Method for transmitting audio and video under environment of network with different speeds

The invention discloses a method for transmitting audio and video under an environment of a network with different speeds applied in a multimedia communication system which at least comprises a data transmitting terminal and a data receiving terminal. The data transmitting terminal at least comprises an encoder, a data buffering and a first control logic, and the data receiving terminal controls the encoder through the first control logic according to the buffer filling degree of the data buffering and selects the source code rate of a content source. The method can be used for automatically detecting the actual data transmitting speed so that the encoding code rate of the audio and video is suitable for the changing network environment and the actual data transmitting speed, therefore, a user enjoys the optimal multimedia quality under the changing network environment.