aomedia / aom / d3e5dbc183f5f0b2d4dc5af68e1f4804b36cf787 / . / aom_dsp / flow_estimation / disflow.h

/* | |

* Copyright (c) 2016, Alliance for Open Media. All rights reserved | |

* | |

* This source code is subject to the terms of the BSD 2 Clause License and | |

* the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License | |

* was not distributed with this source code in the LICENSE file, you can | |

* obtain it at www.aomedia.org/license/software. If the Alliance for Open | |

* Media Patent License 1.0 was not distributed with this source code in the | |

* PATENTS file, you can obtain it at www.aomedia.org/license/patent. | |

*/ | |

#ifndef AOM_AOM_DSP_FLOW_ESTIMATION_DISFLOW_H_ | |

#define AOM_AOM_DSP_FLOW_ESTIMATION_DISFLOW_H_ | |

#include <stdbool.h> | |

#include "aom_dsp/flow_estimation/flow_estimation.h" | |

#include "aom_dsp/rect.h" | |

#include "aom_scale/yv12config.h" | |

#ifdef __cplusplus | |

extern "C" { | |

#endif | |

// Number of pyramid levels in disflow computation | |

#define DISFLOW_PYRAMID_LEVELS 12 | |

// Size of square patches in the disflow dense grid | |

// Must be a power of 2 | |

#define DISFLOW_PATCH_SIZE_LOG2 3 | |

#define DISFLOW_PATCH_SIZE (1 << DISFLOW_PATCH_SIZE_LOG2) | |

// Center point of square patch | |

#define DISFLOW_PATCH_CENTER ((DISFLOW_PATCH_SIZE / 2) - 1) | |

// Overall scale of the `dx`, `dy` and `dt` arrays in the disflow code | |

// In other words, the various derivatives are calculated with an internal | |

// precision of (8 + DISFLOW_DERIV_SCALE_LOG2) bits, from an 8-bit input. | |

// | |

// This must be carefully synchronized with the code in sobel_filter() | |

// (which fills the dx and dy arrays) and compute_flow_error() (which | |

// fills dt); see the comments in those functions for more details | |

#define DISFLOW_DERIV_SCALE_LOG2 3 | |

#define DISFLOW_DERIV_SCALE (1 << DISFLOW_DERIV_SCALE_LOG2) | |

// Scale factor applied to each step in the main refinement loop | |

// | |

// This should be <= 1.0 to avoid overshoot. Values below 1.0 | |

// may help in some cases, but slow convergence overall, so | |

// will require careful tuning. | |

// TODO(rachelbarker): Tune this value | |

#define DISFLOW_STEP_SIZE 1.0 | |

// Step size at which we should terminate iteration | |

// The idea here is that, if we take a step which is much smaller than 1px in | |

// size, then the values won't change much from iteration to iteration, so | |

// many future steps will also be small, and that won't have much effect | |

// on the ultimate result. So we can terminate early. | |

// | |

// To look at it another way, when we take a small step, that means that | |

// either we're near to convergence (so can stop), or we're stuck in a | |

// shallow valley and will take many iterations to get unstuck. | |

// | |

// Solving the latter properly requires fancier methods, such as "gradient | |

// descent with momentum". For now, we terminate to avoid wasting a ton of | |

// time on points which are either nearly-converged or stuck. | |

// | |

// Terminating at 1/8 px seems to give good results for global motion estimation | |

#define DISFLOW_STEP_SIZE_THRESOLD (1. / 8.) | |

// Max number of iterations if warp convergence is not found | |

#define DISFLOW_MAX_ITR 4 | |

// Internal precision of cubic interpolation filters | |

// The limiting factor here is that: | |

// * Before integerizing, the maximum value of any kernel tap is 1.0 | |

// * After integerizing, each tap must fit into an int16_t. | |

// Thus the largest multiplier we can get away with is 2^14 = 16384, | |

// as 2^15 = 32768 is too large to fit in an int16_t. | |

#define DISFLOW_INTERP_BITS 14 | |

typedef struct { | |

// x and y directions of flow, per patch | |

double *u; | |

double *v; | |

// Sizes of the above arrays | |

int width; | |

int height; | |

int stride; | |

} FlowField; | |

bool av1_compute_global_motion_disflow(TransformationType type, | |

YV12_BUFFER_CONFIG *src, | |

YV12_BUFFER_CONFIG *ref, int bit_depth, | |

MotionModel *motion_models, | |

int num_motion_models); | |

#ifdef __cplusplus | |

} | |

#endif | |

#endif // AOM_AOM_DSP_FLOW_ESTIMATION_DISFLOW_H_ |