METHOD OF ENCODING VIDEO WITH FILM GRAIN
A system for providing improved video quality and compression efficiency during encoding by detecting video segments having film grain approaching the “Red Lady” problem. The system detects when film grain approaches the level of the “Red Lady” problem by measuring frame-by-frame temporal differences (ME scores). From the ME scores, two key indicators are identified: (1) The average temporal difference in frames with an intermediate motion level higher than frames of non-noisy video; and (2) The fluctuation of the temporal differences between frames in a group is very small. When these indicators identify a high film video, a signal is provided to an encoder which allocates less bits to I frames and more bits to P and B frames than for other frames of video without comparable film grain.
1 . A method for encoding video comprising:
receiving video frames from an encoder configured to compresses the video frames;
receiving motion estimation (ME) data for the video frames;
calculating a ME score for the video frames, wherein the ME score indicates a measurement of plotted frame-by-frame temporal differences;
calculating an ME stability value measuring a statistical measure of the ME score over time;
providing a high film grain indication signal to the encoder indicating a particular group of the video frames contains high film grain when the ME score for the segment exceeds a first threshold and the ME stability value for the segment is below a second threshold,
wherein when the high film grain indication signal is provided, the encoder compresses the video frames by allocating less bits to I frames and more bits to P and B type frames than to other frames of the video.
2 . The method of claim 1 , wherein when the high film grain indication is not provided, the encoder allocates more bits to the I frame than when the high film grain indication is provided.
3 . The method of claim 1 , wherein the first threshold is greater than 20.