1 /* Copyright (c) 2013 The Chromium OS Authors. All rights reserved. 2 * Use of this source code is governed by a BSD-style license that can be 3 * found in the LICENSE file. 4 */ 5 6 #ifndef EQ2_H_ 7 #define EQ2_H_ 8 9 #ifdef __cplusplus 10 extern "C" { 11 #endif 12 13 /* "eq2" is a two channel version of the "eq" filter. It processes two channels 14 * of data at once to increase performance. */ 15 16 #include "biquad.h" 17 18 /* Maximum number of biquad filters an EQ2 can have per channel */ 19 #define MAX_BIQUADS_PER_EQ2 10 20 21 struct eq2; 22 23 /* Create an EQ2. */ 24 struct eq2 *eq2_new(); 25 26 /* Free an EQ2. */ 27 void eq2_free(struct eq2 *eq2); 28 29 /* Append a biquad filter to an EQ2. An EQ2 can have at most MAX_BIQUADS_PER_EQ2 30 * biquad filters per channel. 31 * Args: 32 * eq2 - The EQ2 we want to use. 33 * channel - 0 or 1. The channel we want to append the filter to. 34 * type - The type of the biquad filter we want to append. 35 * frequency - The value should be in the range [0, 1]. It is relative to 36 * half of the sampling rate. 37 * Q, gain - The meaning depends on the type of the filter. See Web Audio 38 * API for details. 39 * Returns: 40 * 0 if success. -1 if the eq has no room for more biquads. 41 */ 42 int eq2_append_biquad(struct eq2 *eq2, int channel, 43 enum biquad_type type, float freq, float Q, float gain); 44 45 /* Append a biquad filter to an EQ2. An EQ2 can have at most MAX_BIQUADS_PER_EQ2 46 * biquad filters. This is similar to eq2_append_biquad(), but it specifies the 47 * biquad coefficients directly. 48 * Args: 49 * eq2 - The EQ2 we want to use. 50 * channel - 0 or 1. The channel we want to append the filter to. 51 * biquad - The parameters for the biquad filter. 52 * Returns: 53 * 0 if success. -1 if the eq has no room for more biquads. 54 */ 55 int eq2_append_biquad_direct(struct eq2 *eq2, int channel, 56 const struct biquad *biquad); 57 58 /* Process a buffer of audio data through the EQ2. 59 * Args: 60 * eq2 - The EQ2 we want to use. 61 * data0 - The array of channel 0 audio samples. 62 * data1 - The array of channel 1 audio samples. 63 * count - The number of elements in each of the data array to process. 64 */ 65 void eq2_process(struct eq2 *eq2, float *data0, float *data1, int count); 66 67 #ifdef __cplusplus 68 } /* extern "C" */ 69 #endif 70 71 #endif /* EQ2_H_ */ 72
