Tuesday, July 31, 2012

Video quality of NBC's streaming of the Tour de France (good) and Olympics (bad)

I watched NBC's streaming of the Tour de France (TDF) and am now watching the Olympics. The TDF video quality was good and I watched a ton of it. That contrasts with the Web video of the Olympics, which is un-watchable on my laptop, passable on an iMac and fine on an iPad or iPhone. If you'd like some details, read on. Let's start with the TDF.

During the TDF, download speed was adjusted dynamically. The stream would begin immediately, at 360 Kbps. At that speed, the image was blurry, but, as the video buffer filled, the speed increased and the image cleared up.

The user could display the maximum and current speeds, as shown here.

While the current speed varied automatically (.350, .600, .950, 1.5, 2.1, 3.5 Mbps), the maximum seemed to be fixed during a session -- it was either 2.1 or 3.3 Mbps. Perhaps NBC set the maximum as a function of network load at the time the stream started. Note that the last mile connection at my home was not a constraint. As shown here, I was getting over 16 Mbps at the time.

I watched the Tour on a Dell laptop with 4 GB of RAM, an Intel Core 2 CPU with a 3.06 Ghz clock speed and an Nvidia Quadro FX 770M display chip. The video on my 1,920 x 1,200 pixel display was clear and fluid when the speed was 960 Kbps or more even though, as you see below, I had other application open and the CPU usage was high.

Well, that is the good news, now for NBC's streaming of the Olympics -- the bad news.

Unlike the TDF, video quality was reported in horizontal resolution and the user could control the setting, which ran from 240 to 1040p. There was also an automatic setting, which NBC set at 480p.

I don't know how that automatic level of 480p was chosen, but it was overly optimistic. The video was jerky at that speed, with pauses and jumps. The quality was not good enough to watch a fast moving sport like basketball, and it was disconcerting when watching rowing, a less dynamic sport. At the higher speeds, the video was terrible.

To get fluid video, I had to step down to 360p, but, as you see below, the image is noticeably blurry at full screen. (Click the image to see full full screen size):

I found the video on my laptop unacceptable, so I tried it on my wife's iMac, which has a 2.8 Ghz dual core CPU, 2 GB memory and a Radeon HD2600 display chipset. The automatic quality setting was 480p, as for my laptop, but the video was smoother.

I went back to the laptop, killed all applications, and restarted the video stream. The perceived quality was no better than before. I started the task manager to compare it with the TDF run above. It was using less memory because I had killed other applications, but the CPU performance was more variable. Might that be due to Flash somehow?

I also installed the Olympic streaming apps on my wife's iPhone and iPad. There were no video quality controls, but it turned out that the video ran smoothly and looked good on both.

I suspect that that was due to a combination of fewer pixels to push, optimized hardware and no Flash.

The bottom line is that almost all of my Olympic viewing will be on over the air television, as limited as the coverage is. I won't be watching on the Web, but might watch a little on the iPad or iPhone.