In this thesis, we design an SVC encoder with two spatial scalability layers for real-time applications. JSVM, the current reference software of SVC standard, is very slow and cannot meet the requirements of real-time encoding. To achieve the goal of real-time encoding, the proposed encoder adapts many methods and algorithms such as multi-threading, SIMD assembly codes, fast mode decision, and fast inter-layer predictions to improve the performance of encoding speed. The experiment result shows that the proposed encoder can encode the test VGA/QVGA sequences in a speed up to 30 frames per second. In addition, the encoder can still maintain the video quality as single layer AVC encoder and not far away from JSVM 7.0.