1. Field of the Invention
The present invention relates to an audio playback/recording apparatus, and more particularly to an audio playback/recording apparatus, which performs playback and recording of audio data, and which can record audio data into an external memory or transfer audio data via a general-purpose interface, and which also performs processing related to the protection of digital audio data.
2. Related Art
In an apparatus capable of recording and playback of audio data (including music data), because of the ease of use of compact personal media such as memory cards, widespread growth is being seen in the usage of these media as an external storage medium for a personal computer or portable terminal or the like.
In the field of digital audio as well, these media are gaining attention as the next generation of mechanism-free, vibration-immune recording medium.
In comparison with such recording media as DAT (digital audio tape) and MD (MiniDisc), however, because these media are not superior in terms of cost performance, there is a need for a medium capable of achieving high quality and compressed recording.
In the Japanese Patent Publication (KOKAI) No. 9-73299, there is a disclosure of an MPEG audio playback/recording apparatus capable of playing back easy to hear audio, even with varying playback speed, for audio data subjected to compression and decompression according the MPEG (Moving Picture Expert Group) standard. This apparatus is a dedicated playback apparatus, and requires an external controller such as a microcomputer.
In the Japanese Patent Publication (KOKAI) No. 10-320000, there is a disclosure of a portable audio recording/playback apparatus that performs recording and playback, executing MPEG compression and decompression in real time under microcomputer control.
In the Japanese Patent Publication (KOKAI) No. 7-325600, there is a disclosure of a portable audio recording/playback apparatus having an IC memory card.
The above-noted prior art, however, has the following problems.
The first problem is that it is not possible to accommodate diverse audio data compression systems.
The second problem is that it is not possible to accommodate encryption accompanying the shift to digital audio.
Accordingly, it is an object of the present invention to provide an audio playback/recording apparatus having a means capable of accommodating different types of compression and decompression of audio data, and a means capable of encryption and decryption of digital audio data, and also certification means.