OpenMAX
From Wikipedia, the free encyclopedia
OpenMAX is a royalty-free, cross-platform set of C-language programming interfaces that provides abstractions for routines especially useful for audio, video, and still images. OpenMAX is developed by the Khronos Group and intended for devices that process large amounts of multimedia data in predictable ways. OpenMAX provides three layers of interfaces: Application Layer (AL), Integration Layer (IL) and Development Layer (DL).
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[edit] OpenMAX layers
OpenMAX AL is the interface between multimedia applications, such as a media player, and the platform media framework. It allows companies that develop applications to easily migrate their applications to different platforms (customers) that support the OpenMAX AL API.
OpenMAX IL is the interface between media framework such as DirectShow or GStreamer and a set of multimedia components (such as an audio or video codecs). It allows companies that build platforms (for example an MP3 player) to easily change components like MP3 decoders and Equalizer effects and buy components to their platform from different vendors.
OpenMAX DL is the interface between physical hardware, such as DSP chips and CPUs, and software, like video codecs and 3D engines. It allows companies to easy integrate new hardware that supports OpenMAX DL without reoptimizing their low level software.
[edit] OpenMAX AL (Application Layer)
OpenMAX AL accommodates common multimedia application use cases by standardizing a set of representative objects, as well as interfaces on those objects, to control and configure them. The OpenMAX AL API is divided into two profiles: Media Player and Media Player/Recorder. A platform can be compliant to one or both of these profiles by providing all features included in a profile.
It is an application-level, C-language, multimedia API designed for resource-constrained devices. The OpenMAX AL API design puts particular emphasis on ensuring the API is suitable for mobile embedded devices - including basic mobile phones, smart “feature” phones, PDAs and mobile digital music players. Nevertheless, this does not preclude its applicability to other sophisticated media playback and recording devices.
The OpenMAX AL API design devotes particular attention to application-developer friendliness. Its status as an open cross-platform API enables developers to port the same source across multiple devices with minimal effort. Thus OpenMAX AL provides a stable base for application development.
[edit] Features
OpenMAX AL features include:
- Video playback and recording
- Audio playback and recording
- Image capture (camera) and display
- Camera controls
- Radio and RDS
- Basic MIDI playback
- Metadata extraction and insertion
[edit] Specification versions
- OpenMAX AL 1.0 Provisional Specification - a provisional version, dated September 2nd, 2007, to facilitate feedback from the community before the final 1.0 release.
- OpenMAX AL 1.0 Specification is expected to be released during the year 2008.
[edit] Implementations
Currently there are no official OpenMAX AL implementations available since the final 1.0 version of the API hasn't been released yet.
[edit] Comparison with OpenSL ES
OpenSL ES is another Khronos Group API providing a Sound Library for Embedded Systems. OpenSL ES and OpenMAX AL share the same common architecture and have a few common features:
- Audio playback and recording
- Basic MIDI playback
- Metadata extraction
[edit] OpenMAX IL (Integration Layer)
The OpenMAX IL API strives to give media components portability across an array of platforms using the C-language. In the OpenMAX IL, components represent individual blocks of functionality. Components can be sources, sinks, codecs, filters, splitters, mixers, or any other data operator. Depending on the implementation, a component could possibly represent a piece of hardware, a software codec, another processor, or a combination thereof.
The interface abstracts the hardware and software architecture in the system. The OpenMAX IL API allows the user to load, control, connect, and unload the individual components. This flexible core architecture allows the Integration Layer to easily implement almost any media use case and mesh with existing graph-based media frameworks. The key focus of the OpenMAX IL API is portability of media components
The OpenMAX IL API design devotes particular attention to use case flexibility and optimized data transfers between components.
[edit] OpenMAX DL (Development Layer)
The OpenMAX DL API defines a set of low-level multimedia kernels or media processing building blocks. The building blocks might be used to accelerate traditional computational hotspots within standardized media codecs and other integrated media processing engines. The functional scope of the OpenMAX DL interface spans several domains including Signal processing and Image processing, audio coding, image coding, and video coding.
OpenMAX DL is split into five application domains:
- AC - Audio Codecs (MP3 decoder and AAC decoder components)
- IC - Image Codecs (JPEG components)
- IP - Image Processing (Generic image processing functions)
- SP - Signal Processing (Generic audio processing functions)
- VC - Video Codecs (H264 and MP4 components)
OpenMAX DL is, among other companies, openmax_armlibrariesimplemented by ARM and ANSI C sample code can be downloaded from their webpage.
The OpenMAX API is supported by the PlayStation 3 console.
[edit] OpenMAX Working Group
The OpenMAX Working Group was founded alongside sister project OpenVG on July 6th, 2004. Promoting members (2008-01-17) are AMD, Apple, ARM, Creative, Dell Inc, Ericsson, Freescale, Imagination Technologies Group plc, Intel, IBM, Motorola, Nokia, Nvidia Corporation, Samsung Electronics Co. Ltd, SK Telecom, Sony Computer Entertainment Inc, Sun Microsystems Inc and Texas Instruments.
OpenMAX API documentation is publicly available on the Khronos website.
