automotive/audiocontrol/1.0/IAudioControlCallback.hal

/*
 * Copyright (C) 2017 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.automotive.audiocontrol@1.0;


/**
 * Implemented on client (framework) side to receive asynchronous updates from the car.
 */
interface IAudioControlCallback {

    /**
     * When the HAL makes this call, any apps currently playing must be asked to
     * temporarily suspend playback (via an AudioManager::AUDIOFOCUS_LOSS_TRANSIENT event).
     *
     * This is only a suggestion. Apps may be slow to react or even ignore this message
     * entirely. Enforcement, if necessary, must be done at the AudioHAL level as the
     * samples are delivered. In most instances, this is the way a car should ask for
     * quiet if it needs it for some important situation, such as warning alarms or chimes.
     */
    oneway suggestPausePlayers();


    /**
     * When the HAL makes this case, any apps currently playing must be asked to stop
     * playing (via an AudioManager::AUDIOFOCUS_LOSS event). Once stopped, the apps must
     * not resume their playback.
     *
     * It should be noted that not all apps or sound sources honor this request, but this
     * at least gives an app the chance to do the right thing.
     * Because it premanently stops media, this call is expected to be used only rarely.
     * Perhaps in the event of an E-call, where resuming music might be undesirable assuming
     * the driver is now dealing with whatever the emergency is?
     */
    oneway suggestStopPlayers();


    /**
     * Receives calls from the HAL when Android should resume normal operations. If the previous
     * action was a requestPausePlayers, then things that were paused must be told they may
     * resume.
     */
    oneway resumePlayers();
};