While 28 percent fewer people tuned into NBC's Rio Olympics opening ceremony than London's Summer Games four years ago, some of those who did watch Friday night weren't happy with what they considered a series of commercials occasionally interrupted by an opening ceremony.

Viewers took to social media to complain about NBC's heavy ad load during the ceremony, especially early on, and the network's decision to air and stream the ceremony on a one-hour delay.

NBC Sports, however, told Adweek that the ad load was "very similar" to that for the London opening ceremony, but because viewing habits have changed so much in the past four years, the commercial breaks are now more noticeable to audiences.

They sure were. Many viewers took to Reddit and social media (some using the hashtag #nbcfail) to complain about NBC's presentation of the opening ceremony:

In effort to realize record profits from Rio 2016, NBC to become first network to air more than 60 minutes of commercials in a single hour. — Norman Chad (@NormanChad) August 6, 2016

Conversation in NBC conference room. "If we tape delay one hour we can add a full hour of commercials." "Brilliant."#OpeningCeremony — Bob Kevoian (@bobkevoian) August 6, 2016

nbc olympics coverage: where there are commercials about commercials — Sam Stryker (@sbstryker) August 6, 2016

That response could be alarming news for NBC Sports, which has already sold $1.2 billion in national Olympics ads, 75 percent of which accounted for advertising in NBC's prime-time coverage.

"As we did for London, we inserted a few more commercials earlier in the show so that we can afford time later in the show to present as much of the ceremony as we can, including every single country in the Parade of Nations," said an NBC Sports spokesperson. "Given that the commercial load was very similar to London, we believe that consumption habits, such as binge-watching and 'marathoning,' have changed perceptions among the viewing audience regarding commercials."

Once the ceremony got under way, NBC did space out the ad breaks closer to 15 minutes, which was less frequent that the usual seven-minute average between ad breaks.

As for the decision to broadcast and stream the opening ceremony on a one-hour delay, NBC Sports Group chairman Mark Lazarus said last month that while Rio would be the most "live" Olympics yet because it's only an hour ahead of the East Coast, the network was delaying the opening ceremony "to give context to the show. This opening ceremony will be a celebration of Brazilian culture, of the pageantry, of the excitement, of the flare that this beautiful nation has. And we think it's important that we're able to be that in context for the viewer so it's not just a flash of color."

After Friday night's social media outrage, an NBC Sports spokesperson offered a further explanation for the opening ceremony delay: "It's not a sports competition. It's a cultural ceremony that requires deep levels of understanding, with numerous camera angles and our commentary laid over it. We think it's important to give it the proper context. And prime time is still when the most people are available to watch."

The spokesperson added, "Also, presenting it on delay allows us to show the American audience more of the opening ceremony than a live broadcast, which would have portions cut out by commercials."