Khronos pumps up the volume with updated mobile audio spec

The Khronos Group is pumping up the volume of mobile devices with an updated 3D audio spec.

As Khronos spokesperson Jonathan Hirshon explains, OpenSL ES 1.1 enables “psychoacoustically” enhanced 3D audio across a wide range of apps, including gaming, videoconferencing, MIDI, music and ringtones.


“OpenSL ES works not only on high-end smartphones and current-gen devices, but also functions on portable designs utilizing older hardware,” Hirshon told TG Daily at a Khronos conference in San Jose.

“Regardless of the platform, OpenSL ES provides a common reference API that allows most devices to achieve the maximum audio performance available to its hardware.”

Hirshon also noted that OpenSL ES 1.1 acts as a fully featured audio API that enables app devs to easily control advanced audio functionality in a device, all while being isolated from platform specifics.

OpenSL ES 1.1 currently supports:

  • Playback – PCM/encoded content, MIDI ringtones and UI sounds.
  • General audio controls – Volume, rate, pitch, equalizer, bass boost, preset reverberation, stereo widening.
  • Advanced 3D effects – Doppler, environmental reverberation and virtualization.
  • Advanced MIDI – SP-MIDI, mobile DLS, mobile XMF, MIDI messages and the ability to exploit MIDI engine output as a 3D sound source.
  • Full 3D positional audio – groups 3D sound sources, audio recording in PCM as well as non-PCM formats.
  • LED and vibrator control.
  • 3D macroscopic control and audio recording. 

A number of industry heavyweights have thus far contributed to the OpenSL ES 1.1 spec, including AMD, Creative, Ericsson, Google, Nokia, Nvidia, Qualcomm and SRS Labs. 

“The Android native audio APIs are based on the Khronos Group’s OpenSL ES.  We [certainly] appreciate [that] Khronos produced a royalty-free, cross-platform audio API for embedded and mobile systems,” a Google rep said.

“Google employees have participated in the maintenance of the current standard and development of a revised standard, alongside representatives of other companies. [We] look forward to continuing this technical collaboration.”