Patent ID: 7502417

Claim:
A data transmission device for generating a plurality of compressed/encoded data of different bit rates from a single video signal and simultaneously transmitting the compressed/encoded data onto a network, comprising: a synchronizing signal detection section for detecting a vertical synchronizing signal and a color synchronizing signal from the video signal input thereto, wherein the video signal comprises an NTSC composite signal; a plurality of compressing/encoding sections for compressing/encoding the video signal to generate data streams of different bit rates, respectively, wherein the compressing/encoding sections generate data streams having the same sequence of picture types; a timing control section for controlling said compressing/encoding sections in accordance with the detected synchronizing signal such that timings for starting compression/encoding processes in said compressing/encoding sections are shifted from one another in units of frame; and a multiplexing section for sequentially multiplexing the data streams generated respectively by said compressing/encoding sections and transmitting the multiplexed data onto the network, wherein the timing control section causes one of said compressing/encoding sections to start the compression/encoding process when frame start timing of the video signal derived based on the vertical synchronizing signal coincides with rise timing of a chrominance subcarrier signal synchronized with the color synchronizing signal, and causes a different one of said compressing/encoding sections to start the compression/encoding process when the frame start timing coincides thereafter with fall timing of the chrominance subcarrier signal.