An MPEG-4 MAC (Multiple Auxiliary Components) is a good approach when used to encode stereoscopic video with existing standard codec, especially in low bitrate communication applications. We propose a MAC-based stereoscopic video coder and disparity estimation scheme in order to make the proposed coder reliable for lossy disparity map coding. We suggest utilizing a reconstructed disparity map during disparity compensation processes and taking that disparity map into account while estimating base-view sequence motion vectors. We also propose block-based disparity map regularization as well as block splitting in the object boundary and occlusion regions in order to reduce the amount of bits to encode in both the disparity map and residual image. Experimental results indicate that proposed MAC codec outperforms conventional stereo coding by a maximum of 2-3dB in terms of PSNR and 10-18% in terms of bitsaving, notably in low bitrate applications.