HD2000 - The First GPU's Under the AMD Name

THE ULTIMATE HD EXPERIENCE – AVIVO HD

I cannot think that anyone has missed the whole HD-craze that has been going on for the last year or so. While us PC-gamer have been HD-gaming for quite some time now, the rest of the gaming world is finally catching up. We also finally are getting new High Definition video formats that put new demands on the hardware.

AMD has always been in the forefront when it comes to video quality with Avivo and they have of course improved it for the HD2000 series.

Support for HD-playback is really nothing new. Even the X1000 series cards had support for accelerated h.264 playback. The new feature is that AMD has taken the support and improved it in many ways as well as added more support for Blue-ray and HD-DVD playback.

The challenges with HD

As the new HD-content becomes more widespread the demands on the hardware increases. While a regular DVD has a maximum bit-rate of ~9.5 Mbps, the maximum bit-rate for HD-DVD is around ~30 Mbps and for Blue-ray ~40 Mbps. In addition to higher bit-rates both Blueray and HD-DVD introduces new codecs that in turn add even more demands on the hardware.

New codecs use more decode stages and more computational complex stages

CABAC based compression offers very high compression rates 
while minimimizing information loss. The tradeoff is that it is very 
computationally expensive.

Another challenge with HD-content is how it can be played back. Regardless how we feel about it the movie industry has put conditions on how you can watch HD-DVD and Blue-ray on your computer, specifically in Vista.

The Unified Video Decoder

While higher SPEC'd video cards should have no problems playing back video even at the higher bit-rates, there has been a problem to get the lower end cards to manage to play back that material at full HD (1080p). Up until now also the video acceleration of the GPU’s have not accelerated the first entropy decode step in the decode process. This means you had to leave this to the CPU.

AMD has solved these problems with the new Uniified Video Decoder, a little chip that sits on both the HD2400 and the HD2600 (the HD2900XT does not need it as it can handle all this by itself).

The UVD handles the entire decode process, offloading both the CPU and GPU. It supports full 40 Mbps bit-rates optical HD-playback. The decode data is also handled internally which removes any need for passes to the memory (system and GPU) between the decode stages.

In comparison NVIDIA’s G80 only assists on the last two stages of the decode process while their new G84/86 also handles all stages on the GPU (except when the VC1 codec is used, then the first stage still is done by the CPU).

On the G80/G7X, the first two steps are done in the CPU. The G84/86 
however can handle almost everything with the exception of VC1 decoding.
Click on the image for a larger version.

One benefit of UVD is that as the CPU is not used as much, the overall power consumption goes down. For laptop users this will be a welcome feature as AMD claims it means that you will be able to watch a HD-DVD or Blueray movie on one charge.

In addition to the UVD, the HD2400 and HD2600 have custom logic for Avivo Video Post Processing (AVP). This is capable of deinterlacing with edge enhancement, vertical&horizontal scaling and color correction, all on HD-content.

Digital Content Protection

Regardless if you like it or not, the simple fact is that to playback protected video content you need to have hardware that “follow the rules”. On the PC it means that each link in the chain from the optical drive to the screen needs to be “protected” so that no-one can access the video and audio stream at any stage. For the video cards it means that they need to support HDCP, either with HDMI or DVI. Up until now the HDCP-compliant solutions have stored the encryption keys table on an external CryptoRom. The downside with this is that it adds extra cost to the boards and that you cannot be sure all board makers will make their cards HDCP-compliant.

This is how HDCP have been implemented earlier

On the HD2000, AMD has chosen to put the HDPC encryption keys table inside the GPU instead. This means that the board makers no longer need to add an extra chip to the board and thus it both lowers cost as well as ensure that all the HD2000 boards will be fully HDCP-compliant.

HDCP on HD2000

In addition to this, the HD2000 cards will all have as many HDCP ciphers as they have output links. This means that you will be able to run HD content at native resolutions of the dual-links panels (no need to drop the desktop resolution to HD or single-link).

HDMI

The HDMI-connector has basically taken over the TV-market. It is easy to understand why. Instead of having to use different cables for video and audio, HDMI combines everything into one cable. The connector itself also is much smaller and more convenient than a DVI-connector.

The HD2000 of course supports HDMI, albeit ‘only’ v1.2 (NVIDIA supports 1.3). I googled a bit on the difference between v1.2 and v.1.3 and this is what I found:

Increases single-link bandwidth to 340 MHz (10.2 Gbps)
Optionally supports 30-bit, 36-bit, and 48-bit xvYCC with Deep Color or over one billion colors, up from 24-bit sRGB or YCbCr in previous versions.
Incorporates automatic audio syncing (lip sync) capability.
Supports output of Dolby TrueHD and DTS-HD Master Audio streams for external decoding by AV receivers.[9] TrueHD and DTS-HD are lossless audio codec formats used on HD DVDs and Blu-ray Discs. If the disc player can decode these streams into uncompressed audio, then HDMI 1.3 is not necessary, as all versions of HDMI can transport uncompressed audio.
Availability of a new mini connector for devices such as camcorders.[10]
Source: Wikipedia

The “correct” way to support HDMI with both sound and video in Vista is to make sure there is no unsecure path for either. Some current solutions use an extra cable between the video card and the motherboard but that actually is not allowed by Vista. Right now Vista seems to accept it anyway but if Microsoft would to enforce the protected path requirement you can run into issues when trying to get sound over HDMI.

On the HD2000 AMD has built in an audio controller into the GPU. The controller still needs an Audio Codec on the motherboard but there is no need for an extra cable or connection to connect them. All is handled over the North and South bridge making the cards fully compliant with Vista.

The HD Audio system supports the following:

• Microsoft UAA driver (Vista)/ AMD driver (XP)
• 32kHz, 44.1kHz, 48kHz 16-bit PCM stereo
• AC3 (5.1) Compressed multi-channel audio streams such as Dolby Digital & DTS’

Those of you that were paying attention will have realized that on all images of the cards, they still use DVI-connectors. And that is right. Instead of putting an HDMI-connector onto the cards, AMD has opted to include a DVI=>HDMI adapter instead.

This is not your everyday cheap $5 adapter though. Those usually only carry the video portion of the stream and not any audio. The adapter AMD includes takes care of both audio and video.