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58 lines
2.0 KiB
58 lines
2.0 KiB
/* Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef CRAS_VOLUME_CURVE_H_
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#define CRAS_VOLUME_CURVE_H_
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#define MAX_VOLUME 100
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#define NUM_VOLUME_STEPS (MAX_VOLUME + 1) /* 0-100 inclusive. */
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/* Holds the function that converts from a volume index to a dBFS value. */
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struct cras_volume_curve {
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/* Function to convert from index to dBFS value.
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* Args:
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* curve - A curve from cras_volume_curve_create_* functions.
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* volume - The volume level from 0 to 100.
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* Returns:
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* The volume to apply in dB * 100. This value will normally be
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* negative and is means dB down from full scale.
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*/
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long (*get_dBFS)(const struct cras_volume_curve *curve, size_t volume);
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};
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/* Creates a system-default volume curve. The default curve maps one volume step
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* to 1 dB down.
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* Returns null on error, or the new volume curve on success.
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*/
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struct cras_volume_curve *cras_volume_curve_create_default();
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/* Creates a volume curve with a specified max volume and step.
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* Args:
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* max_volume - Maximum volume allowed in dBFS.
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* volume_step - Number of dB to change for one volume tick.
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*/
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struct cras_volume_curve *
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cras_volume_curve_create_simple_step(long max_volume, long volume_step);
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/* Creates a volume curve with each step's dB value called out.
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* Args:
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* dB_values - Each element specifies what the volume should be set to (in
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* dB) for the volume at that index.
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* Returns:
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* A volume curve pointer that should be passed to
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* cras_volume_curve_destroy() when it is no longer needed. If there is an
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* error NULL will be returned.
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*/
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struct cras_volume_curve *
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cras_volume_curve_create_explicit(long dB_values[101]);
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/* Destroys a curve created with cras_volume_curve_create_*.
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* Args:
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* curve - The curve to destroy.
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*/
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void cras_volume_curve_destroy(struct cras_volume_curve *curve);
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#endif /* CRAS_VOLUME_CURVE_H_ */
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