Reducing Bitrate and Increasing the Quality of Inter Frame by Avoiding Quantization Errors in Stationary Blocks

Abstract

In image compression and video coding, quantization error helps to reduce the amount of information ofthe high frequency components. However, in temporal prediction the quantization error contributes its valueas noise in the total residual information. Therefore, the residual signal of the inter-picture prediction isgreater than the expected one and always differs zero value even input video contains only homogeneousframes. In this paper, we reveal negative effects of quantization errors in inter prediction and propose a videoencoding scheme which is able to avoid side effects of quantization errors in the stationary parts. We proposeto implement a motion detection algorithm as the first stage of video encoding to separate the video into twoparts: motion and static. The motion information allows us to force residual data of non-changed part to zeroand keep the residual signal of motion regularly. Beside, we design block-based filters which improve motionresults and filter those results fit into block encode size well. Fixed residual data of static information permitsus to pre-calculate its quantized coefficient and create a bypass encoding path for it. Experimental resultswith the JPEG compression (MJPEG-DPCM) showed that the proposed method produces lower bitrate thanthe conventional MJPEG-DPCM at the same quantization parameter and a lower computational complexity.

Keywords

• video compression
• video coding
• motion detection
• mjpeg