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Title: Low power architectures for MPEG-4 AVC/H.264 video compression
Author: Bahari, Asral
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2008
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Multimedia communication will be an important application in future wireless communication. The second-generation mobile communication systems already support basic multimedia services such as voice, text-messaging services and still-imaging communication. However, next generation wireless communication technology combined with advances in integrated circuit design and process fabrication technology will allow more data to be processed and transmitted through wireless channels. This will lift the current barriers and enable more demanding multimedia applications such as video telephony, video conferencing and video streaming. Video compression plays an important role in today's wireless communications. It allows raw video data to be compressed before it is sent through a wireless channel. However, video compression is compute-intensive and dissipates a significant amount of power. This is a major limitation in today's portable devices. Existing multimedia devices can only play video applications for a short time before the battery is depleted. This limits the user's entertainment experience and becomes a major bottleneck for the development of more attractive applications. The focus of this thesis is to design a low power video compression system for wireless communication. in this thesis, we propose techniques to minimise the power consumption at the algorithmic and architectural level. The low power is achieved by minimising the switching power between interacting modules that contribute to major the power consumption in H.264 standard. Motion estimation (ME) has been identified as the main bottleneck in MPEG video compression, including in the H.264 system where it takes up to 90% of the coding time. To reduce the power consumption in motion estimation hardware architecture, we have proposed a two-step algorithm that minimises the memory bandwidth and computational load of the ME. In this technique, the search is performed in low resolution mode at the first stage followed by high resolution mode in the second stage. This method reduces the total computation and memory access compared to the conventional method without significantly degrading the picture quality. The simulation results show that the proposed method gives good PSNR as compared to the conventional full search with PSNR drop < 0.5dB. An energy efficient hardware for implementing the proposed two-step method is suggested. The architecture is able to perform both low resolution and high resolution searches without significantly increasing the area overhead. With a unique pixel arrangement, the proposed method is able to perform at both low resolution and high resolution while still being able In to reduce the memory bandwidth. The results show that the proposed architecture is able to save up to 53% energy as compared to the conventional full search architecture.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available