SINGAPORE: Despite ongoing debate around effectiveness, desktop pre-roll remains the preferred ad format for advertisers in Southeast Asia even as new investment options are gaining popularity across the region.

According to TubeMogul's Q1 2016 report, desktop pre-roll generates a 90% share of impressions in Thailand and Vietnam, with all Southeast Asian markets seeing upward growth on the previous quarter, Digital Market Asia reported.

However, advertisers are discovering one size doesn't fit all when it comes to ad length – Southeast Asian advertisers are split between investing in 30-second ads versus 15-second ads.

Half of the countries surveyed, including Indonesia, the Philippines, and Thailand, saw more 15-second impressions.

Although mobile is booming across the region, TubeMogul argues Southeast Asian advertisers remain constrained by a lack of data even as inventory increases.

"Despite the introduction of new ad formats, Southeast Asian advertisers are still addicted to the tried and true options available via desktop pre-roll," said Taylor Schreiner, VP of Research at TubeMogul.

"Even though Southeast Asian markets are prolific users of mobile, maturation of this market remains challenged by data limitations despite inventory increasing and CPMs decreasing across the region."

In North Asia, the Japanese market continues to go from strength to strength. Pre-roll inventory in Japan increased 30% in the last 12 months, reaching more than 126m daily auctions in Q1 2016.

Mobile remains one of the fastest growing areas in the Japanese market, with mobile specific inventory up 126% on the previous quarter, contributing to a massive year-on-year increase of 242%.

Advertisers are also seeing significantly higher completion rates on mobile. Mobile completion rates in Japan have grown 24% on the previous quarter and are up 34% overall year-on-year.

Pre-roll ads in Japan have an average completion rate of 60%, with 15-second ads now making up more than half (55%) of total impressions, compared to just 22% a year ago.

Data sourced from Digital Market Asia; additional content by Warc staff