Patent ID: 7697816
Filing Date: 2010-04-13
Classification: H04N

Abstract:
1. A circulating memory apparatus for recording each time series input video data in a circulating memory area for each channel secured in a disk of a recording device of the circulating memory apparatus, comprising: a buffer for receiving and buffering the each time series input video data for each channel; an editing unit for reading, from the buffer, a plurality of image frames of the time series input video data for the same one channel, making a subblock based on the read image frames, and editing a data block having a predetermined data size including a plurality of subblocks; a writing unit for writing said each time series input video data by data block into the circulating memory area for each channel in the disk of said recording device; a cache memory which includes a plurality of cache areas each of which corresponds to a specific image frame output request for outputting a specific image frame for a specific channel of the each time series input video data; an outputting unit for reading the time series input video data, by subblock, containing the specific image frame from the circulating memory area for the specific channel in the disk of said recording device in response to the specific data output request and for selectively outputting the specific image frame contained in a subblock of the subblocks; and a cache area management table, corresponding to each of the plurality of cache areas, for indicating information on the subblock outputted to the cache area and index information on the image frame, wherein the data block has a header portion and the plurality of subblocks and has a predetermined block data size equal to an integer multiple of a data size of a sector of the disk in said recording device, wherein the header portion of the data block has header information which indicates a frame number of a start image frame contained in the data block, a sector identifier indicating a start position of the subblock contained in the data block, and the number of the image frames contained in the data block, wherein the subblock includes an internal header portion and a data portion, the data portion follows the internal header portion and is configured to continuously pack the plurality of image frames, wherein the subblock further includes a data vacant portion which is arranged to follow a final image frame contained in the subblock and a length of the vacant portion is adjusted so that a data size of the subblock is equal to an integer multiple of the size of the sector of the disk in the recording device, wherein the outputting unit selectively executes a first reading mode or a second reading mode, the first reading mode is an operation for reading the video data, by subblock, from the memory area and outputting it, and the second reading mode is an operation for reading the video data, by data block, from the memory area and selectively outputting the specific image frame contained in the data block, wherein, in the first reading mode, based on the cache area management table, the outputting unit determines whether or not a target subblock of the subblocks which contains the specific image data which is requested by the specific data output request is stored in a specific cache area of the cache memory, and wherein if the target subblock is not stored in the specific cache area of the cache memory, then the outputting unit reads the subblock containing the specific image frame from the memory area of the specific channel to the specific cache area.