First Dolby E Encoder And Decoder Models For Digital Broadcast Infrastructure Introduced At NAB ë99

NAB, Las Vegas, April 19, 1999 ñ Dolby Laboratories unveiled the first Dolby E encoder and decoder models at the National Association of Broadcasters (NAB) show this week. Dolby E professional audio coding compression technology is designed to be used by broadcasters and producers to move high bit-rate multichannel audio through their existing digital audio infrastructure prior to encoding into low bit-rate Dolby Digital for delivery to consumers. To help differentiate their functions, Dolby E is referred to as a distribution coding system, and Dolby Digital as an emission coding system.""With the adoption of new digital formats such as HDTV, broadcasters are asking for end-to-end solutions for digital broadcast audio delivery,"" said Tom Daily, Marketing Manager of Broadcast Products at Dolby Laboratories. ""Dolby meets this demand with its Dolby E encoder and decoder models, which allow digital TV broadcasters to smoothly transition their infrastructure to handle multichannel audio without purchasing expensive audio equipment.""According to Dolby, the DP571 Dolby E Encoder and DP572 Dolby E Decoder were designed to ease the transition from two-channel to multichannel audio. This has been a major stumbling block to full multichannel audio delivery of DTV signals, because most of the TV broadcast infrastructure can handle only two-channel digital audio. Dolbyís new technology provides the networks and cable systems a method for getting 5.1-channel digital audio through their two-channel systems. Broadcasters can now distribute six or eight channels of high-quality audio as well as Dolby Digital metadata via a single AES3 pair, or a single AES pair that can be recorded on two audio tracks of a digital video tape, digital audio tape or video server. This occurs where there are two-channel equipment limitations or where bandwidth requirements make multichannel audio costs prohibitive such as satellite capacity. Dolby E enables delivery of multichannel audio to TV affiliate stations, so that they can transmit a multichannel signal to consumers using Dolby Digital. Thus, by wrapping Dolby E encoders and decoders around their existing two-channel digital audio distribution systems, many broadcast facilities can convert to multichannel audio without major modifications or replacement of their audio equipment and routing systems.Dolby E audio will never reach the viewer at home. Like all DTV audio, it is decoded to linear PCM audio and then re-encoded into data reduced Dolby Digital compression coding just prior to transmission. The DP571 encodes at a standard date rate of 1.92 megabits per second based on 20-bit audio at 48kHz resolution at 29.97 frames per second (fps). In the future Dolby E also will support 25 fps, 24 fps, 16-bit and 24-bit audio words. With multichannel programming, a ""5.1+2"" configuration is typically used, with six of the eight channels carrying a 5.1 mix and the other two a Lt/Rt (matrix surround-encoded left total/right total) or stereo two-channel mix. Alternate configurations include a 5.1 mix plus two mono tracks (5.1+1+1), three stereo mixes (3x2), six mono channels (6x1), and so on.Dolby says the technology is designed to accommodate standard broadcast operations and to tolerate without degradation ten of the tandem encode/decode cycles required during the contribution, post-production, and distribution stages of a DTV program. This is the result of a new sophisticated algorithm and low compression ratio. Unlike Dolby Digital, which allows for only one encode (transmission)/decode (reception) cycle, Dolby E, in part because it uses a higher bit rate, allows multichannel programs to be decoded, processed, re-encoded, and edited up to ten times without audible degradation prior to final Dolby Digital encoding and broadcast. In addition, with Dolby E technology audio frame rates match video frame rates (using a standard video ""color black"" reference signal), enabling precise video picture cuts (audio-follow-video edits in the digital domain) without mutes, glitches, restrictions or other aberrations. Dolby Digital, because its frames do not match video frames, is not optimized for editing when changes to the picture are needed. Dolby E enables DTV broadcasters and program producers to switch, route, and perform assemble edits directly on the digital bitstream without decoding and re-coding. Dolby E encoded audio can be recorded on a studio-level digital VTR and switch and edited just like any other digital audio signal. Among its benefits for distribution applications, Dolby E can be used for sending a program to a local TV station for commercial insertion, routing it within the same studio for voice-over editing, or sending it via satellite to another broadcast facility. For Dolby E to work properly, audio for DTV programs need to be maintained in the Dolby E format right up to final master control, and only then re-encoded as a Dolby Digital (AC-3) data stream for transmission.As to the questions: Why Dolby? Why not use Dolby Digital? Dolby says that Dolby Digital is designed for transmission to consumers and is not robust enough for professional manipulation. It has a high bandwidth efficiency (data reduced compression) and is not optimized for multiple encode/decode cycles or editing. Dolby E allows programs to be decided, processed and re-encoded many times without degradation as the signal makes its way through the broadcast distribution chain. Broadcasters can use Dolby E to get the audio to the transmitter, and Dolby Digital to get the audio from the transmitter to consumers.As previously reported, there are complaints about audio/video sync problems with the new ATSC channels (and as well DVD) using Dolby Digital. Dolby says that it licenses the audio decoders to the receiver manufacturers. Part of the licensing agreement calls for Dolby certification before receivers go into production. If Dolby discovers that there is an audio to video synchronization problem due to the receiver design, they say they report the problem to the manufacturer, and request that the product be resubmitted for licensing when the problem is fixed. Dolby says it has the facilities to measure any A/V sync discrepancies in a transport stream sent to them by a TV station. Dolby E also carries Dolby Digital metadata for final delivery to the home viewerís Dolby Digital decoder. Program producers and broadcasters can incorporate within the Dolby Digital bitstream auxiliary information called metadata (i.e. data about the data) to control aspects of the decoding and reproduction of the audio at the viewerís location. In this way all viewers can be serviced, from those with mono TV sets in noisy environments to those with elaborate multichannel home theatre systems capable of a wide dynamic range. Some of these parameters automatically affect playback, while others can be applied, partially applied, or ignored by listeners as appropriate to their equipment and preferences. One metadata parameter can, for example, signify the programís number and type of channels (audio coding modes). Another called ""dynrange"" can be used to compress the audioís dynamic range by a predetermined amount when appropriate (such as late at night), yet allow listeners to opt for full dynamic range when they prefer. ""Dialnorm"" is used to automatically adjust the consumer decoderís output level to produce consistent playback loudness on all programs, including commercials and is referenced to a dialog level parameter.The DP571 Dolby E Encoder and DP572 Dolby E Decoder are being introduced at NAB. The DP571 has a list price of $5,395 and the DP572 has a list price of $3,995. Product shipments are scheduled to begin at the end of summer, 1999. Dolby fully expects their Dolby E technology to become the de facto standard for DTV audio distribution, given the interest by networks, cable and DSS companies.Dolby is offering technical support and implementation assistance on Dolby E products. In addition, there is a two-day multichannel audio training session in San Francisco from June 24-25.For more information phone Tom Daily at 415 558 0200.