Att uverse sound quality.

Http://www.hdtvsupply.com/gefen-ext-homets-home-theater-scaler.html

The link above is how I fixed mine, because I love the way the functions of Uverse works. Here is the problem HDMI and Optical Dolby 5.1 are delivered in digital packets. The DVR at about 48000. These newer HDMI TV and surround sound receivers are processing the sound packets faster than the DVR can deliver it, and hence, when the TV speakers, (HDMI Source) or surround sound receiver optical source, run out of packets or only get 47999 packets from the DVR instead of 48000, there is a momentary drop out. This is either bad chipset in the DVR, or a sync problem with the software. Dish, Direct TV, and almost all of the cable companies have also had this problem. I had dish, and not only would the sound drop out on the HDMI, but I had to turn off the TV and turn it back on to get sound back. It took Dish about 2 years to fix this. Me I am going to ride it out, because I love the way the Uverse features work, and the honesty of the techs that mad my home visits. They told me that they were working on a software push and shooting for August 2010 to fix this. I am going to write ATT Corporate offices by certified mail RRR, and show them what I had to do to fix their false advertisement, and see if they will credit all or some of the cost of this scaler back to me. In the meantime, if you're not using anything but the TV, set your digital audio on the Uverse DVR off of surround back to stereo, and the dropouts will stop, or buy the scaler. It is an excellent workaround, and it also up converts the DVR's 1080 i signal to clean clear and crisp 1080 p, something ATT will never do. It will also convert the component stereo out into dolby digital sound to the HDMI and optical ins on your TV and receiver. THAT IS THE ONLY SOLUTION I HAVE.

I do not have a solution to the audio drop-out/stuttering on the HD channels but I have narrowed it down to DD2.1 (dolby Digital 2.1) feed.
DD2.1 is mainly in use on Spike, TNT, USA, CNN, some NBC,FX, Speed, USA. It does not have issues on DD5.1.
You should check your speaker display(if your receiver has one) since I think most people are thinking the show is producing DD5.1 when in reality, it is spitting out DD2.1 but you are unaware of this format.
This happens on HDMI and Optical interfaces.

This issue only started when I got a new Onkyo Reciever RC360(equivalent to TX-NR609) with HDMI and all the new decoder formats.
My older Harman Kardon which only had optical and component video never had an issue with DD5.1 and DD2.1

It is not just the DVR since I moved my DVR to another TV room and put plain decoder box in my main room. This did not make any difference.

The only thing I can think of, since I was involved in Audio chipset company, is due to all the new decoders and the amount of programmable memory on-chip in these decoders(such as TI, Motorola, etc), these chipset suppliers have stripped pertenant timing code in older formats to provide space for these newer codes. Since I have not gone out and bought other receivers YET to test, I cannot say it is across the board but I will say, stay away from Onkyo.

It has been an issue since Uverse came out. And they haven't fixed it yet. The patch for this fix is 1) hook up RCA analog cables, and put your surround receiver in simulate modes 2) hit pause and then play for a split second on your dvr, and watch the "Live" HD channel slightly in lag 3) get some sort of scaler, that will re-time everything for you. 4) Drop service. ATT has admitted the problem, and has no fix date planned. It is a "known issue", and they just don't get enough complaints to do anything about it. Other than give you a discount on your bill monthly. I have had 4 Uverse accounts in 2 states, at 4 unique locations, using different receivers, and cables. It has never worked, EVER.

It's a known problem. AT&Ts own forum has a 259 page thread on it. Surround sound will drop out. It has nothing to do with the way you're connecting it. If your box is set to surround sound and you are watching a broadcast that is surround sound, your sound will drop out. There is no fix. Some people claim pausing the show and buffering it fixes it but it doesn't. They think it does because they're not watching a broadcast that is in 5.1 surround and then realize later on it "magically started happening again."

AT&T has known about this for over 2 years and they have not done anything about it, even though they advertise their service has 5.1 surround sound. How is that for false advertising?

The repair guys are coming for the 12th time today. I have had fine quality up until now. The DVR is recording it too but it isn't as prominant. The last tech replaced my HDMI cables with component cables (digital vs. analog) and that is not acceptable. Talk about gloves for leaking fountain pens! I think it is IP packet drops and jitter on the outside line. Can't prove it yet though.