1 /****************************************************************************** 2 * 3 * Copyright 2016 The Android Open Source Project 4 * 5 * Licensed under the Apache License, Version 2.0 (the "License"); 6 * you may not use this file except in compliance with the License. 7 * You may obtain a copy of the License at: 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 * 17 ******************************************************************************/ 18 19 /***************************************************************************** 20 * 21 * Filename: audio_hearing_aid_hw.h 22 * 23 * Description: 24 * 25 *****************************************************************************/ 26 27 #ifndef AUDIO_HEARING_AID_HW_H 28 #define AUDIO_HEARING_AID_HW_H 29 30 #include <hardware/bt_av.h> 31 #include <stdint.h> 32 33 /***************************************************************************** 34 * Constants & Macros 35 *****************************************************************************/ 36 37 #define HEARING_AID_AUDIO_HARDWARE_INTERFACE "audio.hearing_aid" 38 #define HEARING_AID_CTRL_PATH "/data/misc/bluedroid/.hearing_aid_ctrl" 39 #define HEARING_AID_DATA_PATH "/data/misc/bluedroid/.hearing_aid_data" 40 41 // AUDIO_STREAM_OUTPUT_BUFFER_SZ controls the size of the audio socket buffer. 42 // If one assumes the write buffer is always full during normal BT playback, 43 // then increasing this value increases our playback latency. 44 // 45 // FIXME: The BT HAL should consume data at a constant rate. 46 // AudioFlinger assumes that the HAL draws data at a constant rate, which is 47 // true for most audio devices; however, the BT engine reads data at a variable 48 // rate (over the short term), which confuses both AudioFlinger as well as 49 // applications which deliver data at a (generally) fixed rate. 50 // 51 // 20 * 512 is not sufficient to smooth the variability for some BT devices, 52 // resulting in mixer sleep and throttling. We increase this to 28 * 512 to help 53 // reduce the effect of variable data consumption. 54 #define AUDIO_STREAM_OUTPUT_BUFFER_SZ (28 * 512) 55 #define AUDIO_STREAM_CONTROL_OUTPUT_BUFFER_SZ 256 56 57 // AUDIO_STREAM_OUTPUT_BUFFER_PERIODS controls how the socket buffer is divided 58 // for AudioFlinger data delivery. The AudioFlinger mixer delivers data in 59 // chunks of AUDIO_STREAM_OUTPUT_BUFFER_SZ / AUDIO_STREAM_OUTPUT_BUFFER_PERIODS. 60 // If the number of periods is 2, the socket buffer represents "double 61 // buffering" of the AudioFlinger mixer buffer. 62 // 63 // In general, AUDIO_STREAM_OUTPUT_BUFFER_PERIODS * 16 * 4 should be a divisor 64 // of AUDIO_STREAM_OUTPUT_BUFFER_SZ. 65 // 66 // These values should be chosen such that 67 // 68 // AUDIO_STREAM_BUFFER_SIZE * 1000 / (AUDIO_STREAM_OUTPUT_BUFFER_PERIODS 69 // * AUDIO_STREAM_DEFAULT_RATE * 4) > 20 (ms) 70 // 71 // to avoid introducing the FastMixer in AudioFlinger. Using the FastMixer 72 // results in unnecessary latency and CPU overhead for Bluetooth. 73 #define AUDIO_STREAM_OUTPUT_BUFFER_PERIODS 2 74 75 #define AUDIO_SKT_DISCONNECTED (-1) 76 77 typedef enum { 78 HEARING_AID_CTRL_CMD_NONE, 79 HEARING_AID_CTRL_CMD_CHECK_READY, 80 HEARING_AID_CTRL_CMD_START, 81 HEARING_AID_CTRL_CMD_STOP, 82 HEARING_AID_CTRL_CMD_SUSPEND, 83 HEARING_AID_CTRL_GET_INPUT_AUDIO_CONFIG, 84 HEARING_AID_CTRL_GET_OUTPUT_AUDIO_CONFIG, 85 HEARING_AID_CTRL_SET_OUTPUT_AUDIO_CONFIG, 86 HEARING_AID_CTRL_CMD_OFFLOAD_START, 87 } tHEARING_AID_CTRL_CMD; 88 89 typedef enum { 90 HEARING_AID_CTRL_ACK_SUCCESS, 91 HEARING_AID_CTRL_ACK_FAILURE, 92 HEARING_AID_CTRL_ACK_INCALL_FAILURE, /* Failure when in Call*/ 93 HEARING_AID_CTRL_ACK_UNSUPPORTED 94 } tHEARING_AID_CTRL_ACK; 95 96 typedef uint32_t tHA_SAMPLE_RATE; 97 typedef uint8_t tHA_CHANNEL_COUNT; 98 99 /***************************************************************************** 100 * Type definitions for callback functions 101 *****************************************************************************/ 102 103 /***************************************************************************** 104 * Type definitions and return values 105 *****************************************************************************/ 106 107 /***************************************************************************** 108 * Extern variables and functions 109 *****************************************************************************/ 110 111 /***************************************************************************** 112 * Functions 113 *****************************************************************************/ 114 115 // Computes the Audio Hearing Aid HAL output buffer size. 116 // |codec_sample_rate| is the sample rate of the output stream. 117 // |codec_bits_per_sample| is the number of bits per sample of the output 118 // stream. 119 // |codec_channel_mode| is the channel mode of the output stream. 120 // 121 // The buffer size is computed by using the following formula: 122 // 123 // AUDIO_STREAM_OUTPUT_BUFFER_SIZE = 124 // (TIME_PERIOD_MS * AUDIO_STREAM_OUTPUT_BUFFER_PERIODS * 125 // SAMPLE_RATE_HZ * NUMBER_OF_CHANNELS * (BITS_PER_SAMPLE / 8)) / 1000 126 // 127 // AUDIO_STREAM_OUTPUT_BUFFER_PERIODS controls how the socket buffer is 128 // divided for AudioFlinger data delivery. The AudioFlinger mixer delivers 129 // data in chunks of 130 // (AUDIO_STREAM_OUTPUT_BUFFER_SIZE / AUDIO_STREAM_OUTPUT_BUFFER_PERIODS) . 131 // If the number of periods is 2, the socket buffer represents "double 132 // buffering" of the AudioFlinger mixer buffer. 133 // 134 // Furthermore, the AudioFlinger expects the buffer size to be a multiple 135 // of 16 frames. 136 // 137 // NOTE: Currently, the computation uses the conservative 20ms time period. 138 // 139 // Returns the computed buffer size. If any of the input parameters is 140 // invalid, the return value is the default |AUDIO_STREAM_OUTPUT_BUFFER_SZ|. 141 size_t audio_ha_hw_stream_compute_buffer_size( 142 btav_a2dp_codec_sample_rate_t codec_sample_rate, 143 btav_a2dp_codec_bits_per_sample_t codec_bits_per_sample, 144 btav_a2dp_codec_channel_mode_t codec_channel_mode); 145 146 #endif /* AUDIO_HEARING_AID_HW_H */ 147