A transmission apparatus comprising: an encoded data reception unit that receives encoded data including an audio clock master switch (ACMSW) packet from a reception apparatu: via a first, bidirectional, physical channel; an audio clock generator that generates an audio clock on the basis of a carrier recovered from the received encoded data; and an audio data transmission unit (305, 306) that transmits audio data via a second, unidirectional, physical channel to the reception apparatus in synchronization with the generated audio clock, wherein the audio clock generator generates the audio clock by firstly generating a video clock based on the carrier clock (311a, 311b) and secondly dividing the generated video clock on the basis of dividing ratio information obtained from the audio clock master switch (ACMSW) packet of the received encoded data (311c, 311d, 311e), wherein the dividing ratio information comprises a first value (Naud) and a second value (Maud), the first value being a count interval of the audio clock and the second value being a count value of the video clock at the count interval, wherein the audio clock generator generates the audio clock and the audio data transmission unit (305, 306) transmits the audio data to the reception apparatus in synchronization with the generated audio clock when a request for using the audio clock generated on the basis of the recovered carrier clock is obtained from the audio clock master switch (ACMSW) packet received from the reception apparatus, and wherein, on receiving the request and determining that the request can be handled, the transmission apparatus transmits an acknowledgement via the first physical channel to the reception apparatus. an encoded data reception unit that receives encoded data including an audio clock master switch (ACMSW) packet from a reception apparatu: via a first, bidirectional, physical channel; an audio clock generator that generates an audio clock on the basis of a carrier recovered from the received encoded data; and an audio data transmission unit (305, 306) that transmits audio data via a second, unidirectional, physical channel to the reception apparatus in synchronization with the generated audio clock, wherein the audio clock generator generates the audio clock by firstly generating a video clock based on the carrier clock (311a, 311b) and secondly dividing the generated video clock on the basis of dividing ratio information obtained from the audio clock master switch (ACMSW) packet of the received encoded data (311c, 311d, 311e), wherein the dividing ratio information comprises a first value (Naud) and a second value (Maud), the first value being a count interval of the audio clock and the second value being a count value of the video clock at the count interval, wherein the audio clock generator generates the audio clock and the audio data transmission unit (305, 306) transmits the audio data to the reception apparatus in synchronization with the generated audio clock when a request for using the audio clock generated on the basis of the recovered carrier clock is obtained from the audio clock master switch (ACMSW) packet received from the reception apparatus, and wherein, on receiving the request and determining that the request can be handled, the transmission apparatus transmits an acknowledgement via the first physical channel to the reception apparatus.