This paper presents an H.264 intra frame encoder that processes an HD size (1280x720) video at 30 fps with the operating clock frequency of 47 MHz. The low clock frequency is achieved by a novel pipeline schedule that employs the early termination of 16x16 prediction by using the cost of 4x4 prediction as the stop condition. In order to allow the early termination, the proposed pipeline modifies the optimal processing order for 4x4 predictions that avoids bubbles between consecutive 4x4 predictions. For further speed-up, the least probable mode among 9 prediction modes is excluded. With the proposed pipeline schedule, the execution time of 16x16 prediction is saved by 61% for intra prediction of HD size videos. As a result, the required execution time is reduced to 435 cycles which are about 125 cycles faster than the previous best implementation which excludes 2 predictions modes.