Unified Video Decoder
The Unified Video Decoder (UVD), previously called Universal Video Decoder is the video decoding unit from ATI Technologies to support hardware decode of H.264 and VC-1 video codec standards, and being a part of ATI Avivo HD technology.
OS Support 
- Windows - supported since the launch of the technology. UVD currently only supports DXVA (DirectX Video Acceleration) API specification for the Microsoft Windows and Xbox 360 platforms to allow video decoding to be hardware accelerated, thus the media player software also has to support DXVA to be able to utilize UVD hardware acceleration.
- Linux - since Oct 2008. XvBA (X-Video Bitstream Acceleration) API as designed by AMD for its Radeon GPU is a future extension of the X video extension (Xv) for the X Window System on Linux and UNIX operating-systems that will enable UVD hardware acceleration on those platforms as well.
The UVD is based on an ATI Xilleon video processor, incorporated into the same die of the GPU and part of the ATI Avivo HD for hardware decoding videos, along with the Advanced Video Processor (AVP). UVD, as stated by AMD, handles decoding of H.264/AVC, and VC-1 video codecs entirely in hardware. However, video post-processing is passed to Pixel shaders and OpenCL Kernels. MPEG-2 decoding is not performed within UVD, but in the shader processors. The decoder meets the performance and profile requirements of Blu-ray and HD DVD, decoding H.264 bitstreams up to a bitrate of 40 Mbit/s. It has context-adaptive binary arithmetic coding (CABAC) support for H.264/AVC.
Unlike video acceleration blocks in previous generation GPUs, which demanded considerable host-CPU involvement, UVD offloads the entire video-decoder process for VC-1 and H.264 except for video post-processing, which is offloaded to the shaders. MPEG-2 decode is also supported, but the bitstream/entropy decode is not performed for MPEG-2 video in hardware. Previously, neither ATI Radeon R520 series' ATI Avivo nor NVidia Geforce 7 series' PureVideo assisted front-end bitstream/entropy decompression in VC-1 and H.264 - the host CPU performed this work. UVD handles VLC/CAVLC/CABAC, frequency transform, pixel prediction and inloop deblocking, but passes the post processing to the shaders. Post-processing includes denoising, de-interlacing, and scaling/resizing. AMD has also stated that the UVD component being incorporated into the GPU core only occupies 4.7 mm² in area on 65 nm fabrication process node.
UVD 2 
The UVD saw a refresh with the release of the Radeon HD 4000 series products. The UVD 2 features full bitstream decoding of H.264/MPEG-4 AVC, VC-1, as well as MPEG2 video streams, and in addition it also supports dual video stream decoding and Picture-in-Picture mode. This makes UVD2 full BD-Live compliant.
UVD 2.2 
The UVD 2.2 features a re-designed local memory interface and enhances the compatibility with MPEG2/H.264/VC-1 videos. However, it was marketed under the same alias as "UVD 2 Enhanced" as the "special core-logic, available in RV770 and RV730 series of GPUs, for hardware decoding of MPEG2, H.264 and VC-1 video with dual-stream decoding". The nature of UVD 2.2 being an incremental update to the UVD 2 can be accounted for this move.
UVD 3 
Originally, ATI planned to implement the UVD in its RV550 series GPU aimed at mainstream market, with two different specifications in which one features HDMI and video out support another featuring DVI as well as video-out support, and production was in December 2006, revealed by the slides. However, as of the current date, no information is available about the release of related products. Some suggested the RV550 products were for OEMs, while some speculated the product was cancelled.
Most of the Radeon HD 2000 series video cards implement the UVD for hardware decoding of 1080p high definition contents. However, the Radeon HD 2900 series video cards do not include the UVD (though it is able to provide partial functionality through the use of its shaders), which was incorrectly stated to be present on the product pages and package boxes of the add-in partners' products before the launch of the Radeon HD 2900 XT, either stating the card as featuring ATI Avivo HD or explicitly UVD, which only the former statement of ATI Avivo HD is correct. The exclusion of UVD was also confirmed by AMD officials.
UVD enabled GPUs 
|Codename||Product Name||UVD Version|
|Cayman||Radeоn HD 6900 Series||UVD 3|
|Barts||Radeоn HD 6800 Series||UVD 3|
|Turks||Radeоn HD 6600 Series
Radeоn HD 6500 Series
|Caicos||Radeоn HD 6400 Series||UVD 3|
|Radeоn HD 5900 Series
Radeon HD 5800 Series
|Juniper||Radeоn HD 5700/6700 Series||UVD 2.2|
|Redwood||Radeоn HD 5600/5500 Series||UVD 2.2|
|Cedar||Radeоn HD 5400 Series||UVD 2.2|
|RV790||Radeon HD 4890 Series||UVD 2|
|Radeon HD 4800 X2 Series
Radeon HD 4800 Series
|RV740||Radeon HD 4700 Series||UVD 2.2|
|RV730||Radeon HD 4600 Series||UVD 2.2|
|RV710||Radeon HD 4300/4500 Series||UVD 2.2|
|RV670||Radeon HD 3800 Series||UVD+|
|RV635||Radeon HD 3600 Series||UVD+|
|RV620||Radeon HD 3400 Series||UVD+|
|RV630||Radeon HD 2600 Series||UVD|
|RV610||Radeon HD 2400 Series||UVD|
|RS880||Radeon HD 4200/AMD 785G Chipset||UVD 2|
|Radeon HD 3200/AMD 780G Chipset
Radeon HD 3300 IGP/AMD 790GX Chipset
|M98||Mobility Radeon HD 4800 Series||UVD 2|
|M96||Mobility Radeon HD 4600 Series||UVD 2|
|M92||Mobility Radeon HD 4300/4500 Series||UVD 2.2|
|M88||Mobility Radeon HD 3800 Series||UVD+|
|M86||Mobility Radeon HD 3600 Series||UVD+|
|M82||Mobility Radeon HD 3400 Series||UVD+|
|M76||Mobility Radeon HD 2600 Series||UVD|
|M72||Mobility Radeon HD 2400 Series||UVD|
|M71||Mobility Radeon HD 2300 Series||UVD|
- NB1: Dual-GPU variants with 2 of the latter GPUs.
- NB2: Driver version 8.371 or later must be used if the GPU is "Mobility Radeon HD 2300" for enabling UVD functions for H.264 videos, or system may crash.
See also 
- X-Video Bitstream Acceleration (XvBA) - AMD's future hardware acceleration API for Linux/UNIX operating-system.
- OpenVideo Decode (OVD) – an new open cross-platform video acceleration API from AMD.
- Video Acceleration API (VA API) - an alternative video acceleration API to XvBA for Linux/UNIX operating-system that supports XvBA as a backend.
- ATI Avivo
- DirectX Video Acceleration (DxVA) - Microsoft's hardware acceleration API for Microsoft Windows based operating-system.
- Nvidia PureVideo - the bit-stream technology from NVIDIA used in their graphics chips to accelerate video decoding.
- VDPAU (Video Decode and Presentation API for Unix) from NVIDIA
- Comparison of AMD graphics processing units
- AMD's X-Video Bitstream Acceleration
- (Chinese)HardSpell review
- Smith, Ryan (February 24, 2010). "AMD’s Radeon HD 5450: The Next Step In HTPC Video Cards". AnandTech. AnandTech, Inc. p. 4. Retrieved April 7, 2010. "Since deinterlacing and other AVIVO post-processing actions are done by the shader hardware, the limited shading capabilities of these cards meant that AMD couldn’t offer the full suite of AVIVO abilities at once."
- (Chinese) PC-DVD discussion thread, retrieved August 23, 2008
- http://www.dailytech.com/Radeon+6800+Series+Launches+Targets+GeForce+GTX+460/article19928.htm by Jansen Ng, 10/21/2010 DailyTech
- HKEPC report
- DailyTech report
- http://developer.amd.com/gpu/AMDAPPSDK/assets/OpenVideo_Decode_API.PDF OpenVideo Decode (OVD) API
- ATI Avivo(TM) HD Technology Brief, July 2008
- Presentation slides comparison between CPU decode, ATI Avivo HD and PureVideo HD and Decode comparison of VC-1 and H.264 video
- AMD Media Codecs—optional download