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151 lines
6.0 KiB
151 lines
6.0 KiB
/****************************************************************************** |
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* |
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* Copyright (C) 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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} 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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} 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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extern 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 a string representation of |event|. |
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extern 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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