A video codec system, a data processing method for processing data between the system and an external host system, and an encoding/decoding control method in the system are provided. The video codec system includes an encoder buffer; a decoder buffer; a task status register for writing the task statuses of the encoder, decoder, encoder buffer and decoder buffer; a command identification register for writing a command to be executed by the encoder and decoder; and an interface and control manager for parsing the command sent from the host system, writing the command in the command identification register, checking each task through the task status register, and then controlling the encoder and decoder through the command identification register. Therefore, the video codec system enhances the performance and reliability of the video code and makes the control of the encoding and decoding tasks easier.