Netflix has detailed an upgrade to its Android app which should reduce buffering and make audio sound better and easier to hear over background noise. It’s been made possible thanks to the adoption of the xHE-AAC codec, which a Netflix blog post says should “improve intelligibility in noisy environments, adapt to variable cellular connections, and scale to studio-quality.” Netflix’s use of the codec was announced earlier this month, and is available on devices running Android 9 and above.
xHE-AAC uses metadata to solve a few different audio problems people have when watching shows on mobile devices. Netflix explains this is often a problem of loud background noise making content hard to hear, combined with weak and tinny phone speakers that sound bad when you try to put up the volume. Inconsistent dialogue levels also mean you have to constantly turn your volume up and down between shows.
Netflix says xHE-AAC offers better Dynamic Range Control, a technology that reduces the difference between the loudest and quietest parts of a show. Quiet content is made louder so you can hear it over background noise, and the volume of loud content is brought down to prevent clipping, all in theory without sacrificing audio quality. Netflix also says that the volume of dialogue is kept consistent between shows.
Before: The volume of dialogue levels (the black bars) are inconsistent, and wide dynamic range means content gets quiet and potentially hard to hear. Image: Netflix After: Dynamic range reduced, so audio can’t get too quiet or too loud, and dialogue volume normalized. Image: Netflix
Finally, the codec also supports “seamless bitrate switching,” which means it should work better in environments with inconsistent internet speeds. Netflix added similar adaptive bitrate functionality to its TV apps back in 2019.
Netflix says that user testing has demonstrated the benefits of the codec. Volume changes between content are “noticeably down” and viewers switch away from using their phone’s built-in speakers 7 percent less often with the new codec. Netflix says it hopes to bring the codec to other platforms that support it. For those keeping track, iPhones have supported xHE-AAC since the release of iOS 13 in 2019.