Audio, Video and Graphics Working Group
Table of Contents:
Audio, video, and graphics processing is at the core of many CE products. The AVG requirements for CE devices are different than those for PCs/Servers, notably with respect to footprint, input devices, interlacing, streaming, etc.. Multiple graphics planes and video planes may be combined using e.g., alpha blending and animation.
No single default/standard interfaces exist for AVG. Having a well defined, well supported interface for AVG devices will reduce fragmentation of solutions and encourage the CE community to develop solutions that apply to conforming interfaces, so that they can be deployed across a wider range of systems.
Emerging Linux API developments have been and will continue to be studied. They may be endorsed if they cover the requirements. Alternatively, they may be extended or new (function level) APIs may need to be defined. The work group may also recommend new drivers for various CE-based AVG technologies not currently included in the kernel distribution.
1. Establish requirements for graphics and video-out presentation APIs from a kernel point of view. The WGs will start here with evaluating existing APIs and recommend solutions. Existing APIs may be endorsed if applicable and the WG may provide implementations for various CE peripherals (firmware).
2. For video-input, a low-level (device/ioctl) API is available (Video for Linux 1/2), but a higher level API may be required. For streaming audio/video, new proposals may be made. Particular attention may be given to audio/video and graphics synchronization issues.
3. For audio, ALSA rather than the default OSS will be considered in the context of CE Linux. If audio proves to be largely independent from video, the Video Graphics charter may also be amended to split off audio. If such a split is necessary, the two WGs would need to maintain a close relation due to AV synchronization requirements.
4. Frameworks for various audio, video, and graphics APIs may need to be discussed and defined.
Ruud Derwig, Philips (mailto:Ruud.Derwig@philips.com)
Relationship to other working groups
* Real Time WG - smooth capture and presentation of audio and video depends on the ability to schedule cyclical tasks with low latency and low jitter, relying on the real-time abilities of the kernel.
* Reliability/File Systems WG - for reliable storage of captured audio/video.
* System Size WG - for CE devices it is essential that the Audio Video Graphics support have a small memory footprint; choices made in one WG will influence the other.
* Focus projects:
2D Graphics (Video out): FB, DirectFB
Audio: OSS, ALSA
AV streaming: Universal Home API
(For more, see Resources below).
Version 2 of the CELF AVG specification AudioVideoGraphicsSpec_V2
Version 1, revision2 of the CELF AVG specification AudioVideoGraphicsSpec_R2
- LinuxDVB: add documentation, extensions to support analog, higher level API, Q1-2
- Philips: Make OS implementation (incl. DVB V4?) of UHAPI PC available
- DirectFB: Acceleration, consider API extensions,…
- AVG/Khronos group: OpenGL ES relation to DirectFB
UHAPI team: detailed look at DVB & DirectFB
Please go to the AudioVideoGraphicsTaskForces page for more details.
Member provided links
Matthew Allum: Fosdem Matchbox presentation
Imre Deak: [[http://linux-omap.bkbits.net:8080/main/src/drivers/video/omap?nav=index.html|src/|src/drivers|src/drivers/video|Omap Bitkeeper: FB driver]]