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* 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 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
#ifdef __cplusplus
extern "C" {
/*!\cond */
// TODO(any): These two variables are only used in avx2, sse2, sse4
// implementations, where the block size is still hard coded. This should be
// fixed to align with the c implementation.
#define BH 32
#define BW 32
// Block size used in temporal filtering.
// Window size for temporal filtering.
// Hyper-parameters used to compute filtering weight. These hyper-parameters can
// be tuned for a better performance.
// 0. A scale factor used in temporal filtering to raise the filter weight from
// `double` with range [0, 1] to `int` with range [0, 1000].
#define TF_WEIGHT_SCALE 1000
// 1. Weight factor used to balance the weighted-average between window error
// and block error. The weight is for window error while the weight for block
// error is always set as 1.
// 2. Threshold for using q to adjust the filtering weight. Concretely, when
// using a small q (high bitrate), we would like to reduce the filtering
// strength such that more detailed information can be preserved. Hence, when
// q is smaller than this threshold, we will adjust the filtering weight
// based on the q-value.
// 3. Normalization factor used to normalize the motion search error. Since the
// motion search error can be large and uncontrollable, we will simply
// normalize it before using it to compute the filtering weight.
// 4. Threshold for using `arnr_strength` to adjust the filtering strength.
// Concretely, users can use `arnr_strength` arguments to control the
// strength of temporal filtering. When `arnr_strength` is small enough (
// i.e., smaller than this threshold), we will adjust the filtering weight
// based on the strength value.
// 5. Threshold for using motion search distance to adjust the filtering weight.
// Concretely, larger motion search vector leads to a higher probability of
// unreliable search. Hence, we would like to reduce the filtering strength
// when the distance is large enough. Considering that the distance actually
// relies on the frame size, this threshold is also a resolution-based
// threshold. Taking 720p videos as an instance, if this field equals to 0.1,
// then the actual threshold will be 720 * 0.1 = 72. Similarly, the threshold
// for 360p videos will be 360 * 0.1 = 36.
// Estimates noise level from a given frame using a single plane (Y, U, or V).
// This is an adaptation of the mehtod in the following paper:
// Shen-Chuan Tai, Shih-Ming Yang, "A fast method for image noise
// estimation using Laplacian operator and adaptive edge detection",
// Proc. 3rd International Symposium on Communications, Control and
// Signal Processing, 2008, St Julians, Malta.
// Inputs:
// frame: Pointer to the frame to estimate noise level from.
// plane: Index of the plane used for noise estimation. Commonly, 0 for
// Y-plane, 1 for U-plane, and 2 for V-plane.
// bit_depth: Actual bit-depth instead of the encoding bit-depth of the frame.
// Returns:
// The estimated noise, or -1.0 if there are too few smooth pixels.
double av1_estimate_noise_from_single_plane(const YV12_BUFFER_CONFIG *frame,
const int plane,
const int bit_depth);
#define TF_QINDEX 128 // Q-index used in temporal filtering.
/*!\endcond */
/*!\brief Performs temporal filtering if needed on a source frame.
* For example to create a filtered alternate reference frame (ARF)
* In this function, the lookahead index is different from the 0-based
* real index. For example, if we want to filter the first frame in the
* pre-fetched buffer `cpi->lookahead`, the lookahead index will be -1 instead
* of 0. More concretely, 0 indicates the first LOOKAHEAD frame, which is the
* second frame in the pre-fetched buffer. Another example: if we want to filter
* the 17-th frame, which is an ARF, the lookahead index is 15 instead of 16.
* Futhermore, negative number is used for key frame in one-pass mode, where key
* frame is filtered with the frames before it instead of after it. For example,
* -15 means to filter the 17-th frame, which is a key frame in one-pass mode.
* \ingroup src_frame_proc
* \param[in] cpi Top level encoder instance structure
* \param[in] filter_frame_lookahead_idx The index of the to-filter frame in
* the lookahead buffer cpi->lookahead.
* \param[in,out] show_existing_arf Whether to show existing ARF. This
* field is updated in this function.
* \return Whether temporal filtering is successfully done.
int av1_temporal_filter(AV1_COMP *cpi, const int filter_frame_lookahead_idx,
int *show_existing_arf);
#ifdef __cplusplus
} // extern "C"