Posted by Don Turner – Android Developer Relations Engineer

Header image of audio waves going through phone

This text takes a take a look at what’s modified within the Android ecosystem for audio builders just lately, the audio latency of fashionable Android gadgets, and discusses Android’s suitability for real-time audio apps.

What’s modified?

Over the previous 4 years we now have taken quite a lot of actions which have improved audio latency.

timeline of key events which have had an impact on the audio latency of Android devices. Pre-2017: Google working directly with OEMs to reduce audio latency. Start 2017: AAudio - new high-performance audio API is released. Mid-2018: Oboe - an open source, C++ wrapper for AAudio and OpenSL ES is released. Mid 2019: Pixel 3A is the first 10ms Android phone. Mid 2020: OpenSL ES is deprecated. Start 2021: Oboe has 4bn+ installs

Latency discount

These actions, coupled with a renewed focus from system producers on audio latency, have led to important enhancements within the system ecosystem. The common latency of the most well-liked Android telephones has dropped to underneath 40ms, which is effectively throughout the vary required for real-time purposes.

bar graph showing average audio latency of 20 most popular Android phones. In Jan 2017 it was 109 milliseconds. In Jan 2021 it was 39 milliseconds.

system recognition supply: appbrain.com

Higher consistency

Digging into the info we will see that in 2017 there was a major distinction between the very best and lowest values (222ms).

bar graph showing audio latency of most popular Android phones in Jan 2017. There are 19 in total, all of which are Samsung Galaxy models. The average latency is 109ms, smallest value is 36ms, highest is 258ms, range is 222ms.

system recognition supply: appbrain.com

Evaluate that to the info for 2021. The vary has decreased by an element of eight to only 28ms, offering a much more constant audio expertise. That is extra spectacular when you think about that there are actually a number of OEMs on the most-popular record, in comparison with solely a single producer in 2017. As well as, most of the gadgets on the record should not high-end flagship fashions.

bar graph showing audio latency of most popular Android phones in Jan 2021. There are 20 in total, with models from Samsung, Redmi, Oppo, Huawei and Vivo. The average latency is 39ms, smallest value is 28ms, highest is 56ms, range is 28ms.

system recognition supply: appbrain.com

Faucet-to-tone latency

To this point I have been referring to round-trip audio latency. Spherical-trip latency includes three parts within the audio chain: audio enter, audio processing and audio output.

Many real-time audio apps generate audio from display screen faucet occasions slightly than counting on enter audio. These sorts of apps are delicate to “tap-to-tone” latency – the time taken from tapping on the display screen to listening to a sound. The latency launched by tapping the touch screen is anywhere from 10-35ms, with 20ms being pretty typical on fashionable Android gadgets.

To estimate tap-to-tone latency given round-trip latency, you possibly can subtract the audio enter latency (usually 5ms), and add the contact latency (usually 20ms). In different phrases, add 15ms to the round-trip latency. Given the numbers above, this implies the common tap-to-tone latency of the most well-liked android telephones can also be effectively underneath that required for many real-time audio purposes.

Seeking to the longer term

Regardless of the numerous reductions in audio latency throughout the Android ecosystem our work is nowhere close to full. 20ms round-tip latency is required for Android professional audio apps, and 10ms stays the long run aim. And right now some much less fashionable gadgets nonetheless have excessive audio latency. Nevertheless, if in case you have been holding again on growing an Android app due to audio latency, it could be time to rethink.

To get began, try the Oboe getting started guide or video tutorials.

Knowledge sources and instruments

OboeTester

WALT

appbrain.com

superpowered.com/latency

gsmarena.com

juce.com/maq

numerous inner information sources

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