PHILADELPHIA (AP) — Comcast Corp. added 43,000 video subscribers in the fourth quarter — the first quarterly gain in six and a half years — as the nation's top cable TV company said that uptake of its X1 set-top box helped it retain customers and boost video-on-demand spending.

Net income in the three months through December rose 26 percent to $1.91 billion, or 72 cents per share, from $1.52 billion, or 56 cents per share a year ago. However, the increase was partly due to a one-time tax windfall of $158 million.

Excluding the tax gain, earnings per share came to 66 cents, slightly below the 68 cents per share expected by analysts polled by FactSet.

Revenue rose 6 percent to $16.93 billion, beating the $16.65 billion expected by analysts.

Philadelphia-based Comcast is rolling out its X1 platform to new customers who sign up for at least three services — Internet, video and voice — and to other top customers where it has supplies. The set-top box allows users to navigate a slick interface like a website which can be controlled through mobile device apps and gives access to more content delivered via the Web. For the upcoming Winter Olympics from Sochi, for example, Comcast is bringing the breadth of NBC's live online coverage to big screen TVs for the first time through the X1 platform.

The company is likely to caution against too much optimism for a turnaround in video, however.

Cable operators have been losing market share to rival telecoms and satellite competitors for years, and fourth-quarter results are generally boosted by college students re-hooking up TVs as they start school and by higher TV use during cold winter months. For the full year, Comcast still lost 305,000 video customers to end the year with 21.7 million.

It added 379,000 Internet customers to finish the year with 20.7 million.

Overall cable revenue rose 5 percent to $10.66 billion in the fourth quarter.

NBCUniversal posted a 7 percent gain in revenue to $6.46 billion, helped by bigger audiences for broadcast network NBC, which has been bolstered by hits "The Voice," ''The Blacklist" and "Sunday Night Football" from the NFL.

The company also said it is boosting its share buyback authorization to $7.5 billion — up from $1.5 billion authorized currently — with $3 billion to be spent in 2014. It raised its quarterly dividend by 15 percent to 22.5 cents per share.