Summary: Alan's first-hand impressions on NVIDIA PureVideo HD with HD-DVD -- comparisons to CoreAVC included.
Christmas came early this year courtesy of FedEx and NVIDIA. I came home Tuesday morning to see an unlabeled brown box outside my door -- no markings other than a FedEx label. What was inside certainly wasn’t plain:
What is PureVideo HD?
From a marketing perspective, “PureVideo HD” is a great idea. The name captures the ultimate goal of the technology, makes for a great logo, and provides easy recognition for the public. It’s a great brand-name. What’s frustrating is that NVIDIA assigns that term to anything and everything that’s video-related. When talking about “PureVideo HD” on the GeForce 6 and 7 platform, we’re really talking about several different things, both hardware and software. (ATI is just as guilty in calling everything AVIVO).
Programmable PureVideo Processor
Every GeForce 6 and 7 with PureVideo (excluding the AGP versions of the 6800 Ultra/GT, and 6100) has a dedicated programmable video processing unit (VPU) on the physical chip. This programmable VPU is separate from the other parts of the GeForce that deal with video (like the scaler) and is also separate from the GPU shader part of the chip. It’s like having a dual-core CPU – one core is the regular GPU, and another core is a completely different VPU or thinking about the Vector Units in the Sony Emotion Engine in the PS2.
The shaders definitely do not come into the picture for H.264 decoding. However, NVIDIA’s de-interlacing and noise-reduction algorithms are accelerated by the shader portion of the GPU to some degree. Although the current algorithms run fine on standard 7600GT, it is possible that NVIDIA will have new algorithms in the future that will benefit from the added shader performance of the 7950GT.
Fixed Function Pipeline
The GeForce 7 GPUs have a 4x5 tap video scaler for both upsampling and downsampling. This means that for each pixel, the GPU is analyzing a total of 20 pixels when scaling the image up. For comparison, the latest AVIVO Radeon’s are 6x10 tap, high-end Faroudja chips are 12x12 tap, and Silicon Optix’s Realta and ReonVX with HQV processing are 32x32-tap. The older GeForce FX and Intel GMA950 were 5x3, and pre-AVIVO ATI Radeon’s were 4x4. In general, the higher-tap filters have had better results however variations in the actual algorithm being used prevent direct comparison.
As you know, there was substantial confusion in the past with determining whether HDCP support was available in the actual board. The PureVideo HD logo mandates board-level support for HDCP, making it easy to figure out. As of October, the NVIDIA boards supporting HDCP are:
The scaler plays a critical role with DVD and HDTV. This is what will transform the 720x480 DVD or 1280x720 or 1920x1080 HD source image into the full resolution of your display (i.e. 1280x1024, 1600x1200, 1920x1200, 2048x1536, 2560x1600). Currently, there is only a limited role for upsampling with HD-DVD / Blu-Ray with today’s hardware. If you have a 1920x1200 display, then no scaling occurs. If you have a smaller sized screen, you’ll actually be downsampling.
One caveat: Dual-link DVI and HDCP
To date, there is only one 2560x1600 monitor with HDCP, the Dell 3007WFP. Unfortunately, there aren’t any graphics cards that are capable of transmitting the HDCP signal to the 3007WFP over the dual-link DVI connection.
* = Reviewed by FiringSquad.com
With the Detonator 90 series, NVIDIA deinterlacing features were activated for any DXVA application. However, NVIDIA continues to develop and support their PureVideo MPEG-2 Decoder. The PureVideo decoder is considered to be one of the best MPEG-2 decoders on the market and is the preferred decoder in Windows Media Center Edition 2005, even with ATI users.
HD-DVD and Blu-Ray Drives
A Fast CPU
You won’t need a fancy CPU for VC-1 or MPEG-2 based HD-DVD/Blu-Ray movies, but for MPEG4 AVC (H.264), you’ll need a flagship CPU even with hardware-accelerated video processing. A Core 2 Duo Extreme E6700 running at 2.66GHz will barely be able to decode the most compute-intensive H.264 video. With PureVideo HD, a standard Core 2 Duo E6300 or Athlon64 X2 running at 2.2GHz or faster will work. You may be able to get by with lower bitrate H.264 video if you have a Pentium D930 or Athlon64 X2 2.0 GHz, but we wouldn’t recommend it.
Before we get to the tests…
It’s worth spending 2 minutes to talk about the benefits of HD video. I’ve seen several articles in the mainstream press that claim that there’s no “significant difference” in quality between upsampled DVDs and HD-DVD/Blu-Ray content. The mainstream press will also claim that they can’t tell the difference between 30 fps and 60 fps…
Note: In the following images the 1080i image is on the left, DVD right
With HDTV, you can actually appreciate the fabric that’s made from self-regulating unstable molecules.
You can watch Star Wars on broadcast HDTV… but you can’t actually buy a HD-DVD or Blu-Ray of it yet… Look at Padme’s eyes.
There’s a small difference in the clarity of the eyeglasses – it’s not a huge difference.
While the DVD quality isn’t bad, the screenshot from broadcast HDTV is clearly sharper.
Isn’t it amazing how the Audi R8 actually looks better than the car in I, Robot? Look at her leather jacket for the difference between HDTV broadcast and regular DVD.
Even older movies will benefit. I expect the Blu-Ray version of Gattaca to be even sharper.
Even older movies can benefit from HD remastering.
Most HD content is still coming from broadcast HDTV. Spend $50 on a HDTV tuner card, get a GPU with content-based 1080i inverse telecine, and you’ll be golden.
Remember, these clips are all from broadcast MPEG-2 HDTV. HD-DVD and Blu-Ray discs will often look better than broadcast HDTV due to higher bitrates and more advanced codecs such as H.264 or VC-1!
Our PureVideo HD test system came from NVIDIA as a preconfigured machine:
Silverstone SG01-Evolution MicroATX Case
Intel Core 2 Duo E6400
ASUS P5LD2-VM i945 motheboard
1GB PC-5200 DDR2-RAM
MSI NX7600GT Diamond Plus DVI/HDMI
Toshiba TS-L802A Slim HD-DVD drive
Antec Neo420W Power Supply
Windows XP Professional SP2
PowerDVD 6.5 HD-DVD Edition (Sept 22, 2006 Build; H.264 Decoder Version 184.108.40.2060)
We compared CyberLink’s software decoding with CoreAVC 1.1 Pro.
NVIDIA provided the following HD-DVDs to test:
The last two discs are imported from Japan. Virtual Trip - Yozakura is part of Pony Canyon’s “Virtual Trip” series of HD-DVDs which showcase Japanese cities. Pony Canyon is famous among audiophile circles as producing some excellent music CDs and this disc shows that they have brought that same attention to detail to these HD-DVDs. True Blue is produced by Columbia Music (founder of DENON; not Columbia Pictures) and Toshiba. This is also a demo disc that has video footage of undersea creatures. Although the average bitrate is small, the complexity of the underwater scenes represent a substantial challenge to the H.264 decoder.
We added our own test clips to the mix:
These test clips are standard transport streams with AC-3 audio, meaning they will be less computationally intensive in comparison to the HD-DVDs (which must do AACS decoding, audio mixing, and deal with more complex H.264 encoding).
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