audio/hal/dsp/eq2.h

/* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef EQ2_H_
#define EQ2_H_

#ifdef __cplusplus
extern "C" {
#endif

/* "eq2" is a two channel version of the "eq" filter. It processes two channels
 * of data at once to increase performance. */

#include "biquad.h"

/* Maximum number of biquad filters an EQ2 can have per channel */
#define MAX_BIQUADS_PER_EQ2 10

struct eq2;

/* Create an EQ2. */
struct eq2 *eq2_new();

/* Free an EQ2. */
void eq2_free(struct eq2 *eq2);

/* Append a biquad filter to an EQ2. An EQ2 can have at most MAX_BIQUADS_PER_EQ2
 * biquad filters per channel.
 * Args:
 *    eq2 - The EQ2 we want to use.
 *    channel - 0 or 1. The channel we want to append the filter to.
 *    type - The type of the biquad filter we want to append.
 *    frequency - The value should be in the range [0, 1]. It is relative to
 *        half of the sampling rate.
 *    Q, gain - The meaning depends on the type of the filter. See Web Audio
 *        API for details.
 * Returns:
 *    0 if success. -1 if the eq has no room for more biquads.
 */
int eq2_append_biquad(struct eq2 *eq2, int channel,
		      enum biquad_type type, float freq, float Q, float gain);

/* Append a biquad filter to an EQ2. An EQ2 can have at most MAX_BIQUADS_PER_EQ2
 * biquad filters. This is similar to eq2_append_biquad(), but it specifies the
 * biquad coefficients directly.
 * Args:
 *    eq2 - The EQ2 we want to use.
 *    channel - 0 or 1. The channel we want to append the filter to.
 *    biquad - The parameters for the biquad filter.
 * Returns:
 *    0 if success. -1 if the eq has no room for more biquads.
 */
int eq2_append_biquad_direct(struct eq2 *eq2, int channel,
			     const struct biquad *biquad);

/* Process a buffer of audio data through the EQ2.
 * Args:
 *    eq2 - The EQ2 we want to use.
 *    data0 - The array of channel 0 audio samples.
 *    data1 - The array of channel 1 audio samples.
 *    count - The number of elements in each of the data array to process.
 */
void eq2_process(struct eq2 *eq2, float *data0, float *data1, int count);

#ifdef __cplusplus
} /* extern "C" */
#endif

#endif /* EQ2_H_ */