/******************************************************************************
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*
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* Copyright 2009-2012 Broadcom Corporation
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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******************************************************************************/
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/*****************************************************************************
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*
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* Filename: audio_a2dp_hw.h
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*
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* Description:
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*
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*****************************************************************************/
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#ifndef AUDIO_A2DP_HW_H
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#define AUDIO_A2DP_HW_H
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#include <stdint.h>
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#include <hardware/bt_av.h>
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/*****************************************************************************
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* Constants & Macros
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*****************************************************************************/
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#define A2DP_AUDIO_HARDWARE_INTERFACE "audio.a2dp"
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#define A2DP_CTRL_PATH "/data/misc/bluedroid/.a2dp_ctrl"
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#define A2DP_DATA_PATH "/data/misc/bluedroid/.a2dp_data"
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// AUDIO_STREAM_OUTPUT_BUFFER_SZ controls the size of the audio socket buffer.
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// If one assumes the write buffer is always full during normal BT playback,
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// then increasing this value increases our playback latency.
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//
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// FIXME: The BT HAL should consume data at a constant rate.
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// AudioFlinger assumes that the HAL draws data at a constant rate, which is
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// true for most audio devices; however, the BT engine reads data at a variable
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// rate (over the short term), which confuses both AudioFlinger as well as
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// applications which deliver data at a (generally) fixed rate.
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//
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// 20 * 512 is not sufficient to smooth the variability for some BT devices,
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// resulting in mixer sleep and throttling. We increase this to 28 * 512 to help
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// reduce the effect of variable data consumption.
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#define AUDIO_STREAM_OUTPUT_BUFFER_SZ (28 * 512)
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#define AUDIO_STREAM_CONTROL_OUTPUT_BUFFER_SZ 256
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// AUDIO_STREAM_OUTPUT_BUFFER_PERIODS controls how the socket buffer is divided
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// for AudioFlinger data delivery. The AudioFlinger mixer delivers data in
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// chunks of AUDIO_STREAM_OUTPUT_BUFFER_SZ / AUDIO_STREAM_OUTPUT_BUFFER_PERIODS.
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// If the number of periods is 2, the socket buffer represents "double
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// buffering" of the AudioFlinger mixer buffer.
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//
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// In general, AUDIO_STREAM_OUTPUT_BUFFER_PERIODS * 16 * 4 should be a divisor
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// of AUDIO_STREAM_OUTPUT_BUFFER_SZ.
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//
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// These values should be chosen such that
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//
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// AUDIO_STREAM_BUFFER_SIZE * 1000 / (AUDIO_STREAM_OUTPUT_BUFFER_PERIODS
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// * AUDIO_STREAM_DEFAULT_RATE * 4) > 20 (ms)
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//
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// to avoid introducing the FastMixer in AudioFlinger. Using the FastMixer
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// results in unnecessary latency and CPU overhead for Bluetooth.
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#define AUDIO_STREAM_OUTPUT_BUFFER_PERIODS 2
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#define AUDIO_SKT_DISCONNECTED (-1)
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typedef enum {
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A2DP_CTRL_CMD_NONE,
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A2DP_CTRL_CMD_CHECK_READY,
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A2DP_CTRL_CMD_START,
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A2DP_CTRL_CMD_STOP,
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A2DP_CTRL_CMD_SUSPEND,
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A2DP_CTRL_GET_INPUT_AUDIO_CONFIG,
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A2DP_CTRL_GET_OUTPUT_AUDIO_CONFIG,
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A2DP_CTRL_SET_OUTPUT_AUDIO_CONFIG,
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A2DP_CTRL_CMD_OFFLOAD_START,
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A2DP_CTRL_GET_PRESENTATION_POSITION,
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} tA2DP_CTRL_CMD;
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typedef enum {
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A2DP_CTRL_ACK_SUCCESS,
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A2DP_CTRL_ACK_FAILURE,
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A2DP_CTRL_ACK_INCALL_FAILURE, /* Failure when in Call*/
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A2DP_CTRL_ACK_UNSUPPORTED,
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A2DP_CTRL_ACK_PENDING,
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A2DP_CTRL_ACK_DISCONNECT_IN_PROGRESS,
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} tA2DP_CTRL_ACK;
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typedef uint32_t tA2DP_SAMPLE_RATE;
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typedef uint8_t tA2DP_CHANNEL_COUNT;
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typedef uint8_t tA2DP_BITS_PER_SAMPLE;
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/*****************************************************************************
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* Type definitions for callback functions
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*****************************************************************************/
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/*****************************************************************************
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* Type definitions and return values
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*****************************************************************************/
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/*****************************************************************************
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* Extern variables and functions
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*****************************************************************************/
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/*****************************************************************************
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* Functions
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*****************************************************************************/
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// Computes the Audio A2DP HAL output buffer size.
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// |codec_sample_rate| is the sample rate of the output stream.
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// |codec_bits_per_sample| is the number of bits per sample of the output
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// stream.
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// |codec_channel_mode| is the channel mode of the output stream.
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//
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// The buffer size is computed by using the following formula:
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//
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// AUDIO_STREAM_OUTPUT_BUFFER_SIZE =
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// (TIME_PERIOD_MS * AUDIO_STREAM_OUTPUT_BUFFER_PERIODS *
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// SAMPLE_RATE_HZ * NUMBER_OF_CHANNELS * (BITS_PER_SAMPLE / 8)) / 1000
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//
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// AUDIO_STREAM_OUTPUT_BUFFER_PERIODS controls how the socket buffer is
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// divided for AudioFlinger data delivery. The AudioFlinger mixer delivers
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// data in chunks of
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// (AUDIO_STREAM_OUTPUT_BUFFER_SIZE / AUDIO_STREAM_OUTPUT_BUFFER_PERIODS) .
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// If the number of periods is 2, the socket buffer represents "double
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// buffering" of the AudioFlinger mixer buffer.
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//
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// Furthermore, the AudioFlinger expects the buffer size to be a multiple
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// of 16 frames.
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//
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// NOTE: Currently, the computation uses the conservative 20ms time period.
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//
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// Returns the computed buffer size. If any of the input parameters is
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// invalid, the return value is the default |AUDIO_STREAM_OUTPUT_BUFFER_SZ|.
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size_t audio_a2dp_hw_stream_compute_buffer_size(
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btav_a2dp_codec_sample_rate_t codec_sample_rate,
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btav_a2dp_codec_bits_per_sample_t codec_bits_per_sample,
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btav_a2dp_codec_channel_mode_t codec_channel_mode);
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// Returns whether the delay reporting property is set.
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bool delay_reporting_enabled();
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// Returns a string representation of |event|.
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const char* audio_a2dp_hw_dump_ctrl_event(tA2DP_CTRL_CMD event);
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#endif /* A2DP_AUDIO_HW_H */
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