What is a Keyframe

In video compression, a keyframe is the full frame of an image; it’s also known as an intra-frame or i-frame. In compressed video, the first frame is a full image. Subsequent frames—called p-frames—contain information about what has changed between each frame. Keyframes are placed at regular intervals throughout a video; these intervals are set in the encoder. In Wowza Streaming Engine™ software, keyframe frequency (keyframe interval / frames per second) is an important consideration. In HTTP, Wowza Streaming Engine™ software breaks chunks on keyframes. Wowza Streaming Engine software can then optimize HTTP streams and corresponding keyframe frequency settings made in the encoder. This article for HLS streaming shows how to make these types of settings. As an example of another type of keyframe setting, the Silverlight player requires a keyframe frequency between 1 and 4 seconds.

NOTE: Keyframe frequency affects seek precision; most players are only able to seek to the nearest keyframe.

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