Ok, not having a television myself I've had no need for HDMI but after showing a friend how to get movies from their laptop to their widescreen TV I noticed that movement can be much jerkier than when I'm watching on my home PC via DVI. After some research I found this was to do with 23.976fps (which I believe is the blu-ray standard) movies not syncing properly somewhere along the line. For some reason turning UAC off sorts this out to an extent, the picture is much smoother (still not quite as smooth as my DVI to monitor) but Audio still goes out of sync after a while. I think it sorts itself out by skipping a frame every 45 mins or something but surely HDMI has been the standard for some time, I would have thought this would have been sorted out by now. The laptop in question has a sandy bridge chip with HD 3000 graphics, I've heard that Nvidia and AMD have similar issues. Would using the on chip audio pass through help at all? At the moment we are using the analogue out from her on-board realtek, as sound from the amp is much better than from her TV. I'm also advising a friend at the other end of the British isles (over the internet) in setting up a home cinema with a laptop (HD3000 again, chosen because it was blue), projector and 5.1 surround sound. The projector I presume won't have any sound capabilities (actually it does have SPDIF in and out) so I was going to suggest a USB soundcard with analogue 5.1 for simplicity with codecs, but is there a way to get the signal to both her speakers and the projector whilst having them both in sync? She hasn't bought a soundcard or speakers yet. Would it be possible to use an HDMI to DVI adapter or would there still be syncing issues?
You've got multiple problems here with your first friend. Those 23.976 fps is what is commonly known as "24p". It's not some blu-ray standard but comes from the cinema and was adopted for the blu-ray format. The Sandy Bridge graphics core (HD2/3000) cannot cope with fractional fps. It was thought that Ivy Bridge would remedy this, but apparently it won't. SB's inability to process true 24p is just part of the problem, though. The real problem is 24p itself. Even though running at 60Hz, as Saspro suggested, introduces some potentially unwanted image processing it just might turn out to be the lesser of two evils. The problem your second friend faces might not be as severe. Since the projector apparently has SPDIF input and output it's not entirely impossible that you could connect the notebook to its input and then connect its output to some dedicated home stereo system. With a bit of luck that might even solve some syncing issues because the projector could delay the output to match the image rendering. For both of your friends it'd be nice to know exactly which equipment (make and model) they're using. I'm referring to both the notebooks and the tv/projector and whatever else they may be using.
Just to add to what azrael- mentions... I have a Radeon HD6770 hooked up to my TV over HDMI (audio over HDMI also), and I had issues with jerky video in some high-def content, particularly very high bitrate content. I haven't noticed problems with the audio going out of sync, but what fixed the jerky playback for me was to allow the PC to change the refresh rate of my TV. I use XBMC as my media centre of choice and there is a setting under the video playback options to match the refresh rate of the display with the video framerate. Every time the TV changes refresh rate (or input) it pops up an info box telling me the current resolution and refresh rate. Previously, the refresh rate for the TV was set to 60Hz - just the standard default settings. Now however, for pretty much all HD content played via the PC, the TV displays at 1920*1080 @ 24Hz (24p) and SD content varies between 50Hz and 60Hz (depending on whether the video is PAL or NTSC). This cleared up any problems I had with jerky framerates; in fact, all video now looks much smoother. The really bizarre part of this equation however is that I know my TV cannot actually display a picture at a 24p refresh rate, and I am well aware of the limitations of 24p. It will accept a 24p input, but it uses 2:3 Telecine Pull-Down to bring the refresh rate up to 60p and displays the video at 60p. I can only assume that the TV can simply handle the refresh rate conversion better than the PC software can. From what I've been reading about 24p, it seems that it may be a blessing in disguise. Although given what azrael- mentions regarding SB's inability to deal with 24p, I'm not sure if it will help you all that much. Plus your TV will need to support the 24p refresh rate in the first place - even if it can't display at that refresh rate, it needs to accept the signal. Either way, it may be worth a shot.
In current status, NOTHING plays 23.976fps at 23.976fps (except NVIDIA doing it right sometimes) http://www.avsforum.com/avs-vb/showthread.php?t=1333324
nVidia isn't doing much better than AMD in this area. However, since you (still) can create custom resolutions with nVidia drivers you just might be able to hit the 23.976 fps dead on. There was an interesting article on Anandtech last June on the performance of discrete nVidia and AMD cards for HTPC purposes. The 24p issue is discussed on page 5, but the entire article is a good read.
