Page 4

PureVideo
Standard and High definition Decoding

Ever since that past generation of graphics cards (Series 6), NVIDIA did something really smart. They made the GPU (the graphics chip) an important factor in en/decoding video streams. With a special software suite called PureVideo you can offload the video encoding/decoding process from the CPU towards the GPU, and the best thing yet it can greatly enhance image quality.

PureVideo HD is is a video engine built into the GPU (this is dedicated core logic) and thus is dedicated GPU-based video processing hardware, software drivers and software-based players that accelerate decoding and enhance image quality of high definition video in the following formats: H.264, VC-1, WMV/WMV-HD, and MPEG-2 HD.

So what are the key advantages of PureVideo? In my opinion two key factors are a big advantage. To offload the CPU by allowing the GPU to take over a huge sum of the workload. HDTV decoding through a TS (Transport Stream) file, for example, can be very demanding for a CPU. These media files can peak to 20 Mbit/sec easily as HDTV streams offer high-resolution playback in 1280x720p or even 1920x1080p without framedrops and image quality loss.

By offloading that big task for the bigger part of the graphics core, you give the CPU way more headroom to do other which makes your PC actually run normal. The combination of these factors offer you stutter-free high quality and high resolution media playback. All standard HDTV resolutions of course are supported, among them the obvious 480p, 720p and 1080i modes and now also 1080P (P=Progressive and I=Interlaced). Ever since the Series 75 ForceWare driver, PureVideo is doing something I've been waiting on for quite some time now, 2-2 pull down which converts 24 frames per second to 50 frame per second PAL. But along with this the new G80 series (and this'll work on G70 as well) will offer HD noise reduction, which is great feature with older converted films. And this is where we land at Image Quality. PureVideo can offer a large amount of options that'll increase the IQ of playback. This can be managed with a wide variety of options. Obviously NVIDIA has some interesting filters available in the PureVideo suite like advanced de-interlacing, which can greatly improve image quality while playing back that DVD, MPEG2 or TS file (just some examples). Aside from that, things like color corrections should not be forgotten. All major media streams are supported by NVIDIA with PureVideo. And yes High Definition H.264 acceleration, which will become a big, new and preferred standard, is also supported.

Paradox: You do not need PureVideo for HDTV playback and connectivity, but it is recommended if you have that dedicated hardware in your system anyway.

Connect your PC to the HDTV screen use the best and thus most expensive connection available. You can go with a component adapter and the 3-way RCA cable. However, and as weird as this might sound, image quality while being good is simply not perfect, it's still analog you know. It's a relatively cheap way to connect to a HDTV screen though. Now what you want to do is to go digital on the connection. Obviously you spent a lot of money on the HDCP (HD Ready) HDTV screen and PC, so invest a little more into digital connectivity. You'll notice that your videocard has a lovely DVI-I/D compatible output, so please use it!

Guru3D uses a DVI-D <-> HDMI cable. Once you boot up into Windows you'll immediately notice the difference; rich colors and good quality. Once booted into windows you'll likely notice some seriously bad overscan (the Pioneer screens are known and feared for this). Basically the outer segments of the screen are not being displayed on your HDTV. NVIDIA is now offering some really cool under and overscan options. In essence you shrink the resolution a little to make it fit perfectly on your HDTV. I believe this is being done by adding black borders to the video signal. The new ForceWare 75 series actually allow independent X and Y underscan control in a very simple manner. Doesn't matter because after you've done that the only thing you can say while playing back an HDTV file is "Oh my God." The image quality is simply beautiful and seems to work extremely well with NVIDIA's recent graphics cards.

To test if the CPU indeed was offloaded by the GPU to see if the PureVideo claims are true we'll put this to the test. Well, obviously it works. With a HD movie (.ts file) we logged CPU utilization during playback.

Support of the .TS files to me personally are important, if your satellite box can record an MPEG stream it'll do that in a .TS file after which you can playback the content through MediaPlayer / MediaCenter easily and without quality loss.

In our case we had a .TS episode recording of the Sopranos (which is our standard test file). This puppy is doing a 12 to 20 mbit/sec datastream which is one of the most difficult things to manage for a PC right now (if you do not have the proper decoders). At standard a mid-range AMD Athlon 64 4000+ would peak out at 55-60% CPU utilization. If we'd use a H.264 file, it'll be 100% easily.

Once you offload it to the graphics processor things look much better with the help of PureVideo. Have a look at the graph below where you are monitoring the CPU at work at roughly 12-20% decoding a HDTV .TS file:

Indeed, a huge improvement over standard decoding. We are now at a CPU utilization of 12-20%, really nice for a HD MPEG2 stream. The processor is almost doing nothing. Let me remind you again that this is a Transport Stream file with a HDTV resolution of 1920x1080i.

In combo with the new drivers you can now also decode High Definition H.264 streams. H.264 is a compression algorithm used to transmit video efficiently between endpoints. This algorithm is seen as the replacement for its predecessor, H.263. What is different about H.264 is that it promises to deliver high quality video, H.264 also enables very high quality encoding, producing way better results than even MPEG2 and of course HDTV levels.

These GeForce series 7 and 8 cards can also manage 3:2 and 2:2 pull down (inverse telecine) of SD and HD interlaced content.

New with the introduction of GeForce 8800 we see a 10-Bit display processing pipeline and also new post-processing options (works for GeForce series 7 as well):

• Adds VC-1 & H.264 HD Spatial-Temporal De-Interlacing
• Adds VC-1 & H.264 HD Inverse Telecine
• Adds HD Noise Reduction
• Adds HD Edge enhancement

With the new PureVideo engine the popular benchmark tool HQV now will score 128 points.

Software like WinDVD, PowerDVD and Nero showtime will support PureVideo from within their software. You can also buy the PureVideo software for a few tenners at NVIDIA after which MediaPlayer or Media Center will work with it flawlessly.

To give you an idea how intensely big one frame of 1920x1080 is with a framerate of 24 frames per second. Click on a the two example images above. Load them up, and realize that your graphics card is displaying that kind of content 24 times per second, while enhancing them in real-time.

It's pretty cool stuff.