Video Acceleration API

From Wikipedia, the free encyclopedia
Jump to: navigation, search
libVA
Original author(s) Intel
Initial release September 13, 2007; 9 years ago (2007-09-13)
Stable release
1.7.3 / November 10, 2016; 23 days ago (2016-11-10)
Written in C
Operating system Linux, Android, and BSD-based systems
Type API
Library
License MIT License
Website www.freedesktop.org/wiki/Software/vaapi

Video Acceleration API (VA API) is a royalty-free API as well as its implementation as free and open-source library (libVA) distributed under the MIT License.

The VA API interface is to be implemented by device drivers to offer end-user software, such as VLC media player or GStreamer, access to available video acceleration hardware, such as PureVideo (through the libva-vdpau driver, which implements VA API in terms of VDPAU) or Unified Video Decoder.

The API enables and provides access to hardware-accelerated video processing, using hardware such as graphics processing units (GPU) to accelerate video encoding and decoding by offloading processing from the central processing unit (CPU).

VA API video decode/encode interface is platform and window system independent but is today primarily targeted at Direct Rendering Infrastructure (DRI) in X Window System on Unix-like operating systems (including Linux, FreeBSD, Solaris), and Android, however it can potentially also be used with direct framebuffer and graphics sub-systems for video output. Accelerated processing includes support for video decoding, video encoding, subpicture blending, and rendering.[1]

The VA API specification was originally designed by Intel for its GMA (Graphics Media Accelerator) series of GPU hardware with the specific purpose of eventually replacing the XvMC standard as the default Unix multi-platform equivalent of Microsoft Windows DirectX Video Acceleration (DxVA) API, but today the API is no longer limited to Intel-specific hardware or GPUs.[2] Other hardware and manufacturers can freely use this open standard API for hardware accelerated video processing with their own hardware without paying a royalty fee.[3]

Overview[edit]

The main motivation for VA API is to enable hardware-accelerated video decode at various entry-points (VLD, IDCT, motion compensation, deblocking[4]) for the prevailing coding standards today (MPEG-2, MPEG-4 ASP/H.263, MPEG-4 AVC/H.264, and VC-1/WMV3). Extending XvMC was considered, but due to its original design for MPEG-2 MotionComp only, it made more sense to design an interface from scratch that can fully expose the video decode capabilities in today's GPUs.[5]

Supported hardware and drivers[edit]

As of January 17, 2012 VA API is natively supported by :

Supported video codecs[edit]

VA API currently supports these video codecs in the official mainline version, but note that exactly which video codecs are supported depends on the hardware and the driver's capabilities.

  • Supports MPEG-2 decode acceleration Main Profile
  • Supports VC-1 / WMV3 decode acceleration Advanced Profile
  • Supports MPEG-4 Part 2 (H.263) (a.k.a. MPEG-4 SP / MPEG-4 ASP, more commonly known as Xvid) decode acceleration
  • Supports H.264 AVC encode acceleration Main Profile
  • Supports H.264 AVC decode acceleration High Profile
    • H.264 / AVC Hardware Variable Length Decoding (VLD) - CABAC
    • H.264 / AVC Hardware Variable Length Decoding (VLD) - CAVLC
    • H.264 / AVC Hardware Inverse Transform (IT)
    • H.264 / AVC Hardware Motion Compensation (HWMC)
    • H.264 / AVC Hardware In-Loop Deblocking (ILDB)

Processes that can be accelerated with VA API[edit]

Video decoding and post-processing processes that can be offloaded and accelerated if both the device drivers and GPU hardware supports them:

Software architecture[edit]

Video Acceleration API (VA API) interface architecture

The current interface is window system independent, so that it can potentially be used with graphics sub-systems other than the DRI (Direct Rendering Infrastructure) in X Window System, such as direct with framebuffer, and it can work with third-party DRM (Direct Rendering Manager) libraries. In a nutshell, it is a scheme to pass various types of data buffers from the application to the GPU for decoding or encoding a compressed bit-stream.

Sources[edit]

"The main motivation for VA-API (Video Acceleration API) is to enable hardware accelerated video decode/encode at various entry-points (VLD, IDCT, Motion Compensation etc.) for the prevailing coding standards today (MPEG-2, MPEG-4 ASP/H.263, MPEG-4 AVC/H.264, and VC-1/VMW3)." http://www.freedesktop.org/wiki/Software/vaapi

"A new video acceleration API is being developed, in an effort led by Intel. This new API supports more complete offload (VLD) as well as iDCT+MC, and can support acceleration of MPEG4, H.264, VC-1, as well as MPEG-2." http://www.mythtv.org/wiki/XvMC

The "VA API" and "libVA" can also be read about here: "The end user impact is improved performance of H.264, VC-1, MPEG-2 and MPEG-4 video playback with media players that use the new API compared to playback using a pure software implementation." https://wiki.ubuntu.com/mobile-hw-decode

Software supporting VA API[edit]

Some software may gain VA API support in the future : Lightspark (Flash / SWF player),[22] and Xine (via "xine-lib-vaapi" library).[23]


See also[edit]

References[edit]

External links[edit]