bluetooth/audio/2.0/IBluetoothAudioPort.hal

/*
 * Copyright 2018 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.
 */

package android.hardware.bluetooth.audio@2.0;

import android.hardware.audio.common@5.0::SourceMetadata;

/**
 * HAL interface from the Audio HAL to the Bluetooth stack
 *
 * The Audio HAL calls methods in this interface to start, suspend, and stop
 * an audio stream. These calls return immediately and the results, if any,
 * are sent over the IBluetoothAudioProvider interface.
 *
 * Moreover, the Audio HAL can also get the presentation position of the stream
 * and provide stream metadata.
 *
 * Note: For HIDL APIs with a "generates" statement, the callback parameter used
 * for return value must be invoked synchronously before the API call returns.
 */
interface IBluetoothAudioPort {
    /**
     * This indicates that the caller of this method has opened the data path
     * and wants to start an audio stream. The caller must wait for a
     * IBluetoothAudioProvider.streamStarted(Status) call.
     */
    startStream();

    /**
     * This indicates that the caller of this method wants to suspend the audio
     * stream. The caller must wait for the Bluetooth process to call
     * IBluetoothAudioProvider.streamSuspended(Status). The caller still keeps
     * the data path open.
     */
    suspendStream();

    /**
     * This indicates that the caller of this method wants to stop the audio
     * stream. The data path will be closed after this call. There is no
     * callback from the IBluetoothAudioProvider interface even though the
     * teardown is asynchronous.
     */
    stopStream();

    /**
     * Get the audio presentation position.
     *
     * @return status the command status
     * @return remoteDeviceAudioDelayNanos the audio delay from when the remote
     *    device (e.g. headset) receives audio data to when the device plays the
     *    sound. If the delay is unknown, the value is set to zero.
     * @return transmittedOctets the number of audio data octets that were sent
     *    to a remote device. This excludes octets that have been written to the
     *    data path but have not been sent to the remote device. The count is
     *    not reset until stopStream() is called. If the software data path is
     *    unused (e.g. A2DP Hardware Offload), the value is set to 0.
     * @return transmittedOctetsTimeStamp the value of CLOCK_MONOTONIC
     *    corresponding to transmittedOctets. If the software data path is
     *    unused (e.g., for A2DP Hardware Offload), the value is set to zero.
     */
    getPresentationPosition() generates (Status status,
        uint64_t remoteDeviceAudioDelayNanos, uint64_t transmittedOctets,
        TimeSpec transmittedOctetsTimeStamp);

    /**
     * Called when the metadata of the stream's source has been changed.
     *
     * @param sourceMetadata Description of the audio that is played by the
     *    clients.
     */
    updateMetadata(SourceMetadata sourceMetadata);
};