Data processing system and method

A data processing apparatus, comprising:

• a stream decoder for decrypting a stream encrypted by broadcast encryption to obtain a first decrypted stream;
• first, second, and third temporary store buffers;
• a first direct memory access controller for the stream decoder for controlling data transfer between the stream decoder and the first temporary store buffer;
• an encryption/decryption processor for decrypting a stream encrypted by content encryption to obtain a second decrypted stream and storing the second decrypted stream in the first temporary store buffer, the encryption/decryption processor reading one of the first and second decrypted streams from the second temporary store buffer, encrypting the read-out stream by content encryption;
• a stream converter for performing format conversion between a transport stream and a program stream and outputting the converted stream;
• a PCI-bus controller for controlling an input and output of a PCI-bus;
• a second direct memory access controller for the PCI-bus controller for controlling data transfer between the PCI-bus and the third temporary store buffer;
• fourth, fifth, and sixth temporary store buffers corresponding to the first, second, third temporary store buffers, respectively;
• a memory interface for receiving and outputting data between the fourth to sixth temporary store buffers and an external memory;
• and
• an overflow monitor, wherein:
• the first temporary store buffer stores the first decrypted stream and the second decrypted stream,
• the second temporary store buffer stores a stream transferred from the first temporary store buffer,
• the third temporary store buffer stores the converted stream and the stream encrypted in the encryption/decryption processor, and
• when there is a possibility of overflow of any of the first to third temporary store buffers, the overflow monitor performs control such that writing in the temporary store buffer that may be overflowed is stopped and the stream converter performs processing while performing data transfer to/from an external memory through one of the forth to sixth temporary store buffers.