Although there are directors who are not amused – hello, Christopher Nolan – the truth is that the mobile phone has become yet another device to consume series and movies-type content. In fact, in markets like India or Africa, it is almost the only device that many people can use to watch content from VOD platforms such as Netflix, HBO or Disney +. And precisely Netflix wants to improve this experience of mobile use.
The improvement in the sound of the Netflix Android app
The platform started with streaming 5.1 surround sound in 2010, Dolby Atmos in 2017, and adaptive bitrate audio in 2019. Continuing this tradition, Netflix has announced that it will now stream content using the Extended HE-AAC format with MPEG. -D DRC (xHE-AAC) to compatible Android mobile devices. A format that will allow:
Improve intelligibility in noisy environments
Adapt to variable cellular connections
Scale to study quality
The introduction of xHE-AAC with MPEG-D DRC in Android seeks to offer a more consistent sound both when changing program type and within a specific movie, series or documentary. To do this, the update improves loudness management and dynamic range control. Scale the audio to “studio quality”
Some of the Netflix content “- particularly action and suspense -” was amplified to achieve the desired output level. In doing so, the loudest content in these programs is cut off, introducing undesirable harmonic distortion to the sound, so the decoder must apply peak limiting to avoid spurious output.
According to the service, “this is not ideal, but it can be a desirable trade-off to achieve a sufficient level of output on some devices.” Fortunately, the xHE-AAC format offers an option to improve spike protection. The idea is to balance the sound based on what you’re watching, so you don’t have to adjust the volume if you go from watching Bly Manor – where the sound is tuned for a horror experience – to Michael Bay’s 6 Underground – with the sound prepared for shots and explosions-, or to a musical concert.
xHE-AAC uses the metadata to solve some audio problems that people have when watching shows on mobile devices. In a long and technical post, Netflix explains about this technology that it is often a problem of background noise that makes it difficult to hear the contents, combined with weak and tiny phone speakers that sound bad when trying to turn up the volume. . Inconsistent levels of dialogue also mean you have to constantly turn the volume up and down between shows.
xHE-AAC offers better Dynamic Range Control, a technology that reduces the difference between the loudest and quietest parts of a program. Quiet content is louder so that it can be heard over background noise, and the volume of loud content is lowered to avoid clipping, all in theory without sacrificing audio quality. Netflix also maintains that the volume of dialogue remains constant between shows.
The advantage of the xHE-AAC MPEG-D DRC format is that it applies a gentle adjustment when sounds are too loud or too soft for the listening conditions, and also adapts to different listening situations, whether through headphones, from the mobile phone’s speakers or in an environment with background noise.
This is something that you will notice in the contents if you use the Netflix app to watch them. But the technological – qualitative leap brings with it some limitations, since although the Netflix application can be used even with mobile phones with Android 5, to listen to the new sound format you will need your smartphone to have Android 9 installed, so xHE-AAC is compatible with Android 9, Android 10 and Android 11 devices.