Adaptive estimation of frame time stamp latency
First Claim
1. A method comprising:
- capturing frames with a camera in a mobile device;
time stamping each frame after a latency period from when the frame is captured by the camera;
determining a vision based rotation of the camera using a pair of frames;
measuring a plurality of inertia based rotations using signals from an inertial sensor in the mobile device, wherein the signals are time stamped when produced by the inertial sensor and wherein measuring the plurality of inertia based rotations comprises integrating signals from the inertial sensor between start and stop times that correspond to times time stamped on each frame in the pair of frames and that are shifted with different delays;
determining an estimate of the latency period based on differences between the vision based rotation and each of the plurality of inertia based rotations; and
using the estimate of the latency period to correct for the latency period in time stamping of subsequently captured frames.
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Abstract
A mobile device compensates for a lack of a time stamp when an image frame is captured by estimating the frame time stamp latency. The mobile device captures images frames and time stamps each frame after the frame time stamp latency. A vision based rotation is determined from a pair of frames. A plurality of inertia based rotations is measured using time stamped signals from an inertial sensor in the mobile device based on different possible delays between time stamping each frame and time stamps on the signals from the inertial sensors. The determined rotations may be about the camera'"'"'s optical axis. The vision based rotation is compared to the plurality of inertia based rotations to determine an estimated frame time stamp latency, which is used to correct the frame time stamp latency when time stamping subsequently captured frames. A median latency determined using different frame pairs may be used.
7 Citations
30 Claims
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1. A method comprising:
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capturing frames with a camera in a mobile device; time stamping each frame after a latency period from when the frame is captured by the camera; determining a vision based rotation of the camera using a pair of frames; measuring a plurality of inertia based rotations using signals from an inertial sensor in the mobile device, wherein the signals are time stamped when produced by the inertial sensor and wherein measuring the plurality of inertia based rotations comprises integrating signals from the inertial sensor between start and stop times that correspond to times time stamped on each frame in the pair of frames and that are shifted with different delays; determining an estimate of the latency period based on differences between the vision based rotation and each of the plurality of inertia based rotations; and using the estimate of the latency period to correct for the latency period in time stamping of subsequently captured frames. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A mobile device comprising:
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a camera; an inertial sensor; and a processor coupled to receive frames captured by the camera and coupled to sample signals from the inertial sensor, wherein the frames are time stamped after a latency period from when the frame is captured by the camera and the signals from the inertial sensor are time stamped when produced by the inertial sensor, the processor configured to determine a vision based rotation of the camera using a pair of frames, measure a plurality of inertia based rotations using the signals sampled from the inertial sensor, wherein the plurality of inertia based rotations being measured by integrating signals from the inertial sensor between start and stop times that correspond to times time stamped on each frame in the pair of frames and that are shifted with different delays, determine an estimate of the latency period based on differences between the vision based rotation and each of the plurality of inertia based rotations, and use the estimate of the latency period to correct for the latency period in time stamping of subsequently captured frames. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A mobile device comprising:
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means for capturing frames of images or video; means for time stamping each frame after a latency period from when the frame is captured; means for determining a vision based rotation using a pair of frames; means for measuring a plurality of inertia based rotations using signals from an inertial sensor in the mobile device, wherein the signals are time stamped when produced by the inertial sensor and wherein measuring the plurality of inertia based rotations comprises integrating signals from the inertial sensor between start and stop times that correspond to times time stamped on each frame in the pair of frames and that are shifted with different delays; means for determining an estimate of the latency period based on differences between the vision based rotation and each of the plurality of inertia based rotations; and means for using the estimate of the latency period to correct for the latency period in subsequently captured frames. - View Dependent Claims (22, 23, 24, 25)
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26. A non-transitory computer-readable medium including program code stored thereon, comprising:
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program code to determine a vision based rotation of a camera using a pair of frames captured by the camera, wherein each frame is time stamped after a latency period from when the frame is captured by the camera; program code to measure a plurality of inertia based rotations using signals sample from an inertial sensor, wherein the signals are time stamped when produced by the inertial sensor and the plurality of inertia based rotations are measured by integrating signals from the inertial sensor between start and stop times that correspond to times time stamped on each frame in the pair of frames and that are shifted with different delays; program code to determine an estimate of the latency period based on differences between the vision based rotation and each of the plurality of inertia based rotations; and program code to use the estimate of the latency period to correct the latency period in subsequently captured frames. - View Dependent Claims (27, 28, 29, 30)
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Specification