Method for video transcoding with adaptive frame rate control
AssigneeInternational Business Machines Corporation
InventorsLigang Lu, Shan Liu
Life of this patent
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Abstract
A video transcoding method is provided for transcoding a first signal stream compressed by a first coding scheme to a second signal stream compressed by a second coding scheme. The method employs an adaptive frame rate and a joint temporal-spatial rate control technique, such that the overall quality of compressed MPEG video can be significantly enhanced when the transcoding is controlled in the joint temporal (picture or frame rate) and spatial (quantization) domains. One embodiment considers transcoding from high bit rate video with larger image size (e.g. 4CIF/4SIF, CIF) coded by one coding technique, e.g., MPEG-2 to a lower bit rate video with smaller image size (e.g. CIF, QCIF) coded by the same or another coding technique, e.g., MPEG-4.
Claims10
A method for transcoding an input compressed video signal stream to an output compressed signal stream comprising:
- a) performing adaptive frame rate transcoding for a sub-GOP (Group of Pictures), said sub-GOP comprising one or more types of frames of said input compressed signal stream to be transcoded;
- and,
- b) using a joint temporal-spatial rate distortion optimization within said sub-GOP to adjust the output rate of the compressed output signal stream, wherein for said sub-GOP, said joint temporal-spatial rate distortion optimization comprises:
- determining which frames of said sub-GOP to be either skipped or transcoded;
- computing a rate-distortion contribution resulting from each transcoded frame and from each skipped frame;
- and,
- minimizing a total distortion for a target rate of said compressed output signal stream based on said transcoded frame and skipped frame rate-distortion contributions.
Dependencies are inferred from the claim text.