A Fast H.264 Intra Frame Encoder with Serialized Execution of 4 × 4 and 16 × 16 Predictions and Early Termination

  • Authors:

  • Jin-Su Jung;Young-Joon Jo;Hyuk-Jae Lee

  • Affiliations:

  • Inter-university Semiconductor Research Center, Department of Electrical Engineering, Seoul National University, Seoul, South Korea;Inter-university Semiconductor Research Center, Department of Electrical Engineering, Seoul National University, Seoul, South Korea;Inter-university Semiconductor Research Center, Department of Electrical Engineering, Seoul National University, Seoul, South Korea

  • Venue:
  • Journal of Signal Processing Systems
  • Year:
  • 2011

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Abstract

This paper presents a fast H.264 intra frame encoder that processes a single macroblock of 1920驴脳驴1080 size video in 334 cycles on average which is 20% faster than the previous best design. The speed-up is mainly achieved by early termination of either 4驴脳驴4 intra prediction or 16驴脳驴16 intra prediction. The executions of intra 4驴脳驴4 and 16驴脳驴16 predictions are serialized and the second prediction is terminated early by using the cost of the first prediction as the stop criterion. A simple and efficient algorithm by making use of spatial locality is proposed to select the mode that is processed first. To avoid the bubble cycles caused by this serialized execution of 4驴脳驴4 and 16驴脳驴16 predictions, the modified processing order presented in (Jung et al. 2008) is employed for intra 4驴脳驴4 prediction in order to schedule dependent 4驴脳驴4 blocks apart from each other. To further reduce the execution time of 4驴脳驴4 prediction, neighboring pixels with the same value are grouped, and only one prediction mode in the group is evaluated. Experimental results show that the PSNR drop is 0.0619 dB and the bitrate increase is 0.842% when compared with the JM reference software. The additional hardware cost to support the proposed methods is less than eight thousand gates which are very small when compared with the hardware size of a whole intra frame encoder.