In-stream and out-stream video are the most common types of digital video advertising. Each type has its advantages and disadvantages, from the way that these ads are served to how well they engage with an audience.

In-stream Video Ads

In-stream video ads are played before, during, or after a piece of video content. They can be pre-roll (played before the video content), mid-roll (played in the middle of the video content), or post-roll (played after the video content). In-stream is typically skippable after five seconds, but some publishers may allow advertisers to disable the skip button.

Out-stream Video Ads

Out-stream video ads are displayed outside of the main video content. They are typically displayed in native ad units that blend in with the surrounding content. Out-stream can be either autoplay or click-to-play.

In-stream vs Out-stream

Which type of video ads a publisher uses will depend on their website and audience goals. In-stream video ads are usually more engaging and can reach a larger audience, but they can also be disruptive to the user. Out-stream video ads can be displayed on any sort of website and can be targeted more to a specific audience, but they may be smaller and harder to notice compared to in-stream, which can lower viewability rates. Both in-stream and out-stream can be skipped by users. 

There are aspect ratio requirements for both in-stream and out-stream ads, which must maintain standard aspect ratios, cannot interfere with ad content/controls, and cannot obstruct controls. Other requirements include duration limits for in-stream, only one video ad placement playing at any given time, and more. See this list for a full run-down of requirements.

New Criteria from IAB Tech Lab

In August 2022, IAB Tech Lab updated its video ad format guidelines to further differentiate between these two placements. The biggest change is “in-stream video must be sound-on when the player starts,” and in March the IAB added that since it’s possible for browsers (like Chrome) to have auto-mute as a default setting for video players, “explicit demonstrated intent to watch the video” is an additional criteria to broaden the in-stream definition.