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.

The Gaming Performance Showdown AMD's Cool'n'Quiet: Disable it
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  • tonyintoronto - Wednesday, October 15, 2008 - link

    The issue is the 780G just doesn't work well enough to be used in htpc.. tons of issues with hdcp and different monitors/tv's, still can't decode mpeg2 stream without crashing the display driver, issues with open GL, was a great idea but bad drivers/hardware have done it for me.. now, the 9300 and 9400 looking nice :)
  • Mathos - Tuesday, October 14, 2008 - link

    Hmmmmm Actually the power numbers aren't too bad when you take it into context. Q9300 is a 45nm chip, and 9950 is 65nm. Q9300 is 95w TDP rated, but runs much lower actual TDP. While the 9950 is rated 125w TDP. I'd be interested in seeing this test redone once Deneb variants come out. Considering the lesser performance of the Phenom compared to the Penryn, it actually speaks well of both the AMD based chipsets, and shows that the 790GX does a lot to make up for the processor.

    I'd say AMD/ATI are doing a good job on the Chipset front now.
  • Calin - Tuesday, October 14, 2008 - link

    Also, considering we're talking about a $174 versus a $260 processor. I wonder what the results were if the comparation would have been against the quad core Q6600 (at a somewhat similar price of $189).
  • 3DoubleD - Tuesday, October 14, 2008 - link

    "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 such as those from Yamaha"

    Can you elaborate on these problems? I was planning on building an HTPC system and was considering this exact combination. Are these temporary (driver update solvable) problems?

    This second question is only distantly related to this article. When using the HDMI with LPCM audio, will sound from sources other than Blu-ray discs (such as games or movies with DD5.1 or DTS) be playable on your stereo? Part of me wants to say yes it will for DTS and DD5.1, but I'm skeptical about video games for some reason. I guess I don't fully understand the extent of the sound card capabilities on these IGP/discrete graphics solutions.

    Great article, I'm looking forward to your HTPC graphics card review.
  • AmdInside - Tuesday, October 14, 2008 - link

    I own the Asus M3N-H/HDMI (Geforce 8300) and except for the fact that it doesn't have an eSATA port, I have no complaints (well, maybe the placement of the 24-pin power connector).

    http://www.asus.com/products.aspx?modelmenu=1&...">http://www.asus.com/products.aspx?model...mp;l1=3&...

    I recently purchased the Intel G45 Mini-ITX motherboard to build a second HTPC and although it has worked ok for the most part, BD and HD-DVD playback just doesn't seem as smooth as the Geforce 8300. It is not choppy. It just feels like the framerate is lower. I can't explain why. The same HDTV was used with both systems and they were both set to 1080p/60. Both systems are running Windows Vista. If you are building a new HTPC, I would not recommend Windows XP btw with these platforms. Anyways, I appreciated the article. For me, I was trying to build a somewhat portable HTPC with the Intel mini-ITX motherboard but given the problems I am having with BD and HD-DVD playback, I think I am going to leave it as a Windows Media Center DVR box and use the Geforce 8300 as my main HTPC. For what it's worth, I tested with both WinDVD and Arcsoft TMT.
  • gipper - Tuesday, October 14, 2008 - link

    It sounds to me like you're really recommending that at this time the way to go is to get a cheap Intel chipset motherboard with the cheapest, lowest power 45nm Core2 Duo, and an ATI 4550.

    But what Intel chipset would give that rock solid platform at the lowest price?
  • tayhimself - Tuesday, October 14, 2008 - link

    Neither AMD nor Nvidia can make a decent chipset. Intel seems to have as many misses as they have hits so they're usually a good bet. Boo hiss to poor QC!
  • Nil Einne - Friday, January 30, 2009 - link

    As with others, I have to say this is a piss poor review. I looked at the Part 1 and came across a resonably decent review. Was expecting the same thing here. But what do I come across? You onmly test two quad cores. What idiot buys a quad core for their HTPC? Unless you're transcoding there's absolutely no reason and given the price of HDs nowadays and the fact that some broadcasters are using AVC for their HD content anyway there's only a few people who are going to bother. Even if you are occasionally transcoding, it's questionable of you really need a quad core or it might be better to just stick with a dual. At the very lest you could have tested quad cores and dual cores like you did with the previous review. But you didn't and so have a fairly useless review for 99% of the population. Why did you even bother with gaming anyway? Seriously, how many people game with quad core IGP systems particularly the kind of games you were testing. And how many of those check out Anandtech reviews? Maybe 5 people in the whole world... You may use a quad core IGP for a high load server or a non-3D workstation but not gaming.

    As it stands, based on your previous review (part 1, i.e. the one with the G35) and your comparison between the G35 and G45 I'm guessing that the 8200 is probably still better when paired with a decent CPU for most HTPC purposes but only barely. Sadly it's just a guess for the reasons I outlined above
  • Nil Einne - Friday, January 30, 2009 - link

    When I said part 1 I meant the "IGP Power Consumption - 780G, GF8200, and G35", got slightly confused. One of the strangest things about this review of course is the 8200 performed so poorly whereas in that review, it was better then the 780G. Has the 780G improved a lot? Is it just the Gigabute 780G was a POS? Who knows, one would have thought the reviewer would have at least co=mmented on if not investigated this but apparently not
  • lisajack - Saturday, January 18, 2020 - link

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