Content Receiving Apparatus, Method of Controlling Video-Audio Output Timing and Content Providing System

A method of controlling a video-audio output timing, characterized by comprising:

• a decoding step of first receiving, from a content providing apparatus provided at an encoder side, a plurality of encoded video frames to which video time-stamps based on reference clock for the encoder side are attached and a plurality of encoded audio frames to which audio time-stamps based on a reference clock for the encoder side are attached, and then decoding the encoded video frames and the encoded audio frames in decoding means;
• storing step of storing, in storing means, a plurality of video frames obtained by decoding the encoded video frames in the decoding means and a plurality of audio frames obtained by decoding the encoded audio frames in the decoding means;
• difference calculating step of calculating, in calculating means, a time difference resulting from a gap between a clock frequency of a reference clock for the encoder side and a clock frequency of a system time clock for the decoder side;
• and
• timing-adjusting step of adjusting, in adjusting means, a timing of outputting the plurality of video frames, one by one, in accordance with the time difference and on the basis of a timing of outputting the plurality of audio frames, one by one.

A content providing system having a content providing apparatus and a content receiving apparatus, characterized in that the content providing apparatus comprises:

• encoding means for generating a plurality of encoded video frames to which video time-stamps based on reference clock for an encoder side are attached and a plurality of encoded audio frames to which audio time-stamps based on a reference clock are attached;
• and
• transmitting means for sequentially transmitting the plurality of encoded video frames and the plurality of encoded audio frames to the content receiving side, and
• the content receiving apparatus comprises:
• decoding means for receiving the plurality of encoded video frames to which video time-stamps are attached and the plurality of encoded audio frames to which audio time-stamps are attached from the content providing apparatus for an encoder side and for decoding the encoded video frames and the encoded audio frames;
• storing means for storing the plurality of video frames that the decoding means has obtained by decoding the encoded video frames and the plurality of audio frames that the decoding means has obtained by decoding the encoded audio frames;
• calculating means for calculating a time difference resulting from a gap between a clock frequency of a reference clock for the encoder side and a clock frequency of a system time clock for the decoder side;
• and
• timing-adjusting means for adjusting a timing of outputting the plurality of video frames, one by one, in accordance with the time difference and on the basis of a timing of outputting the plurality of audio frames, one by one.