Dolby Digital Plus
Dolby Digital for High Definition broadcasts
Dolby Digital Plus, along with Dolby Digital TrueHD, is one of the next generation audio formats from Dolby labs, which is intended for high definition broadcast TV. It’s a discrete 7.1 channel system of surround sound. The audio compression algorithm is designed to present broadcasters with the efficiency and flexibility of Dolby’s audio encoding without abandoning the full impact of the surround soundtrack. The new system is also designed to bring the new enhanced multi-channel surround tracks to the compressed world of broadcast HD. Look for Dolby Digital Plus anywhere you see HD content being sent over a line with limited bandwidth.
This new format isn’t to be confused with the other new Dolby Surround format: Dolby “Digital True HD”. While True HD is also an extended format, on the other hand, it is designed with bandwidth efficiency in mind. Dolby Digital Plus is designed to be used when media is broadcast over a limited pipeline. As such, it’s probably very similar to the original Dolby Digital design, which does a very good job of encoding multi-channel surround tracks into the limited space of a DVD.
Dolby has lost some ground to DTS. Many people who have compared these systems believe that DTS is a superior system for pure audio quality. However, there are many individuals who argue that there is no difference at all between Dolby and DTS. Although the audio quality of Dolby may be marginally inferior to DTS, an advantage of Dolby Digital is that it is able to compress more of its soundtrack into a smaller size.
Dolby Digital plus Highlights
- Capable of multi-channel audio in multiple programs at 7.1 each through a single bit stream.
- Backward compatible to Dolby Digital 5.1
- Supported by HDMI
- Mandatory surround track for HD DVD and optional for Blu-Ray discs.
- Selected by the ATSC as the future standard for DVB (Digital Video Broadcast)
Dolby Digital Plus can deliver up to 6Mbps, enough for multiple program channels at 7.1 channels of audio each. This means you could have several soundtracks to choose from. This might be used for broadcasters sending multi-language tracks with each language getting equal multi-channel sound quality. Dolby Digital Plus will deliver these program channels from a single encoded bit stream to a receiver that can decode the material. So far 7 and 8 channel receivers are rare, but this is the future of audio. Media is going to be hitting these future generation receivers from a variety of sources, not just optical storage discs like DVD. Dolby has created Plus to be a flexible medium to meet future digital audio demands. Audio encoded in Dolby Digital Plus will be just as effective when transported across HDMI 1.3 as it is from a digital connection to a PC. If your receiver can only decode Dolby Digital 5.1, as most on the market today, don’t worry. You’ll get the full benefit of a soundtrack that is encoded natively into 5.1 without losing any sound quality or any of the separation effects you’re looking for.
