Patent ID: 8811472

Claim:
A bitrate control device for controlling bitrate of video data, the device comprising a processor, and the processor being operable to function as: a setting module that sets, for each frame in the video data, a target code amount to be used in encoding the frame by an encoding module for maintaining a given bitrate; an adjusting module that adjusts the target code amount set by the setting module based on given information; and a managing module that is configured to perform: saving a code amount corresponding to an amount reduced in the target code amount by the adjusting module in a virtual storage management buffer having a given upper limit, when the adjusting module adjusts to reduce the target code amount; and withdrawing a code amount corresponding to an amount increased in the target code amount by the adjusting module from the virtual storage management buffer, when the adjusting module adjusts to increase the target code amount, wherein the managing module comprises an excess withdrawing module that withdraws a code amount from the virtual storage management buffer for an amount exceeding the code amount that is currently stored in the virtual storage management buffer and being within a given limit amount, wherein the setting module sets the target code amount for each frame while considering a group of frames as a processing unit, the group of frames containing a given number of frames, and wherein the managing module saves in the virtual storage management buffer, when the adjusting module adjusts to reduce the target code amount, a code amount Y as the amount reduced in the target code amount by the adjusting module, the code amount Y being obtained by the following calculation: Y =Rest−Rest× Fk where Rest is a code amount assigned to all frames in the group of frames except a subject frame subjected to adjusting the target code amount therefore, and where Fk is a reduction factor of the corrected target code amount with respect to the uncorrected target code amount.