Netflix has already added 4K and HDR video content to its streaming service, and now the company is adding high-quality audio to the mix as well, which it says delivers "sounds closer to what creators hear in the studio."
The new high quality audio feature captures every detail to offer a richer, more intense experience, says Netflix in an blog post that just went live. For those who have bandwidth of device limitations. The feature is adaptive so you can simply get the best audio experience to match your capabilities, similarly to what's done for video.
Netflix explains in its tech blog that the high quality sound feature, while not lossless, is "perceptually transparent." The audio is indeed compressed, but the company claims that it is indistinguishable from the original source. "Based on internal listening tests, listening test results provided by Dolby, and scientific studies, we determined that for Dolby Digital Plus at and above 640 kbps, the audio coding quality is perceptually transparent," Netflix confirms.
"Sound helps to tell the story subconsciously," says Netflix, "shaping our experience through subtle cues like the sharpness of a phone ring or the way a very dense flock of bird chirps can increase anxiety in a scene. Although variances in sound can be nuanced, the impact on the viewing and listening experience is often measurable."
Netflix decided to pursue enhanced audio when, back in 2017, the team was reviewing Stranger Things 2 with the Duffer brothers in a living room environment. They noticed that, during a car chase scene, the sound wasn't as crisp as it was on the mixing stage. After getting the sound expert involved, Netflix brought together its engineering team, and set on a path to improve the experience. The issue was solved for Stranger Things 2 by delivering a higher bitrate for the audio. But Netflix continued to work on a way to improve audio more broadly for its content and services.
Most TV devices that support 5.1 or Dolby Atmos can receive better sound. Depending on the device and bandwidth capabilities, the bitrate you receive can vary. You get 5.1 from 192kpbs (good) up to 640 kbps (great/perceptually transparent). And with Dolby Atmos, from 448kbps up to 768kpbs. Atmos is only available to members who are subscribed to the premium plan.
Netflix says it expects the bitrates to evolve over time as it gets more efficient with encoding techniques.