A data recording and reproduction apparatus is provided with a stream attribute decision means for deciding whether an audio data stream supplied from an outside source is compressed or not. A compression ID flag having a value according to the result of the compression decision is attached to the audio data stream, and the flag-attached audio data stream is written in a stream storage unit. Therefore, a watermark can be inserted in a compressed audio data stream after reading the compressed audio data stream from the stream storage unit, whereby the time required for writing the compressed audio data stream in the stream storage unit is reduced, and the quality of analog audio data obtained by reproducing the compressed audio data stream is prevented from being degraded.