Patent ID: 7801213

Claim:
A method for modifying a data rate of a video signal, comprising: receiving a compressed video signal; providing a closed-loop transrating path for modifying a data rate of the video signal; providing an open-loop transrating path for modifying the data rate of the video signal; automated selecting of one of said open-loop transrating path or said closed-loop transrating path for modifying the data rate of at least a portion of said video signal; said closed-loop transrating path and said open loop transrating path are operable simultaneously and are adapted to accept at least different portions of said video signal; and providing pixel quantization error control in said closed loop transrating path, said pixel quantization error control comprising: obtaining errors from quantization of transformation coefficients of incoming pixels of the video signal; deriving pixel errors from said quantization errors; storing said pixel errors; retrieving said stored pixel errors during modification of said data rate of associated pixels; deriving error correction quantization data from said retrieved pixel errors; and applying said error correction quantization data in order to prevent accumulation of requantization artifacts during said modification of said data rate of said associated pixels; wherein: said closed-loop transrating path is selected for modifying the data rate of I-frames and P-frames of said video signal; said open-loop transrating path is selected for modifying the data rate of B-frames of said video signal; in the event that at least one of: (a) the open-loop transrating path is idle; and (b) the closed-loop path is oversubscribed, the open-loop transrating path is selected for modifying the data rate of I-frames and P-frames of the video signal without said pixel quantization error control; and in the event that at least one of: (a) the closed-loop transrating path is idle; and (b) the open-loop path is oversubscribed, selecting the closed-loop transrating path for modifying the data rate of B-frames.