A decoding apparatus for selectively decoding compressed video or audio signal included in a data signal. The decoding apparatus includes a demultiplexer that receives and separates a data signal from a compressed input signal. A video decoder and an audio decoder are provided to decode compressed video or audio signals stored in a decoder buffer. The decoding apparatus uses a memory to store the data signal separated by the demultiplexer, and a CPU to analyze the data signal stored in the memory. The CPU causes the data signal analyzed by the CPU to be stored in the decoder buffer if the analyzed data signal includes a compressed video signal or a compressed audio signal, and the compression method used for the compressed video signal or the compressed audio signal included in the data signal can be decoded by the video decoder or the audio decoder.