To easily obtain video images of good image quality by encoding processing by 2-path encoding system.

In encoding processing 101, input video data D1 is encoded by a fixed quantization step. In a determination processing 102, a target data amount is determined as target data amount for every picture so that the target data amount is approximately proportional to the amount of generated data and the total sum of the target data amount becomes a fixed capacity. In encoding processing 103, input video data D1 is encoded by the fixed quantization step, the quantization step is the one for generating each determined target data amount. In evaluation processing 104, the image quality of the video data D2 to which encoding processing 103 is applied is evaluated, a part where the image quality of the video data D2 is deteriorated is specified, and the part is re-encoded based on the new target data amount. This invention is applicable to an authoring device.