In this paper, a scalable multiple description video coding method based on the scalable video extension of H.264/AVC (SVC) is presented. The proposed scheme employs a standard SVC encoder to generate several bit streams which have different bit rates. The spatial enhancement layers of these bit streams are quantized in an unbalanced fashion, while the spatial base layers are coded with the same quantization step size. Balanced multiple scalable descriptions are generated by mixing the pre-encoded scalable bit streams. Each description alone is totally decodable by a standard SVC decoder. A preprocessor before a SVC decoder is employed to extract the packets from the highest quality bit stream. The experimental results show that our proposed scheme achieves improvements of 3.5dB and 3.9dB when compared to the methods based on spatial downspamling and temporal downsampling at 10% packet loss rate.