The National Football League’s audience ratings mostly rose after the second week of the season, a sign that the most-popular programming on television may stem two years of shrinking viewership.

After falling 9 percent in Week 1, the audience for NBC’s Sunday Night Football increased 2.9 percent as 21 million people watched the Dallas Cowboys topple the New York Giants 20-13 on their TV sets and online.

CBS, which carried the New England Patriots’ surprise loss to the Jacksonville Jaguars, said its Sunday audience was up 1 percent from last year. At Fox, a rare tie between the Green Bay Packers and Minnesota Vikings drew 17.6 million viewers, up 21 percent from the competing game last year.

The league has been battling headwinds, from bad publicity about head injuries to saturation, with more and more games on the air. John Nallen, chief financial officer at 21st Century Fox Inc., said last week that teams like the Giants, Packers, Chicago Bears and Cowboys didn’t play well last year, which may have hurt. He also said there may be too many games on TV, including matchups in London and Thursday night coverage.

Not every telecast improved. ESPN’s Monday Night Football was down almost 6 percent from a year ago, the second straight decline in the new season, according to early ratings. Thursday’s game on the NFL Network fell 14 percent, according to Sports Media Watch.

“There’s a lot of windows of football,” Nallen said, “and that may have some impact on the ratings.”