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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  • duploxxx - Tuesday, October 14, 2008 - link

    nice review, gives a clear ups and downs from each part. there's off course always a reason to recommend an intel part in your conclusion even if you brake it to the ground in the earlier pages....this time you took power consumption, which was one part you would already know from the moment you made your base specs. however for a basic htpc people don't buy quadcores, they buy dual's.

    put a 4850e on the plate against e5200 and start all over again, i'am sure you will get a whole other conclusion and 0 reasons to ever buy a s775 platform for htpc in stead you would pick the nvdia/amd offerings with am2 chipset.
  • npp - Tuesday, October 14, 2008 - link

    I suspect the E5200 system would be faster at the end - running at equal clock speeds Core 2 CPUs tend to faster than the old Athlons (at least I think so). I'm not sure what goes for the power consumption, but I really don't understand why one should care about that, anyway. Decent coolers are all around and saving the planet by cutting off some 20-30-50W from your bill is simply ridiculous. As long as we're talking of numbers around the 100W mark, anything goes.
  • strikeback03 - Tuesday, October 14, 2008 - link

    Anandtech has seemed to favor quad-cores for transcoding duties in past HTPC articles.
  • harshaflibbertigibbet - Tuesday, October 14, 2008 - link

    I hope you will also be reviewing the much delayed and finally launched NVIDIA GeForce 9300/9400 chipsets for the Intel platform. In my opinion, they would end up being the best solution for HTPC users.
  • Badkarma - Tuesday, October 14, 2008 - link

    Hi Gary,

    I read through your article which is very good btw. However, I couldn't find what driver versions you were using to test with. Sorry if I just missed it.
  • Golgatha - Tuesday, October 14, 2008 - link

    I have a HTPC running an Intel E8400 C2D, Zalman 9500 HSF, 6GB RAM, a passively cooled ATI 2600 Pro 256MB, Lite-On SATA Blu-ray/HD DVD combo optical drive, Abit IP35-E, 3 hard drives (250GB and 2x750GB), 380w Earthwatts PS, 4 fans (this includes the PS and CPU fan), and a HT Omega Striker 7.1 discreet sound card. The system runs Vista 64bit Home Premium.

    My requirements for a HTPC were for it to be out of sight (tucking it behind the entertainment center and using a Bluetooth Logitech DiNovo Mini works great for me), run cool and quiet, and not use much electricity. Running 2xFolding@Home clients, a Tversity server for my PS3, and playing a Blu-ray movie uses about 115w system power for the entire system (measured with a kill-a-watt brand device).

    I think the configurations tested weren't really representative of how folks build their HTPC, unless you're assuming it's a do-it-all type of PC, which isn't really a HTPC at that point IMO?
    Why in the world would a dedicated HTPC need a quad core CPU or a 520w PSU? Dual core 45nm parts are more than capable of even the most demanding tasks. Also, a 520w PSU for a 100-150w system is completely inefficient.

    http://www.anandtech.com/casecoolingpsus/showdoc.a...">http://www.anandtech.com/casecoolingpsus/showdoc.a...

    Also, barebones motherboards are cheaper than their IGP counterparts by at least $15-$20 (my Abit board was $70 after MIR), which gives a bit of leeway to purchase a $30-$50 dedicated video card that will give a much better end user experience at the end of the day. Also, when something better comes out (hey, I'm interested in AMD's new 4550 etc. series too), you don't have the unnecessary components on the motherboard sucking electricity.
  • fic2 - Tuesday, October 14, 2008 - link

    That is exactly what I don't understand about the recent "HTPC" articles on here. For some reason they think that people actually use quad monster processors for HTPCs. I got a $25 BE-2400 45W cpu that I intend to use in an HTPC, not some 125W beasty thing that triples my power usage.
  • androo - Wednesday, October 15, 2008 - link

    I totally agree! HTPCs are for the living room and should make little to no noise. 140W CPUs have no place in such a rig. Save that for a gaming rig that goes in the bedroom or den (especially if your wife is a light sleeper!).
  • tonyintoronto - Wednesday, October 15, 2008 - link

    I don't get it either. HTPC in my opinion are to be low power systems, dedicated to movies, music and TV... Doesn't make any sense to me to see 3x and quad cores tested. I use a AMD 4450E and i'm already way "oversized", that processor can play all formats of HD running at 1.1GHZ w/out any issues together with a cheap asus 3450 card. That and the gaming performance, who in they right mind would game with integraded graphics? its like showing to 1/4 mile race with a horse and carriage.
    I do agree with them, the 780G and G45 are poor excuses for HTPC boards, IMHO the cheapest possible board with ati 4650 or 4670 makes the most sense. Don't get me started on those 550W power supplies :)
  • Mathos - Wednesday, October 15, 2008 - link

    No idea why they used quad core, other than the fact that a quad would spend more time in low power mode and have lower CPU usage than a dual. That and there are no AMD dual cores out yet that use HT 3.0, although the x2 6500 should be. Most of the AMD based boards are adversely effected by using an older X2 instead of something that uses HT3.0.

    Anyone not seeing the point of a 780g/790gx board, or an nForce 8200/8300 board for an HTPC is not thinking. The point is to not need a discrete card. Many HTPC's use low profile cases, which make finding an adequate video card difficult. Not to mention with the 780g/790gx you can later install a $50 discrete 3650 or 3450 and run it in Xfire with the IGP for better gaming performance. Same goes for the lower end 8000 and 9000 cards on the nforce chipset.

    As far as the PSU goes it leaves room for possibly adding in a discrete card later. Also remember that most PSU's are most effecient at around 50% load which happens on some of the AMD systems under heavy load. Not to mention if you want to have a silent PSU you need to keep the load low so the fan isn't humming constantly, which would happen on a lower rated PSU.

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