Apparatus having corresponding methods, computer-readable media, and data structures comprise an input circuit adapted to receive a stream of delta-encoded data; a record circuit adapted to store the stream of delta-encoded data in a stream file; a current frame circuit adapted to maintain a current frame of the data based on the stream of delta-encoded data; a record frame circuit adapted to store the current frame in a frame file as an intraframe with a frame pointer at a plurality of different index times, wherein each frame pointer indicates a location in the stream file associated with the respective index time; and a record index circuit adapted to store the index times sequentially in an index file, and adapted to store an index pointer for each index time, wherein each index pointer indicates a location in the frame file of the intraframe associated with the respective index time.