Hardware Blu-ray Decode Acceleration

Many of the first Blu-ray titles simply had their video encoded in MPEG-2, something that has been accelerated on GPUs for years. What made decoding these MPEG-2 based Blu-ray movies so processor intensive was the sheer amount of data that had to be decoded. While MPEG-2 DVDs ran from 3 - 9Mbps, MPEG-2 Blu-ray discs were in the 20 - 40Mbps range. Pushing more than 10x the bitrate of DVDs made decoding a much more difficult task, regardless of the relative simplicity of the MPEG-2 codec. Things got worse when discs started being authored with H.264 or VC1 for the video stream.

Let's make this very clear: the 1080p video decode quality between all GPUs should be the same. The hardware accelerated side of the decode is simply letting the GPU do the calculations required to reconstruct an individual frame rather than sending them to the CPU, the resulting frame should be the same regardless of what GPU you run it on. It's like how you can guarantee that calculating 2 + 4 on an AMD system will give you the same result as 2 + 4 on an Intel system. That being said, each vendor has its own video optimizations that will try to make the picture look "better", but thankfully most of these optimizations can be disabled.

We used to see differences in video decode quality with interlaced sources because the GPUs would handle the reconstruction of progressive frames differently, but with Blu-ray content stored progressively, de-interlacing is only an issue for watching certain broadcast sources. That being said, while video decode quality should be the same, video offload performance and features will help differentiate these GPUs.

In order to make sure our assumptions were correct we took a few screengrabs from Casino Royale on Blu-ray. Click on the links under the image to compare the outputs from the various chipsets:

AMD 780G

All of the drivers disable any of the features that oversaturate colors or perform any additional postprocessing on the decoded stream, which is preferable especially when your source content is a Blu-ray disc. Because of this, the video output looks nearly identical between all three platforms as expected. Of the three, NVIDIA offers the most control over post processing features in its driver.

24 fps Playback: Perfect on NVIDIA

Most movies are recorded at 24 frames per second, however most displays and graphics cards refresh the screen 60 times per second (60Hz). Enter the home theater space and you'll find a number of displays that can properly output a 24 fps signal, but with an HTPC you'll need a video card that can properly output a 24Hz signal. Support for 24 fps playback isn't necessary, but you'll find that without it wide panning shots won't be smooth as the camera moves from one point to the next. The reason is that it's impossible to evenly divide 24 frames into 60, so some frames end up being displayed more than others (the infamous 3:2 pulldown).

On one end of the spectrum we have Intel's G45 which absolutely does not support proper 24p playback. The G45 still does not have official support for it in the drivers and although 24 fps playback is possible in the hardware, we seriously doubt the software group will implement it (that's a dare).

The AMD 780G/790GX results were very choppy at times; even when they seemed smooth we experienced audio sync problems.

The only platform that can properly handle 24 fps output is NVIDIA's GeForce 8200/8300. It just works.

8-channel LPCM

We've been talking about 8-channel LPCM for quite a while now, if you want to know what this is consult our article on the topic. Currently the Intel G35/G45 and NVIDIA GeForce 8200/8300 chipsets support 8-channel LPCM output via HDMI. AMD continues to trail with 2-channel LPCM output on their chipsets. However, they are offering 8-channel LPCM support on the HD 4xxx series of video cards. Of course that option comes with an additional cost and potential problems such as incompatibility with AVR receivers (i.e. those from Yamaha). NVIDIA removed the option for selecting 5.1 channel support in their HDMI drivers, instead offering only 7.1 for multi-channel setups, but this option returns in a soon to be released audio driver set.

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  • sergev - Monday, January 12, 2009 - link

    A fair comparison? Don't think so! A AMD processor with a 140 Watt TDP and a Intel processor with a 95 Watt TDP?? I wonder why the intel chipsets seem more power efficient? If you are testing the performance, ok seems fair, but power efficiency should be measured with two processors with the same TDP. I am convinced that if you did the same test with a AMD 4850E the AMD would beat the crap out the intel versions on power consumption. But yet again, that would not be fair. So keep in mind that this review is not to be taken al to seriously!
  • axiomhk - Tuesday, October 28, 2008 - link

    Hi, what amazes me is that it seems no reviewers of the AMD IGP chipsets have caught the serious 2D issues referred to here:


    However, the only channel that we consumers / mere mortals have to put pressure on AMD is to send feedback to the Catalyst team. Nothing seems to get done and there is not even any acknowledgement that this issue exists across the HD3200/HD3300 IGPs no matter which manufacturer.

    The 3D performance is hyped up and that's all very well when the chipset has shown that it can deliver, but in fact many users will spend a lot of time on 2D activities which truly suck. This makes a lot of users regret their purchase.

    What the renowned sites such as anandtech and tomshardware can do is try to reproduce the issues, then use their direct contacts to try to see if this issue is being addressed and update the parent article accordingly. Is it possible? Many thanks. GM - Hong Kong.
  • Zap - Wednesday, October 15, 2008 - link

    "The keyboard is not available after drive recognition until the Windows startup routine"

    Try a different keyboard, or a PS/2 keyboard. I had the same problem with two MSI 750a boards and some Razer USB keyboards. No keyboard until Windows. I had to fix a BIOS problem and had to borrow a keyboard - Logitech G15 USB keyboard worked fine.
  • arjunp2085 - Wednesday, October 15, 2008 - link

    Is this not a bit ODD to Compare a $260 to a Lowly Under performing [B}$173 CPU... Geezs This is Grossly inaccurate

    Think about the BOOST to Post Processing and It differs a Whole Lot to the Post processing capability
  • Strid - Wednesday, October 15, 2008 - link

    Yeah, it would have made more sense, IMO, to use lower end processors like AMD 4850E or Intel E5200/7200 which is what most people would use in a HTPC.

    But if you want to do encoding on your HTPC also, I can see the need for a quad core. But not for your average "movie box".
  • Staples - Tuesday, October 14, 2008 - link

    Really, this thing came out like 6 months ago it seems and finally we get some video benchmarks on anandtech. I know it has been commented that it did not work right for months because the video drivers were terrible but I can not believe it really took that long. When I had to get a HTPC, I just bought an Athlon BE and a 780G board. Much cheaper and adequate. Which in hindsight the P45 may have performed better, an Intel CPU and a Core 2 CPU would have driven the price up quite a bit.
  • Kreed - Tuesday, October 14, 2008 - link

    Gary, what are you hinting at with the following statement?

    "That leaves the Intel G45. If you are an Intel fan, this is your only real IGP choice... for the next few days at least."

    Are you suggesting that Intel might be releasing a new IGP over the
  • Kreed - Tuesday, October 14, 2008 - link

    Oops, i didn't get to finish the comment. Here's the comment in full:

    Gary, what are you hinting at with the following statement?

    "That leaves the Intel G45. If you are an Intel fan, this is your only real IGP choice... for the next few days at least."

    Are you suggesting that Intel might be releasing a new IGP over the next few days?
  • Strid - Wednesday, October 15, 2008 - link

    The NVIDIA MCP7A (GeForce 9300/9400 IGP) boards supposedly launches today. They're sockey 775 boards. I'm pretty sure AnandTech will have a review up soon.

  • GPGPUman - Tuesday, October 14, 2008 - link

    AMD 780G and 790GX have 8 stream processors (5-way) for a total of 40 possible ops per clock... NOT 10

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