gain_map_internal.h (2467B)
1 /* 2 * Copyright (c) 2013 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 #ifndef MODULES_AUDIO_PROCESSING_AGC2_GAIN_MAP_INTERNAL_H_ 12 #define MODULES_AUDIO_PROCESSING_AGC2_GAIN_MAP_INTERNAL_H_ 13 14 namespace webrtc { 15 16 static constexpr int kGainMapSize = 256; 17 // Maps input volumes, which are values in the [0, 255] range, to gains in dB. 18 // The values below are generated with numpy as follows: 19 // SI = 2 # Initial slope. 20 // SF = 0.25 # Final slope. 21 // D = 8/256 # Quantization factor. 22 // x = np.linspace(0, 255, 256) # Input volumes. 23 // y = (SF * x + (SI - SF) * (1 - np.exp(-D*x)) / D - 56).round() 24 static const int kGainMap[kGainMapSize] = { 25 -56, -54, -52, -50, -48, -47, -45, -43, -42, -40, -38, -37, -35, -34, -33, 26 -31, -30, -29, -27, -26, -25, -24, -23, -22, -20, -19, -18, -17, -16, -15, 27 -14, -14, -13, -12, -11, -10, -9, -8, -8, -7, -6, -5, -5, -4, -3, 28 -2, -2, -1, 0, 0, 1, 1, 2, 3, 3, 4, 4, 5, 5, 6, 29 6, 7, 7, 8, 8, 9, 9, 10, 10, 11, 11, 12, 12, 13, 13, 30 13, 14, 14, 15, 15, 15, 16, 16, 17, 17, 17, 18, 18, 18, 19, 31 19, 19, 20, 20, 21, 21, 21, 22, 22, 22, 23, 23, 23, 24, 24, 32 24, 24, 25, 25, 25, 26, 26, 26, 27, 27, 27, 28, 28, 28, 28, 33 29, 29, 29, 30, 30, 30, 30, 31, 31, 31, 32, 32, 32, 32, 33, 34 33, 33, 33, 34, 34, 34, 35, 35, 35, 35, 36, 36, 36, 36, 37, 35 37, 37, 38, 38, 38, 38, 39, 39, 39, 39, 40, 40, 40, 40, 41, 36 41, 41, 41, 42, 42, 42, 42, 43, 43, 43, 44, 44, 44, 44, 45, 37 45, 45, 45, 46, 46, 46, 46, 47, 47, 47, 47, 48, 48, 48, 48, 38 49, 49, 49, 49, 50, 50, 50, 50, 51, 51, 51, 51, 52, 52, 52, 39 52, 53, 53, 53, 53, 54, 54, 54, 54, 55, 55, 55, 55, 56, 56, 40 56, 56, 57, 57, 57, 57, 58, 58, 58, 58, 59, 59, 59, 59, 60, 41 60, 60, 60, 61, 61, 61, 61, 62, 62, 62, 62, 63, 63, 63, 63, 42 64}; 43 44 } // namespace webrtc 45 46 #endif // MODULES_AUDIO_PROCESSING_AGC2_GAIN_MAP_INTERNAL_H_