce the peak volume (no sudden sound), and understand all the details of audio tracks, so that you can enjoy the strong loop sound in the middle of the night without disturbing others.
    • The mandatory audio standard for HD DVDs and the optional audio standard for Blu-ray discs.

Ensure that your A/V system is compatible with the next-generation HD disc player

Dolby considers your device information

The next generation of HD (HD) disc players will be different from the current sd dvd-Video Player in many aspects. However, whether you have A/V system that uses Dolby Digital Technology in the early days, or A/V receiver with an HDMI interface or external Linear Multi-Channel input, you can rest assured that, we ensure that you have a sound recovery method with good compatibility and high quality. Dolby has taken into account your device situation.

Next-generation CD player

With the development of coding systems, the expansion of optical disc capacity, and the commercialization of blue laser technology, the next generation of optical disc format will bring high-definition image quality. New audio codec, including Dolby Digital + and Dolby truehd, will also bring high-definition sound effects to the entertainment experience.

The next generation of CD format will bring a new level of audio interaction to the playback experience. For example, a fan of a home theater can listen to audio tracks made on a CD while watching high-definition images, this audio track is also mixed with the interpreter stream from the production site in the form of streaming media. As you use the remote control to select different features or programs, you will experience the unique sound effects created by the player.

The most feasible way for the next generation CD player to implement these new interaction features is to process all the relevant audio elements in the player. The video on the DVD adopts the same mode: After decoding the main video, add subtitles or menus, and then output the video as a complete image, which can be a simulation (compound or component) or digital (DVI, HDMI) baseband signal.

In HD (HD) disc players, audio is processed in the same way. Audio streams decoded from the optical disc, audio streams from the Internet or downloaded, or audio elements generated inside the player are decoded as digital PCM signals in the player. PCM is the format used by the player to perform all internal audio processing operations (including sound mixing. In the sound mixing stage, the commentary, button sound, and other non-CD sound in the form of streaming media will be mixed with the original 5.1 or 7.1 audio tracks on the disc, in this way, the sound effects carefully designed by the program producer can be fully realized.


Figure 1:Next-generation six-channel disc player with Dolby Digital Output Decoder


This decoding method in the player is of great significance. Even if the CD has been sold for a long time, you can still create new features for a specific film. More importantly, because audio mixing is performed inside the player, it is not necessary to output the original audio stream from the player like a DVD-video in the future. Therefore, consumers cannot assume that each player can work together with each A/V receiver.

There are now two methods to restore audio streams in the next-generation CD format through A/V receiver or audio processor.

More and more A/V processors and receivers are equipped with IEEE 1394 (FireWire) or HDMI interfaces to transmit up to 8 channels of 24-bit/96 kHz PCM audio programs. If your A/V receiver has this type of next-generation interface, you should seek a next-generation CD media player with similar interfaces. In this connection mode, the PCM signal after mixing is transmitted from the HD player to the/V receiver, which enables easy digital signal processing and bass management.


Figure 2:Connect through the HDMI Interface

Multi-channel simulation interface

The next generation of CD players can also contain linear audio output-a multi-channel hybrid PCM signal transmitted through a digital analog converter. In recent years, the emergence of SACD and DVD-audio has resulted in the addition of 5.1 or even 7.1 external input interfaces to many a/V receivers. If your A/V receiver has an external audio input interface of 5.1 or 7.1, you only need to select a A/V receiver with an external audio input interface of 5.1 or 7.1 to enable full-band playback of audio signals from HD players.

Figure 3:Connect through multi-channel analog input interface


Connecting any of these interfaces allows you to experience the full potential of high definition audio provided by the next-generation CD format.

S/pdif Interface

If your A/V receiver or processor has neither Multi-Channel Simulation nor Digital Input interfaces, but has 5.1-channel Dolby Digital decoding and sound return capabilities, you can still enjoy the 5.1 sound from the next generation of CD players. Included in the 7.1-channel Dolby Digital + and Dolby truehd streams are the core 5.1 audio mixing program prepared by the program manufacturer. This program is used when the player is set to 5.1-channel mode. After the playback signal is mixed in the player, the PCM signal can be encoded into a Dolby Digital Signal and transmitted from the player through S/pdif (optical fiber or coaxial) the interface is output to the Dolby Digital A/V receiver or processor.

In many cases, the sound quality you experience through this connection is superior to that you experience when playing a sd dvd-video album, this is especially true when the original signal on the CD is a dubi truehd or a dubi digital enhancement signal with a high bit rate. This is because a higher quality audio source signal is input to the Dolby digital encoder at a kbps bit rate, which is higher than the highest bit rate of a DVD-video.


Figure 4:Connect through the S/pdif Interface


Because Dolby Digital Coding Technology is not the standard for HD players, you need to find the next generation player with S/pdif output end and built-in Dolby Digital 5.1 audio encoding technology.

Dolby truehd and Dolby Digital + technologies applied in A/V Receivers

The A/V receiver will directly process the Dolby Digital + or Dolby truehd code streams. We are working with IEC and HDMI organizations to update data protocols so that future high-bandwidth interfaces can carry these code streams.

To decode these streams, the/V decoder must support updated data protocols and integrate these new decoding protocols.Algorithm. In addition, you need to select a high-definition CD: The program producer allows the core 5.1 or 7.1 audio streams in the CD to directly transfer the audio stream to the digital output port of the player by bypassing the player's mixing process. We expect specific HD discs to allow this, but they only represent a small part of the video. In essence, the final sound quality will be the same as the audio decoded by the PCM signal in the player, and then transmitted to the/V receiver through the current HDMI interface.

Because the bit rate of six or eight audio channels is 24-bit/96 kHz and the new HD format is used, the digital signal processing (DSP) of the/V receiver is) the requirement is more than doubled. Rather than using a large amount of DSP resources inside the/V receiver to decode core audio signals, it is better to use the DSP resources of the/V receiver for high definition post processing, for example, Bass management, room or speaker balancing, Dolby-oriented logic iix decoding, or other types of digital signal processing.


Figure 5:Connect through the next-generation HDMI Interface

As the new digital interface provides sound quality and many features, hardware manufacturers can provide more highly optimized system designs to achieve the best sound effects, while bringing consumers the maximum flexibility and efficiency.


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