What effect does decreasing the GOP size have on I-frames?

Decreasing the GOP (Group of Pictures) size actually increases the frequency of I-frames within a video stream. The GOP structure determines how frames are arranged and encoded in a sequence. In a typical GOP arrangement, I-frames are keyframes that provide a full image and serve as reference points for subsequent frames, which are often predictive (P-frames) or bidirectional (B-frames).

When the GOP size is reduced, it means that I-frames will appear more often throughout the video. This is because a smaller GOP size requires that an I-frame be encoded more frequently in order to maintain the same structure and improve random access to the video stream. More frequent I-frames can also lead to better error resilience and quality in scenes with significant motion or detail changes, as each I-frame can reintroduce the full picture.

Thus, a decrease in GOP size directly correlates with an increase in the frequency of I-frames, making it essential for improving video quality in certain situations.