What is a keyframe interval?
A "keyframe interval" refers to the frequency at which keyframes (also known as I-frames) are inserted into a video stream. It determines the rate at which complete, self-contained frames are included as reference points in the video stream.
Keyframes are essential for efficient video compression and playback. They serve as anchor points for decoding and displaying subsequent frames in the video stream. Non-keyframes (such as P-frames and B-frames) rely on keyframes or other reference frames to reconstruct the video content accurately.
The keyframe interval specifies the number of frames between consecutive keyframes. For example, if the keyframe interval is set to 60, a keyframe would be inserted every 60 frames. Smaller keyframe intervals result in more frequent keyframes and potentially larger file sizes, while larger intervals reduce the number of keyframes and result in more efficient compression.
Other names for the keyframe interval in the streaming industry include:
1. GOP Size: GOP stands for Group of Pictures. The keyframe interval is often referred to as the GOP size because it determines the number of frames within each group, with a keyframe acting as the first frame of each group.
2. IDR Interval: IDR (Instantaneous Decoder Refresh) Interval specifies the number of frames between consecutive IDR frames. IDR frames are a specific type of keyframe that allows for resetting the decoder's reference frame buffer.
3. I-Frame Interval: I-Frame Interval refers to the number of frames between consecutive I-frames (another term for keyframes). It indicates how often complete frames are inserted into the video stream.
These terms are used interchangeably to refer to the keyframe interval or the frequency of keyframes in a video stream. They all represent the concept of determining when keyframes are inserted to serve as reference points for decoding and playback.
Keyframes are essential for efficient video compression and playback. They serve as anchor points for decoding and displaying subsequent frames in the video stream. Non-keyframes (such as P-frames and B-frames) rely on keyframes or other reference frames to reconstruct the video content accurately.
The keyframe interval specifies the number of frames between consecutive keyframes. For example, if the keyframe interval is set to 60, a keyframe would be inserted every 60 frames. Smaller keyframe intervals result in more frequent keyframes and potentially larger file sizes, while larger intervals reduce the number of keyframes and result in more efficient compression.
Other names for the keyframe interval in the streaming industry include:
1. GOP Size: GOP stands for Group of Pictures. The keyframe interval is often referred to as the GOP size because it determines the number of frames within each group, with a keyframe acting as the first frame of each group.
2. IDR Interval: IDR (Instantaneous Decoder Refresh) Interval specifies the number of frames between consecutive IDR frames. IDR frames are a specific type of keyframe that allows for resetting the decoder's reference frame buffer.
3. I-Frame Interval: I-Frame Interval refers to the number of frames between consecutive I-frames (another term for keyframes). It indicates how often complete frames are inserted into the video stream.
These terms are used interchangeably to refer to the keyframe interval or the frequency of keyframes in a video stream. They all represent the concept of determining when keyframes are inserted to serve as reference points for decoding and playback.
Article written by
Sylvain Corvaisier
Independent streaming and iOS engineer
Last modified: February 5th, 2025
Sylvain Corvaisier
Independent streaming and iOS engineer
Last modified: February 5th, 2025
