The US streaming company has licensed Fraunhofer’s high-quality xHE-AAC software and is using it to encode its entire catalogue of TV series, documentaries and films across a variety of genres and languages.
One of the key features of xHE-AAC for Netflix is the mandatory MPEG-D loudness and dynamic range control metadata, according to Fraunhofer IIS. It allows service providers to embed content- and endpoint-specific metadata in the audio bit stream for transmission which can then be used on the playback side to achieve a consistent loudness level and optimal dynamic range for any playback device and environment.
In a living room environment, a film can be enjoyed with the full dynamic range, the way that the mix was intended, according to Fraunhofer IIS. The same film on a mobile device in a noisy environment might call for loudness management in order to be enjoyed with intelligible dialog. With MPEG-D metadata, a single stream meets the needs of both of these use cases – and everything in between.
Also of interest is xHE-AAC’s improved coding efficiency at low bit rates, its ability to scale up to perceptually-lossless quality at high bit rates, and the built-in seamless bit rate switching. This enables Netflix to always stream with an audio bit rate that matches the currently available internet speed, achieving very high quality for high-bandwidth connections, and minimising rebuffers during network congestion.
“Our xHE-AAC audio codec has been designed from the ground up to improve the consumer experience for entertainment content especially in environments with limited Internet bandwidth,” said Bernhard Grill, director of Fraunhofer IIS. “With Netflix as the leader in video streaming worldwide, we couldn’t have found a better launch partner for xHE-AAC in this market segment.”