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Audio Catches Up: Online Video Rocks with Multichannel Audio

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To counter that, Caraeff says that VEVO allocates more bandwidth to the audio in its streams and is also using more efficient codecs, such as Dolby Digital Plus. It is also taking a cue from broadcast and using systems such as Dolby DP600 Program Optimizer to normalize the volume range of its streamed content, which also includes commercials and, increasingly, live events and other original programming. “Some of the commercial content comes from television and listeners experience the same problems in streaming that they do on broadcast television when there are substantial differences in the levels between programs,” he explains. “We’re working to minimize those level differences.”

Audio is subjected to multiple passes of compression as part of a workflow based largely around the Dolby DP600 Program Optimizer, a file-based workflow solution for loudness correction, audio conversion, and upmixing. It includes intelligent audio analysis and an automated loudness normalization engine, along with the ability to encode, decode, convert, or transcode between the following Dolby formats: Dolby Digital, Dolby Digital Plus, Dolby Pulse, and Dolby E bitstreams, as well as PCM, MPEG-1 LII, AAC, HE-AAC, and HE-AAC v2. It also features a newly designed algorithm for upmixing legacy two-channel audio for 5.1-channel delivery. The workflow also reflects the fact that not all of the sources are up to the standards of major labels. Most recent music videos are shot and delivered in 1080p, and the audio is streamed at 192Kbps using the AAC codec. That decreases to as low as 64Kbps for mobile platforms, but Caraeff says that’s still more than many streaming providers are using. (The stream will scale according to the level of connectivity of the device that it’s being received on, but as audio is a fraction of the size of the video stream, sound is less affected as bandwidth decreases.)

Caraeff says that content providers, streaming services, and hardware makers are finally getting on the same page in terms of quality, citing, as an example, HP’s inclusion of Beats Audio technology on its new ENVY line of laptops. Beats Audio is a still somewhat mysterious (based on HP marketing literature) audio processing protocol, developed by record producers Dr. Dre and Jimmy Iovine. It’s also a branded extension of Dre’s Beats line of headphones and earbuds. It’s at least an acknowledgement that consumers care about sound quality. “For the last 20 years, people have been making choices based on convenience, not sonic quality,” Caraeff says, referring to the MP3 format. Now, he says, there is a “renaissance” in consumer attitudes toward the quality of the sound they expect from their entertainment sources.

At the Movies

Movie streaming site VUDU, acquired by Wal-Mart Stores, Inc. in March 2010 and the first on-demand service to offer high-definition movies for download to own, also gets content that ranges from recent HD-quality films to mid-20th-century movies with stereo or even mono soundtracks. All of them are encoded by its third-party processing partner Encompass Digital Media, in Los Angeles, using Dolby Digital Plus, which VUDU CTO and vice president of engineering Prasanna Ganesan says is used for its backward compatibility with Dolby Digital, the most widely used consumer codec. (Ganesan adds that DTS is not used because it lacks that backward compatibility. However, Best Buy and Blockbuster are using DTS for movie streaming riding on Sonic Solutions’ RoxioNow 5.1-channel entertainment platform.) The most common configuration for movie streaming is Dolby Digital Plus streaming audio at 256Kbps, although HD films streamed at 1080p resolution may also have their audio boosted to 384Kbps. VUDU uses a hybrid peer-to- peer TV technology and isn’t streaming at this time to mobile devices, which can’t support the six discrete channels of audio it can transport for surround sound (when the content is supplied with discrete 5.1 audio). Instead, the service differentiates between “living room”— traditional televisions able to link with connected devices such as Apple TV—and “nonliving room” devices, such as laptops and other computers. When the service does begin to encompass mobile devices, Ganesan says, it will use an algorithm on its mobile app to downmix the multichannel audio to stereo.

Mobile will be the ultimate test for audio for video. “We can’t make the screens bigger but we can make the audio appear bigger,” says Eggers. He mentions Nokia’s new N8 phone that has a Dolby Digital Plus decoder installed and has an HDMI connector that would let it output 5.1 and even 7.1 when connected to a multichannel AV receiver. Dolby has also created Dolby Mobile, a portfolio of technologies, such as LFE enhancement and upmixing of stereo to surround that are intended to enhance the movie and other audio on mobile devices. Eggers says the real challenge will be in how well audio for picture adapts to the cloud-based storage and retrieval systems such as UltraViolet, the online locker for movies established by the Digital Entertainment Content Ecosystem, LLC (DECE) alliance that includes Warner Bros. Entertainment, Inc.; Microsoft; NBCUniversal Media, LLC; Sony Corp. of America; and FOX Broadcasting Co. “That’s the next phase for all of this,” he says. 

This article was originally published in the Augest/September issue of Streaming Media magazine under the title "Turn it Up!"

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