Khronos Group Releases OpenSL ES 1.1 Specification
January 25, 2011

Khronos Group Releases OpenSL ES 1.1 Specification

San Jose, Calif – The Khronos Group (Beaverton, OR) today publicly released the OpenSL ES 1.1 specification for high-performance, low-latency audio across any mobile and embedded device platform or operating system. OpenSL ES 1.1 enables psychoacoustically enhanced 3D audio across a wide range of applications, such as gaming, videoconferencing, music and ringtones as well as advanced stereo and MIDI functionality.

OpenSL ES works not only on smartphones and leading-edge mobile devices but also portable designs utilizing older hardware. Regardless of its deployment platform, OpenSL ES provides a common reference API (Application Programming Interface) that enables any device to achieve the maximum audio performance available to its hardware. OpenSL ES is the latest addition to the line of Khronos APIs creating a common platform of hardware-accelerated, cross platform functionality for mobile devices, including OpenGL ES (2D/3D graphics) and OpenMAX IL (system-level multimedia) and OpenMAX AL (application-level multimedia). The OpenSL ES 1.1 specification is immediately available for download at and may be used royalty-free by implementers and developers.

OpenSL ES Details
OpenSL ES 1.1 is a fully featured audio API that enables application developers to control and utilize advanced audio functionality in a device while being isolated from platform specifics. This allows audio-enhanced applications to run on a multitude of hardware-accelerated and software-based platforms. OpenSL ES was designed by many of the leading industry audio experts to provide access to a broad range of audio functionality, including:

  • Playback of PCM and encoded content, MIDI ringtones and UI sounds, as well as extraction of content metadata;
  • General audio controls such as volume, rate and pitch; music player effects such as equalizer, bass boost, preset reverberation and stereo widening, as well as advanced 3D effects such as Doppler, environmental reverberation and virtualization;
  • Advanced MIDI including SP-MIDI, mobile DLS, mobile XMF, MIDI messages and the ability to use the output of the MIDI engine as a 3D sound source;
  • Full 3D positional audio including grouping of 3D sound sources;
  • Audio recording in PCM as well as non-PCM formats;
  • Optional support for LED and vibrator control, 3D macroscopic control and audio recording;
  • Provides a portable foundation for implementing the audio portions of higher-level APIs such as JSR 135 and JSR 234;
Technical details unique to OpenSL ES 1.1 include support for:
  • Buffer queues
  • Content pipes
  • Better application control of 3D performance
  • Explicit object ordering
  • Dynamic sources and sinks
  • Multiple version support
  • Metadata support for streaming playback
  • Extension configuration support
Due to the broad range of audio functionality it offers, OpenSL ES defines three overlapping profiles allowing implementers to select the features required by a particular device while preserving application portability (one or more profiles may be used on a device):

  • The Phone profile provides playback controls and volume controls, sound prioritization and MIDI as well as the ability to direct sound to multiple simultaneous outputs;
  • The Music profile provides balance and pan controls, sound prioritization and audio effects such as virtualization, preset reverberation and equalizer controls;
  • The Game profile provides buffer queues, pitch and playback rate control, environmental reverberation and extensive positional 3D audio controls that complement the use of OpenGL ES for 3D graphics in sophisticated mobile applications.
An Adopters Program for OpenSL ES, including extensive conformance tests to ensure cross-implementation consistency and trademark usage by conformant implementations, will be released by Khronos during the first quarter of 2011. SRS Labs, Inc. also has a complete OpenSL ES v1.1 Phone – Music – Game solution, including all of the optional features and relevant IP blocks required, available for license to interested companies.

OpenSL ES seamlessly integrates with the latest version of OpenMAX AL for a complete multimedia-enhanced mobile solution, with OpenMAX AL providing multimedia playback and recording capabilities while OpenSL ES provides advanced stereo and 3D audio functionality. (EDITORS NOTE: OpenMAX AL 1.1 was announced simultaneously at the Khronos press conference on January 18, 2011 – see press release for further details).

"The enhancements released in OpenSL ES 1.1 and OpenMAX AL 1.1 enable handset manufactures to provide application developers with a truly portable advanced audio and streaming multimedia solution. The combined power of OpenSL ES and OpenMAX AL, linked by their common architecture, has never before been available in a standard developed specifically for mobile solutions," said Neil Trevett, President of the Khronos Group.