Jae-Ho Hur

Adaptive Local Illumination Change Compensation Method for H.264/AVC-Based Multiview Video Coding

In multiview video, illumination changes can occur due to imperfect camera calibration and variations of the camera position and direction. These characteristics can cause performance degradation in multiview video coding (MVC) that uses inter-view prediction by referring to the pictures obtained from the neighboring views. In order to overcome this problem, an adaptive local illumination change compensation method is proposed. In the proposed method, we compensate for the illumination changes in the macroblock (MB) unit between the current picture and the reference picture under the assumption that the DC component in the MB is influenced by the local illumination changes. By using the proposed method, the compression ratio in the multiview video coding was increased, and a 0.1~0.6 dB peak signal-to-noise ratio (PSNR) improvement was obtained compared with the case where the proposed method was not used.

H.264 to MPEG-4 Transcoding Using Block Type Information

In this paper, we propose a heterogeneous transcoding method of converting an H.264 video bitstream into an MPEG-4 video bitstream. When the H.264 video bitstream is transformed into the MPEG-4 video bitstream, the conversions between the H.264 block types and the MPEG-4 block types are performed by minimizing the distortion, and 4times4 block-based motion vector mapping is performed. The proposed transcoder runs 5.2 times faster than the cascaded transcoding method, while maintaining the similar PSNR (peak-signal-to-noise ratio).

H.264 to MPEG-4 Resolution Reduction Transcoding

In this paper, we propose a heterogeneous transcoding method of converting an H.264 video bitstream into an MPEG-4 video bitstream. The proposed method reduces the spatial resolution for mobile terminals which support only low resolution video bitstreams. When the H.264 video bitstream is transformed into the MPEG-4 video bitstream, the conversions between the H.264 block types and the MPEG-4 block types are performed by minimizing the distortion, and 4 times 4 block-based motion vector mapping is performed. The proposed transcoding method runs on average 5.5 times faster than the cascaded transcoding methods, for a degradation of the PSNR (peak-signal- to-noise ratio) of less than 0.5 dB.

H.264/AVC baseline profile to MPEG‐4 visual simple profile transcoding to reduce the spatial resolution

In this study, we propose a heterogeneous transcoding method of converting an H.264/Advanced video coding (AVC) Baseline profile (BP) video bitstream into an MPEG‐4 Visual simple profile (VSP) video bitstream. The proposed method reduces the spatial resolution for mobile terminals, which support only low resolution video bitstreams. When the H.264/AVC BP video bitstream is transformed into the MPEG‐4 VSP video bitstream, the conversions between the H.264/AVC BP block types and the MPEG‐4 VSP block types are performed by analyzing the macroblocks (MBs) conversion probability and calculating the difference values of motion vector. The proposed transcoding method runs on average 5.5 times faster than the cascaded transcoding methods, for a degradation of the PSNR (peak‐signal‐to ratio) of less than 0.5 dB.