In the applications of very low bit-rate video coding, the quality of the encoded pictures always suffers from serious degradation due to limited bandwidth. The quantization levels, in typical video coding systems, are adjusted depending only on the fullness of the output buffer while the content of the video is not taken into account. This explains why the picture quality varies saliently in very low bit-rate applications. A content-based bit-rate control scheme is proposed. In this approach, the content of the coded picture is first analyzed to find the main attributes of each macroblock. The attributes of the macroblocks are then consulted while adjusting the quantization levels. In other words, the quantization levels are adjusted not only depending on the fullness of the output buffer but also on the content of the coded material. Simulation results show that the perceptual quality of the coded pictures, by using the proposed method, is better while comparing with the traditional non-content-based approach.
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