| /****************************************************************************** |
| * |
| * Copyright 2009-2012 Broadcom Corporation |
| * |
| * 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_a2dp_hw.h |
| * |
| * Description: |
| * |
| *****************************************************************************/ |
| |
| #ifndef AUDIO_A2DP_HW_H |
| #define AUDIO_A2DP_HW_H |
| |
| #include <stdint.h> |
| |
| #include <hardware/bt_av.h> |
| |
| /***************************************************************************** |
| * Constants & Macros |
| *****************************************************************************/ |
| |
| #define A2DP_AUDIO_HARDWARE_INTERFACE "audio.a2dp" |
| #define A2DP_CTRL_PATH "/data/misc/bluedroid/.a2dp_ctrl" |
| #define A2DP_DATA_PATH "/data/misc/bluedroid/.a2dp_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 { |
| A2DP_CTRL_CMD_NONE, |
| A2DP_CTRL_CMD_CHECK_READY, |
| A2DP_CTRL_CMD_START, |
| A2DP_CTRL_CMD_STOP, |
| A2DP_CTRL_CMD_SUSPEND, |
| A2DP_CTRL_GET_INPUT_AUDIO_CONFIG, |
| A2DP_CTRL_GET_OUTPUT_AUDIO_CONFIG, |
| A2DP_CTRL_SET_OUTPUT_AUDIO_CONFIG, |
| A2DP_CTRL_CMD_OFFLOAD_START, |
| A2DP_CTRL_GET_PRESENTATION_POSITION, |
| } tA2DP_CTRL_CMD; |
| |
| typedef enum { |
| A2DP_CTRL_ACK_SUCCESS, |
| A2DP_CTRL_ACK_FAILURE, |
| A2DP_CTRL_ACK_INCALL_FAILURE, /* Failure when in Call*/ |
| A2DP_CTRL_ACK_UNSUPPORTED, |
| A2DP_CTRL_ACK_PENDING, |
| A2DP_CTRL_ACK_DISCONNECT_IN_PROGRESS, |
| } tA2DP_CTRL_ACK; |
| |
| typedef uint32_t tA2DP_SAMPLE_RATE; |
| typedef uint8_t tA2DP_CHANNEL_COUNT; |
| typedef uint8_t tA2DP_BITS_PER_SAMPLE; |
| |
| /***************************************************************************** |
| * Type definitions for callback functions |
| *****************************************************************************/ |
| |
| /***************************************************************************** |
| * Type definitions and return values |
| *****************************************************************************/ |
| |
| /***************************************************************************** |
| * Extern variables and functions |
| *****************************************************************************/ |
| |
| /***************************************************************************** |
| * Functions |
| *****************************************************************************/ |
| |
| // Computes the Audio A2DP 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|. |
| size_t audio_a2dp_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 whether the delay reporting property is set. |
| bool delay_reporting_enabled(); |
| |
| // Returns a string representation of |event|. |
| const char* audio_a2dp_hw_dump_ctrl_event(tA2DP_CTRL_CMD event); |
| |
| #endif /* A2DP_AUDIO_HW_H */ |