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| 1 /* |
| 2 * Copyright (c) 2016 The WebRTC project authors. All Rights Reserved. |
| 3 * |
| 4 * Use of this source code is governed by a BSD-style license |
| 5 * that can be found in the LICENSE file in the root of the source |
| 6 * tree. An additional intellectual property rights grant can be found |
| 7 * in the file PATENTS. All contributing project authors may |
| 8 * be found in the AUTHORS file in the root of the source tree. |
| 9 */ |
| 10 |
| 11 #include "webrtc/modules/video_processing/util/noise_estimation.h" |
| 12 |
| 13 namespace webrtc { |
| 14 |
| 15 void NoiseEstimation::Init(int width, int height, CpuType cpu_type) { |
| 16 int mb_cols = width >> 4; |
| 17 int mb_rows = height >> 4; |
| 18 consec_low_var_.reset(new uint32_t[mb_cols * mb_rows]()); |
| 19 width_ = width; |
| 20 height_ = height; |
| 21 mb_cols_ = width_ >> 4; |
| 22 mb_rows_ = height_ >> 4; |
| 23 cpu_type_ = cpu_type; |
| 24 } |
| 25 |
| 26 void NoiseEstimation::GetNoise(int mb_index, uint32_t var, uint32_t luma) { |
| 27 consec_low_var_[mb_index]++; |
| 28 num_static_block_++; |
| 29 if (consec_low_var_[mb_index] >= kConsecLowVarFrame && |
| 30 (luma >> 8) < kAverageLumaMax && (luma >> 8) > kAverageLumaMin) { |
| 31 // Normalized var by the average luma value, this gives more weight to |
| 32 // darker blocks. |
| 33 int nor_var = var / (luma >> 12); |
| 34 noise_var_ += |
| 35 nor_var > kBlockSelectionVarMax ? kBlockSelectionVarMax : nor_var; |
| 36 num_noisy_block_++; |
| 37 } |
| 38 } |
| 39 |
| 40 void NoiseEstimation::ResetConsecLowVar(int mb_index) { |
| 41 consec_low_var_[mb_index] = 0; |
| 42 } |
| 43 |
| 44 void NoiseEstimation::UpdateNoiseLevel() { |
| 45 // TODO(jackychen): Tune a threshold for numb_noisy_block > T to make the |
| 46 // condition more reasonable. |
| 47 // No enough samples implies the motion of the camera or too many moving |
| 48 // objects in the frame. |
| 49 if (num_static_block_ < (0.65 * mb_cols_ * mb_rows_) || !num_noisy_block_) { |
| 50 noise_var_ = 0; |
| 51 noise_var_accum_ = 0; |
| 52 num_static_block_ = 0; |
| 53 num_noisy_block_ = 0; |
| 54 #if DISPLAY |
| 55 printf("Not enough samples.\n"); |
| 56 #endif |
| 57 return; |
| 58 } else { |
| 59 // Normalized by the number of noisy blocks. |
| 60 noise_var_ /= num_noisy_block_; |
| 61 // Get the percentage of static blocks. |
| 62 percent_static_block_ = |
| 63 static_cast<double>(num_static_block_) / (mb_cols_ * mb_rows_); |
| 64 #if DISPLAY |
| 65 printf("%d %d fraction = %.3f\n", num_static_block_, mb_cols_ * mb_rows_, |
| 66 percent_static_block_); |
| 67 #endif |
| 68 num_noisy_block_ = 0; |
| 69 num_static_block_ = 0; |
| 70 } |
| 71 // For the first frame just update the value with current noise_var_, |
| 72 // otherwise, use the averaging window. |
| 73 if (noise_var_accum_ == 0) { |
| 74 noise_var_accum_ = noise_var_; |
| 75 } else { |
| 76 noise_var_accum_ = (noise_var_accum_ * 15 + noise_var_) / 16; |
| 77 } |
| 78 // Reset noise_var_ for the next frame. |
| 79 noise_var_ = 0; |
| 80 #if DISPLAY |
| 81 printf("noise_var_accum_ = %.1f, noise_var_ = %d.\n", noise_var_accum_, |
| 82 noise_var_); |
| 83 #endif |
| 84 } |
| 85 |
| 86 uint8_t NoiseEstimation::GetNoiseLevel() { |
| 87 int noise_thr = cpu_type_ ? kNoiseThreshold : kNoiseThresholdNeon; |
| 88 UpdateNoiseLevel(); |
| 89 if (noise_var_accum_ > noise_thr) { |
| 90 return 1; |
| 91 } |
| 92 return 0; |
| 93 } |
| 94 |
| 95 } // namespace webrtc |
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