Method for controlling code rate in distributed video coding

The invention discloses a method for controlling the code rate in distributed video coding. The discrete cosine coefficient difference values between an original frame and the same position blocks between the adjacent key frame in front of the original frame and the adjacent key frame behind the original frame are respectively calculated at the coding end, the discrete cosine coefficient difference values are compared with a preset threshold value to obtain the classification information values, and then the position blocks are judged to be in the slow movement mode or the strenuous movement mode. The code rate which needs to be transmitted by the coding end is estimated according to the different movement modes of the macro blocks, and the efficiency of distributed video coding is improved. The code rate is adjusted in real time in a correlation noise modeling (CNM) through Laplace parameters with the block level and the frame level switched with each other, and under the condition that the transmission of the small code rate is ensured, decoding complexity can be lowered to the maximum extent, and a decoder can conduct decoding correctly.