Hearing Aid Audio HAL

cc_defaults {

    name: "audio_hearing_aid_hw_defaults",

    defaults: ["fluoride_defaults"],

    include_dirs: [

        "packages/modules/Bluetooth/system",

        "packages/modules/Bluetooth/system/include",

        "packages/modules/Bluetooth/system/audio_hearing_aid_hw/include",

    ]

}

// Audio A2DP shared library for target

// ========================================================

cc_library {

    name: "audio.hearing_aid.default",

    defaults: ["audio_hearing_aid_hw_defaults"],

    relative_install_path: "hw",

    srcs: [

        "src/audio_hearing_aid_hw.cc",

        "src/audio_hearing_aid_hw_utils.cc",

    ],

    shared_libs: [

        "liblog",

    ],

    static_libs: ["libosi"],

}

cc_library_static {

    name: "libaudio-hearing-aid-hw-utils",

    defaults: ["audio_hearing_aid_hw_defaults"],

    srcs: [

        "src/audio_hearing_aid_hw_utils.cc",

    ],

}

// Audio A2DP library unit tests for target and host

// ========================================================

cc_test {

    name: "net_test_audio_hearing_aid_hw",

    test_suites: ["device-tests"],

    defaults: ["audio_hearing_aid_hw_defaults"],

    srcs: [

        "test/audio_hearing_aid_hw_test.cc",

    ],

    shared_libs: [

        "liblog",

    ],

    static_libs: [

        "audio.hearing_aid.default",

        "libosi",

    ],

}

/******************************************************************************

 *

 *  Copyright 2016 The Android Open Source Project

 *

 *  Licensed under the Apache License, Version 2.0 (the "License");

 *  you may not use this file except in compliance with the License.

 *  You may obtain a copy of the License at:

 *

 *  http://www.apache.org/licenses/LICENSE-2.0

 *

 *  Unless required by applicable law or agreed to in writing, software

 *  distributed under the License is distributed on an "AS IS" BASIS,

 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 *  See the License for the specific language governing permissions and

 *  limitations under the License.

 *

 ******************************************************************************/

/*****************************************************************************

 *

 *  Filename:      audio_hearing_aid_hw.h

 *

 *  Description:

 *

 *****************************************************************************/

#ifndef AUDIO_HEARING_AID_HW_H

#define AUDIO_HEARING_AID_HW_H

#include <stdint.h>

#include <hardware/bt_av.h>

/*****************************************************************************

 *  Constants & Macros

 *****************************************************************************/

#define HEARING_AID_AUDIO_HARDWARE_INTERFACE "audio.hearing_aid"

#define HEARING_AID_CTRL_PATH "/data/misc/bluedroid/.hearing_aid_ctrl"

#define HEARING_AID_DATA_PATH "/data/misc/bluedroid/.hearing_aid_data"

// AUDIO_STREAM_OUTPUT_BUFFER_SZ controls the size of the audio socket buffer.

// If one assumes the write buffer is always full during normal BT playback,

// then increasing this value increases our playback latency.

//

// FIXME: The BT HAL should consume data at a constant rate.

// AudioFlinger assumes that the HAL draws data at a constant rate, which is

// true for most audio devices; however, the BT engine reads data at a variable

// rate (over the short term), which confuses both AudioFlinger as well as

// applications which deliver data at a (generally) fixed rate.

//

// 20 * 512 is not sufficient to smooth the variability for some BT devices,

// resulting in mixer sleep and throttling. We increase this to 28 * 512 to help

// reduce the effect of variable data consumption.

#define AUDIO_STREAM_OUTPUT_BUFFER_SZ (28 * 512)

#define AUDIO_STREAM_CONTROL_OUTPUT_BUFFER_SZ 256

// AUDIO_STREAM_OUTPUT_BUFFER_PERIODS controls how the socket buffer is divided

// for AudioFlinger data delivery. The AudioFlinger mixer delivers data in

// chunks of AUDIO_STREAM_OUTPUT_BUFFER_SZ / AUDIO_STREAM_OUTPUT_BUFFER_PERIODS.

// If the number of periods is 2, the socket buffer represents "double

// buffering" of the AudioFlinger mixer buffer.

//

// In general, AUDIO_STREAM_OUTPUT_BUFFER_PERIODS * 16 * 4 should be a divisor

// of AUDIO_STREAM_OUTPUT_BUFFER_SZ.

//

// These values should be chosen such that

//

// AUDIO_STREAM_BUFFER_SIZE * 1000 / (AUDIO_STREAM_OUTPUT_BUFFER_PERIODS

//         * AUDIO_STREAM_DEFAULT_RATE * 4) > 20 (ms)

//

// to avoid introducing the FastMixer in AudioFlinger. Using the FastMixer

// results in unnecessary latency and CPU overhead for Bluetooth.

#define AUDIO_STREAM_OUTPUT_BUFFER_PERIODS 2

#define AUDIO_SKT_DISCONNECTED (-1)

typedef enum {

  HEARING_AID_CTRL_CMD_NONE,

  HEARING_AID_CTRL_CMD_CHECK_READY,

  HEARING_AID_CTRL_CMD_START,

  HEARING_AID_CTRL_CMD_STOP,

  HEARING_AID_CTRL_CMD_SUSPEND,

  HEARING_AID_CTRL_GET_INPUT_AUDIO_CONFIG,

  HEARING_AID_CTRL_GET_OUTPUT_AUDIO_CONFIG,

  HEARING_AID_CTRL_SET_OUTPUT_AUDIO_CONFIG,

  HEARING_AID_CTRL_CMD_OFFLOAD_START,

} tHEARING_AID_CTRL_CMD;

typedef enum {

  HEARING_AID_CTRL_ACK_SUCCESS,

  HEARING_AID_CTRL_ACK_FAILURE,

  HEARING_AID_CTRL_ACK_INCALL_FAILURE, /* Failure when in Call*/

  HEARING_AID_CTRL_ACK_UNSUPPORTED

} tHEARING_AID_CTRL_ACK;

typedef uint32_t tHA_SAMPLE_RATE;

typedef uint8_t tHA_CHANNEL_COUNT;

/*****************************************************************************

 *  Type definitions for callback functions

 *****************************************************************************/

/*****************************************************************************

 *  Type definitions and return values

 *****************************************************************************/

/*****************************************************************************

 *  Extern variables and functions

 *****************************************************************************/

/*****************************************************************************

 *  Functions

 *****************************************************************************/

// Computes the Audio Hearing Aid HAL output buffer size.

// |codec_sample_rate| is the sample rate of the output stream.

// |codec_bits_per_sample| is the number of bits per sample of the output

// stream.

// |codec_channel_mode| is the channel mode of the output stream.

//

// The buffer size is computed by using the following formula:

//

// AUDIO_STREAM_OUTPUT_BUFFER_SIZE =

//    (TIME_PERIOD_MS * AUDIO_STREAM_OUTPUT_BUFFER_PERIODS *

//     SAMPLE_RATE_HZ * NUMBER_OF_CHANNELS * (BITS_PER_SAMPLE / 8)) / 1000

//

// AUDIO_STREAM_OUTPUT_BUFFER_PERIODS controls how the socket buffer is

// divided for AudioFlinger data delivery. The AudioFlinger mixer delivers

// data in chunks of

// (AUDIO_STREAM_OUTPUT_BUFFER_SIZE / AUDIO_STREAM_OUTPUT_BUFFER_PERIODS) .

// If the number of periods is 2, the socket buffer represents "double

// buffering" of the AudioFlinger mixer buffer.

//

// Furthermore, the AudioFlinger expects the buffer size to be a multiple

// of 16 frames.

//

// NOTE: Currently, the computation uses the conservative 20ms time period.

//

// Returns the computed buffer size. If any of the input parameters is

// invalid, the return value is the default |AUDIO_STREAM_OUTPUT_BUFFER_SZ|.

extern size_t audio_ha_hw_stream_compute_buffer_size(

    btav_a2dp_codec_sample_rate_t codec_sample_rate,

    btav_a2dp_codec_bits_per_sample_t codec_bits_per_sample,

    btav_a2dp_codec_channel_mode_t codec_channel_mode);

// Returns a string representation of |event|.

extern const char* audio_ha_hw_dump_ctrl_event(tHEARING_AID_CTRL_CMD event);

#endif /* AUDIO_HEARING_AID_HW_H */