It's long perturbed me that I can't watch HD from a cable or satellite receiver on my Mac. Well, actually I (and you) can, though it's a bit of a kludge to make it happen. But, doggone it, I have a 27-inch iMac, and I was determined to find a solution.
If, like me, that's a goal of yours, here's how to to do it. My hardware/software brand of choice for viewing TV on my Mac is EyeTV from Elgato (http://www.elgato.com). Unfortunately, no EyeTV device can receive HD from a cable or satellite receiver. The only device that can do this is the third-party Hauppauge HD PVR (http://www.hauppauge.com/site/products/data_hdpvr.html). The unit comes with Windows software, but can also be used on the Mac (Intel systems only; PowerPC Macs need not apply) with EyeTV 3.1 or later.
The HD PVR captures video in the H.264 video format, using SD and HD resolutions. Audio can be AAC or AC3 (Dolby), depending on the source. That's good. But there are lots of gotchas to using it on the Mac.
The HD PVR doesn't have a tuner input for antenna or cable. The infrared remote receiver isn't supported, and the infrared remote blaster can't legally be supported on the Mac. The minimum firmware supported is 1.15, and the HD PVR must be "flashed" on a Windows machine using Hauppauge’s driver software before you can use it with EyeTV on your Mac.
In other words, you have to hook up the HD PVR to a PC and install the drivers before you can use it with a Mac. If you don't have a PC, you can use Boot Camp, install Windows and do it with your Mac. Or, better yet, get a friend with a PC to "flash" the Hauppauge device for you if, like me, you don't really want Windows on your Mac.
Once you've done all this, you can indeed receive HD from a cable or satellite receiver. As for me, I can now watch my Comcast line-up on my iMac. However, I'm unable to change the channel from the EyeTV channel menu. I can only change it by using the Comcast remote control.
That's normal, and the HD PVR is working normally because the video connections to the HD PVR are only one-way -- outgoing from the cable box. There's literally no way for your Mac to make itself "heard" by the set-top box.
A third party product can simulate the remote signal and allow you to change channels on your cable box directly from the EyeTV 3 software, as described here.
This set-up isn't the smooth solution I'd prefer, but it works (though I hear that Elgato may be working on a solution). My Mac is now my personal computer, stereo, DVD player and sometimes-TV. Now to move onto a Blu-ray workaround...
-- Dennis Sellers