IntraFrames

IntraFrames, commonly referred to as I-frames or intra frames, are a type of video frame encoded without reference to any other frames in the video sequence. They contain a complete image and serve as a standalone reference point for decoding subsequent frames.

Encoding of intra frames relies on intra prediction, transforming, quantization, and entropy coding applied to blocks within the same frame. The goal is to reduce spatial redundancy inside the frame rather than temporal redundancy between frames. I-frames are typically larger in size than predictive frames because they carry all image information rather than only the differences from other frames.

In a typical video stream, I-frames act as keyframes that enable random access, efficient seeking, and robust error recovery. They also help establish a known reference when scene changes occur. Between I-frames, P-frames and B-frames use temporal references from past and/or future frames to achieve higher compression ratios, making I-frames comparatively heavier in bitrate but essential for reconstructing the sequence accurately.

Across codecs, the exact methods for intra prediction and the number of available prediction modes vary. Modern standards such as H.264/AVC and HEVC/H.265 provide extensive intra prediction options to improve compression of still-like regions within frames. Some codecs also offer intra-only modes or gradual intra refresh techniques to manage bitrate stability during streaming.

In summary, IntraFrames are keyframes encoded without inter-frame references, providing a complete image for decoding, random access, and error resilience, while underpinning the efficiency of predictive frames used in the surrounding sequence.