Testing the Slingbox locally and remotely
Because of the placeshifting nature of the Slingbox, I tested using three different environments: on my home network, from a remote location nearby home, and from outside the US.
As you can see from the screenshots, the HD video from my cable box looks great over the local network. The bit rate averaged around 8000 kbps which produced lag-free, HD quality video and high quality audio. Video quality was comparable with what I would expect from an HDTV tuner card.
By default, SlingStream optimization is enabled, which monitors the quality of your Internet connection and gives you the best possible video quality on the fly. With this enabled, I found that it took around five minutes for it to settle and give the best picture.
In the encoding options menu, you can manually adjust each parameter to your liking. Over the local network, I was able to max out everything for best quality without issue.
Controlling the cable box through the Slingbox produced a little bit of lag, but nothing too bad. The only time the actual video lagged was when scrolling through the cable box's programming guide. Other than that, everything was silky smooth.
SD channels looked nice as well, although of course not near as sharp and detailed as their HD counterparts.
I tried using the SlingPlayer's Control Mode, which is said to give priority to the SlingRemote, allowing you to change channels and interface with your video source faster. Enabling Control Mode reduced my bit rate locally from around 8000 kbps to around 2500-3000 kbps and the video quality lagged terribly, almost as if it were in strobe mode. Worse yet, it only seemed to shave off maybe a second at best between changing channels - certainly not worth the trade off.
The next test was accessing the Slingbox over the Internet from a friend's house about 15 miles away. During testing here, the Slingbox bit rate averaged around 1100-1200 kbps. This of course is going to be limited by the upload speed of your home Internet connection. According to Comcast, my upload speeds range "between 384 Kbps and 2 Mbps depending on the service tier". Unfortunately, that isn't very specific. A quick speed test from Speedtest.net resulted in 1300 kbps up.
Regardless, as you can see from the photos above, the picture was very watchable on my laptop running at a resolution of 1280 x 800. Things did become a bit blocky while watching fast moving scenes, but it was still acceptable.
To complete our streaming testing, we traveled all the way to South America (ok, we just had Julio accessing the Slingbox from his location) to see how it performed.
Using a relatively slow Internet connection (1.6 mbps down) we were able to hit a decent 1200 kbps connection to the Slingbox. In terms of picture quality, HD streams still looked better than SD, but the experience depended a lot on the type of content you were trying to watch.
For example, a football game didn't look too pretty when the camera was zoomed out. The experience was about the same with fast motion sequences or otherwise complex scenes. On the other hand, when watching regular scenes from movies or TV shows, cartoons and newscasts, the experience was much improved and certainly decent enough to watch.