Low latency cadence detection for frame rate conversion
View Patent ↗A receiver is configured to receive video frames. A cadence detector is in communication with the receiver and is configured to analyze a newly received video frame to determine the cadence of the video frames. A frame rate converter is configured to interpolate at least two of the video frames to form output frames in accordance with an interpolation parameter based on the cadence and with a frequency scaling factor. The frequency scaling factor corresponds to the frame rate of the output frames.
1. A method, comprising:
receiving a plurality of video frames;
adjusting an interpolation parameter based on detecting a cadence of the plurality of video frames; and
interpolating at least two of the plurality of video frames that were received based on the interpolation parameter and a frequency scaling factor to form a plurality of output frames, the frequency scaling factor corresponding to a frame rate for the plurality of output frames.
2. The method of claim 1 , further comprising analyzing a newly received video frame to determine the cadence of the plurality of video frames.
3. The method of claim 2 , wherein the interpolating is performed prior to a completion of the analyzing.
4. The method of claim 1 , further comprising receiving an indicator of the cadence from an upstream video processor.
5. The method of claim 4 , wherein the interpolation parameter indicates a position in fractional fourths relative to two of the plurality of video frames when the indicator of the cadence corresponds to a 2:2 pull-down pattern.
6. The method of claim 1 , wherein the at least two of the plurality of video frames are chosen based on the cadence.
7. The method of claim 1 , wherein the interpolation parameter identifies a position of at least one of the plurality of output frames relative to two of the plurality of video frames.
8. The method of claim 1 , wherein detecting the cadence comprises comparing a first one of the plurality of video frames to a second one of the plurality of video frames.
9. The method of claim 1 , wherein the interpolating produces the plurality of output frames at twice the frame rate at which the plurality of video frames are received.
10. The method of claim 1 , wherein the interpolation parameter indicates a position in fractional fifths relative to two of the plurality of video frames when the cadence corresponds to a 3:2 pull-down pattern.
11. The method of claim 1 , wherein the interpolation parameter indicates motion in fractional halves between at least a subset of the plurality of video frames responsive to a change in the cadence from a 3:2 pull-down pattern.
12. The method of claim 1 , wherein the cadence comprises a 3:2 pull-down pattern and the interpolating introduces a delay corresponding to a time for 1.5 buffered frames of the plurality of video frames, wherein the delay is positioned after receiving one of the plurality of video frames and before forming one of the plurality of output frames.
13. A video device comprising:
a receiver configured to receive a plurality of video frames;
a cadence detector in communication with the receiver, the cadence detector configured to analyze a newly received video frame to determine a cadence of the plurality of video frames; and
a frame rate converter configured to interpolate at least two of the plurality of video frames to form a plurality of output frames in accordance with an interpolation parameter based on the cadence and with a frequency scaling factor, the frequency scaling factor corresponding to a frame rate of the plurality of output frames.
14. The video device of claim 13 , wherein the cadence detector compares the newly received video frame to one of the plurality of video frames to determine the cadence.
15. The video device of claim 13 , wherein the interpolation parameter identifies a position of at least one of the plurality of output frames relative to two of the plurality of video frames.
16. The video device of claim 15 , wherein the frame rate converter produces the plurality of output frames at twice the frame rate at which the plurality of video frames are received.
17. The video device of claim 16 , wherein when the cadence comprises a 3:2 pull-down pattern, and the interpolation parameter indicates the position in fractional fifths relative to two of the plurality of video frames.
18. The video device of claim 17 , wherein when the cadence detector detects a change in the cadence from a 3:2 pull-down pattern, and the interpolation parameter indicates motion in fractional halves between a first one of the plurality of video frames and a second one of the plurality of video frames.
19. The video device of claim 16 , wherein when the cadence comprises a 2:2 pull-down pattern, and the interpolation parameter indicates the position in fractional fourths relative to two of the plurality of video frames.
20. A display device comprising:
a receiver configured to receive a plurality of video frames;
a cadence detector in communication with the receiver, the cadence detector configured to analyze a newly received video frame to determine a cadence of the plurality of video frames;
a frame rate converter for interpolating at least two of the plurality of video frames to form a plurality of output frames in accordance with an interpolation parameter based on the cadence and with a frequency scaling factor, the frequency scaling factor corresponding to a frame rate of the plurality of output frames; and
a display in communication with the frame rate converter, the display configured to receive the plurality of output frames.