Abstract: The present invention relates to a method and a device for monitoring the quality of video data having to undergo coding and decoding, making it possible to maintain predetermined constant quality of the video data after decoding. The method is such that information representing the complexity of video data to be coded is received from at least one coder. For each video-data item to be coded, a reference quantization value is calculated as a function of the complexity. For each video-data item to be coded, a reference throughput calculated as a function of the reference quantization value and of the value of the predetermined constant quality is calculated and transmitted to the coder, allowing the coder to code each video data item so as to obtain video data at the predetermined quality, after decoding.