Android 4.4音量键控制音量流程

原文链接：http://www.cnblogs.com/Michelangelo/p/4710068.html

1、在AudioManager.java中的handleKeyDown函数中接收音量键的按键消息

public void handleKeyDown(KeyEvent event, int stream) {
        int keyCode = event.getKeyCode();
        switch (keyCode) {
            case KeyEvent.KEYCODE_VOLUME_UP:
            case KeyEvent.KEYCODE_VOLUME_DOWN:
                /*
                 * Adjust the volume in on key down since it is more
                 * responsive to the user.
                 */
                int flags = FLAG_SHOW_UI | FLAG_VIBRATE;
                if (mUseMasterVolume) {
                    adjustMasterVolume(
                            keyCode == KeyEvent.KEYCODE_VOLUME_UP
                                    ? ADJUST_RAISE
                                    : ADJUST_LOWER,
                            flags);
                } else {
                    adjustSuggestedStreamVolume(
                            keyCode == KeyEvent.KEYCODE_VOLUME_UP
                                    ? ADJUST_RAISE
                                    : ADJUST_LOWER,
                            stream,
                            flags);
                }
                break;
            case KeyEvent.KEYCODE_VOLUME_MUTE:
                if (event.getRepeatCount() == 0) {
                    if (mUseMasterVolume) {
                        setMasterMute(!isMasterMute());
                    } else {
                        // TODO: Actually handle MUTE.
                    }
                }
                break;
        }
    }

2、根据音量键调节走else分支，进入adjustSuggestedStreamVolume函数中

    public void adjustSuggestedStreamVolume(int direction, int suggestedStreamType, int flags) {
        IAudioService service = getService();
        Log.d(TAG, "adjustSuggestedStreamVolume: Direction = " + direction
        + ", streamType = " + suggestedStreamType);
        try {
            if (mUseMasterVolume) {
                service.adjustMasterVolume(direction, flags, mContext.getOpPackageName());
            } else {
                service.adjustSuggestedStreamVolume(direction, suggestedStreamType, flags,
                        mContext.getOpPackageName());
            }
        } catch (RemoteException e) {
            Log.e(TAG, "Dead object in adjustSuggestedStreamVolume", e);
        }
    }

3、进入AudioService.java中的adjustSuggestedStreamVolume函数中

public void adjustSuggestedStreamVolume(int direction, int suggestedStreamType, int flags,
            String callingPackage) {
        if (DEBUG_VOL) Log.d(TAG, "adjustSuggestedStreamVolume() stream="+suggestedStreamType+" direction ="+direction+" flags="+flags);
        int streamType;
        Log.d(TAG, "adjustSuggestedStreamVolume() mVolumeControlStream="+mVolumeControlStream);
        if (mVolumeControlStream != -1) {
            streamType = mVolumeControlStream;
            Log.d(TAG, "adjustSuggestedStreamVolume() getMode()="+getMode());
            Log.d(TAG, "adjustSuggestedStreamVolume() AudioSystem.isStreamActive(AudioSystem.STREAM_MUSIC, 0) ="+AudioSystem.isStreamActive(AudioSystem.STREAM_MUSIC, 0));
            Log.d(TAG, "adjustSuggestedStreamVolume() AudioSystem.isStreamActive(AudioSystem.STREAM_VOICE_CALL, 0) ="+AudioSystem.isStreamActive(AudioSystem.STREAM_VOICE_CALL, 0));
        } else {
            streamType = getActiveStreamType(suggestedStreamType);
        }
Log.d(TAG, "adjustSuggestedStreamVolume() streamType2="+streamType);
        // Play sounds on STREAM_RING only and if lock screen is not on.
        if ((streamType != STREAM_REMOTE_MUSIC) &&
                (flags & AudioManager.FLAG_PLAY_SOUND) != 0 &&
                ((mStreamVolumeAlias[streamType] != AudioSystem.STREAM_RING)
                 || (mKeyguardManager != null && mKeyguardManager.isKeyguardLocked()))) {
            flags &= ~AudioManager.FLAG_PLAY_SOUND;
        }
        if (streamType == STREAM_REMOTE_MUSIC) {
            // don't play sounds for remote
            flags &= ~(AudioManager.FLAG_PLAY_SOUND|AudioManager.FLAG_FIXED_VOLUME);
            //if (DEBUG_VOL) Log.i(TAG, "Need to adjust remote volume: calling adjustRemoteVolume()");
            mMediaFocusControl.adjustRemoteVolume(AudioSystem.STREAM_MUSIC, direction, flags);
        } else {
            adjustStreamVolume(streamType, direction, flags, callingPackage);
        }
    }

4、进入adjustStreamVolume函数中

    /** @see AudioManager#adjustStreamVolume(int, int, int) */
    public void adjustStreamVolume(int streamType, int direction, int flags,
            String callingPackage) {
        if (mUseFixedVolume) {
            return;
        }
        if (DEBUG_VOL) Log.d(TAG, "adjustStreamVolume() stream="+streamType+", dir="+direction);
        ensureValidDirection(direction);
        ensureValidStreamType(streamType);
        Log.v(TAG,"adjustStreamVolume streamType1 : "+streamType);
        
        
        // use stream type alias here so that streams with same alias have the same behavior,
        // including with regard to silent mode control (e.g the use of STREAM_RING below and in
        // checkForRingerModeChange() in place of STREAM_RING or STREAM_NOTIFICATION)
        int streamTypeAlias = mStreamVolumeAlias[streamType];
        VolumeStreamState streamState = mStreamStates[streamTypeAlias];
        final int device = getDeviceForStream(streamTypeAlias);
Log.v(TAG,"adjustStreamVolume streamTypeAlias : "+streamTypeAlias+" device:"+device);
        int aliasIndex = streamState.getIndex(device);
        boolean adjustVolume = true;
        int step;
        // skip a2dp absolute volume control request when the device
        // is not an a2dp device
        if ((device & AudioSystem.DEVICE_OUT_ALL_A2DP) == 0 &&
            (flags & AudioManager.FLAG_BLUETOOTH_ABS_VOLUME) != 0) {
            return;
        }
        if (mAppOps.noteOp(STEAM_VOLUME_OPS[streamTypeAlias], Binder.getCallingUid(),
                callingPackage) != AppOpsManager.MODE_ALLOWED) {
            return;
        }
        // reset any pending volume command
        synchronized (mSafeMediaVolumeState) {
            mPendingVolumeCommand = null;
        }
        flags &= ~AudioManager.FLAG_FIXED_VOLUME;
        if ((streamTypeAlias == AudioSystem.STREAM_MUSIC) &&
               ((device & mFixedVolumeDevices) != 0)) {
            flags |= AudioManager.FLAG_FIXED_VOLUME;
            // Always toggle between max safe volume and 0 for fixed volume devices where safe
            // volume is enforced, and max and 0 for the others.
            // This is simulated by stepping by the full allowed volume range
            if (mSafeMediaVolumeState == SAFE_MEDIA_VOLUME_ACTIVE &&
                    (device & mSafeMediaVolumeDevices) != 0) {
                step = mSafeMediaVolumeIndex;
            } else {
                step = streamState.getMaxIndex();
            }
            if (aliasIndex != 0) {
                aliasIndex = step;
            }
        } else {
            // convert one UI step (+/-1) into a number of internal units on the stream alias
            step = rescaleIndex(10, streamType, streamTypeAlias);
        }
        // If either the client forces allowing ringer modes for this adjustment,
        // or the stream type is one that is affected by ringer modes
        if (((flags & AudioManager.FLAG_ALLOW_RINGER_MODES) != 0) ||
                (streamTypeAlias == getMasterStreamType())) {
            int ringerMode = getRingerMode();
            // do not vibrate if already in vibrate mode
            if (ringerMode == AudioManager.RINGER_MODE_VIBRATE) {
                flags &= ~AudioManager.FLAG_VIBRATE;
            }
            // Check if the ringer mode changes with this volume adjustment. If
            // it does, it will handle adjusting the volume, so we won't below
            adjustVolume = checkForRingerModeChange(aliasIndex, direction, step);
        }
        int oldIndex = mStreamStates[streamType].getIndex(device);
        if (adjustVolume && (direction != AudioManager.ADJUST_SAME)) {
            // Check if volume update should be send to AVRCP
            if (streamTypeAlias == AudioSystem.STREAM_MUSIC &&
                (device & AudioSystem.DEVICE_OUT_ALL_A2DP) != 0 &&
                (flags & AudioManager.FLAG_BLUETOOTH_ABS_VOLUME) == 0) {
                synchronized (mA2dpAvrcpLock) {
                    if (mA2dp != null && mAvrcpAbsVolSupported) {
                        mA2dp.adjustAvrcpAbsoluteVolume(direction);
                    }
                }
            }
            if ((direction == AudioManager.ADJUST_RAISE) &&
                    !checkSafeMediaVolume(streamTypeAlias, aliasIndex + step, device)) {
                Log.e(TAG, "adjustStreamVolume() safe volume index = "+oldIndex);
                mVolumePanel.postDisplaySafeVolumeWarning(flags);
            } else if (streamState.adjustIndex(direction * step, device)) {
                // Post message to set system volume (it in turn will post a message
                // to persist). Do not change volume if stream is muted.
                sendMsg(mAudioHandler,
                        MSG_SET_DEVICE_VOLUME,
                        SENDMSG_QUEUE,
                        device,
                        0,
                        streamState,
                        0);
            }
        }
        int index = mStreamStates[streamType].getIndex(device);
        sendVolumeUpdate(streamType, oldIndex, index, flags);
    }

在sendMsg发送Message进入handler中处理，调用setDeviceVolume函数

        private void setDeviceVolume(VolumeStreamState streamState, int device) {
            // Apply volume
            streamState.applyDeviceVolume(device);
            // Apply change to all streams using this one as alias
            int numStreamTypes = AudioSystem.getNumStreamTypes();
            for (int streamType = numStreamTypes - 1; streamType >= 0; streamType--) {
                if (streamType != streamState.mStreamType &&
                        mStreamVolumeAlias[streamType] == streamState.mStreamType) {
                    // Make sure volume is also maxed out on A2DP device for aliased stream
                    // that may have a different device selected
                    int streamDevice = getDeviceForStream(streamType);
                    if ((device != streamDevice) && mAvrcpAbsVolSupported &&
                            ((device & AudioSystem.DEVICE_OUT_ALL_A2DP) != 0)) {
                        mStreamStates[streamType].applyDeviceVolume(device);
                    }
                    mStreamStates[streamType].applyDeviceVolume(streamDevice);
                }
            }
            // Post a persist volume msg
            sendMsg(mAudioHandler,
                    MSG_PERSIST_VOLUME,
                    SENDMSG_QUEUE,
                    device,
                    0,
                    streamState,
                    PERSIST_DELAY);
        }

调用applyDeviceVolume函数

        public void applyDeviceVolume(int device) {
            int index;
            if (isMuted()) {
                index = 0;
            } else if ((device & AudioSystem.DEVICE_OUT_ALL_A2DP) != 0 &&
                       mAvrcpAbsVolSupported) {
                index = (mIndexMax + 5)/10;
            } else {
                index = (getIndex(device) + 5)/10;
            }
    Log.d(TAG,"applyDeviceVolume  index:"+index + " mStreamType:" + mStreamType + ",device:" + device);
            AudioSystem.setStreamVolumeIndex(mStreamType, index, device);
        }

5、调用AudioSystem.java中的setStreamVolumeIndex函数

    public static native int setStreamVolumeIndex(int stream, int index, int device);

6、调用AudioSystem.cpp函数中的setStreamVolumeIndex

status_t AudioSystem::setStreamVolumeIndex(audio_stream_type_t stream,
                                           int index,
                                           audio_devices_t device)
{
    const sp<IAudioPolicyService>& aps = AudioSystem::get_audio_policy_service();
    if (aps == 0) return PERMISSION_DENIED;
    return aps->setStreamVolumeIndex(stream, index, device);
}

7、调用AudioPolicyService.cpp中的setStreamVolumeIndex

status_t AudioPolicyService::setStreamVolumeIndex(audio_stream_type_t stream,
                                                  int index,
                                                  audio_devices_t device)
{
ALOGD("AudioPolicyService::setStreamVolumeIndex");
    if (mpAudioPolicy == NULL) {
        return NO_INIT;
    }
    if (!settingsAllowed()) {
        return PERMISSION_DENIED;
    }
    if (uint32_t(stream) >= AUDIO_STREAM_CNT) {
        return BAD_VALUE;
    }
    Mutex::Autolock _l(mLock);
    if (mpAudioPolicy->set_stream_volume_index_for_device) {
ALOGD("mpAudioPolicy->set_stream_volume_index_for_device");
        return mpAudioPolicy->set_stream_volume_index_for_device(mpAudioPolicy,
                                                                stream,
                                                                index,
                                                                device);
    } else {
    ALOGD("mpAudioPolicy->set_stream_volume_index");
        return mpAudioPolicy->set_stream_volume_index(mpAudioPolicy, stream, index);
    }
}

8、调用AudioMTKPolicyManager.cpp中的setStreamVolumeIndex函数

status_t AudioMTKPolicyManager::setStreamVolumeIndex(AudioSystem::stream_type stream,
                                                      int index,
                                                      audio_devices_t device)
{
    ALOGD("AudioMTKPolicyManager setStreamVolumeIndex stream = %d index = %d device = 0x%x",stream,index,device);
    if ((index < mStreams[stream].mIndexMin) || (index > mStreams[stream].mIndexMax)) {
        return BAD_VALUE;
    }
    if (!audio_is_output_device(device)) {
        return BAD_VALUE;
    }
    // Force max volume if stream cannot be muted
    if (!mStreams[stream].mCanBeMuted) index = mStreams[stream].mIndexMax;
    ALOGV("setStreamVolumeIndex() stream %d, device %04x, index %d",
          stream, device, index);
    // if device is AUDIO_DEVICE_OUT_DEFAULT set default value and
    // clear all device specific values
    if (device == AUDIO_DEVICE_OUT_DEFAULT) {
        mStreams[stream].mIndexCur.clear();
    }
    mStreams[stream].mIndexCur.add(device, index);
#ifdef MTK_AUDIO
#ifdef MTK_AUDIO_GAIN_TABLE
        mAudioUCM->setStreamVolIndex(stream,index,device);
#endif
#endif
    // compute and apply stream volume on all outputs according to connected device
    status_t status = NO_ERROR;
    for (size_t i = 0; i < mOutputs.size(); i++) {
        audio_devices_t curDevice =
                getDeviceForVolume(mOutputs.valueAt(i)->device());
        if ((device == AUDIO_DEVICE_OUT_DEFAULT) || (device == curDevice)) {
#ifdef MTK_AUDIO
            status_t volStatus;
            // alps00053099  adjust matv volume  when record sound stoping, matv sound will out through speaker.
            //  delay  -1 to put this volume command at the end of command queue in audiopolicy service
            if(stream ==AudioSystem::MATV  &&(mAvailableOutputDevices & AudioSystem::DEVICE_OUT_WIRED_HEADSET ||mAvailableOutputDevices & AudioSystem::DEVICE_OUT_WIRED_HEADPHONE))
            {
                volStatus =checkAndSetVolume(stream, index, mOutputs.keyAt(i), curDevice,-1);
            }
            else
            {
                volStatus =checkAndSetVolume(stream, index, mOutputs.keyAt(i), curDevice);
            }
#else
            status_t volStatus = checkAndSetVolume(stream, index, mOutputs.keyAt(i), curDevice);
#endif
            if (volStatus != NO_ERROR) {
                status = volStatus;
            }
        }
    }
    return status;
}

9、真正设置是在checkAndSetVolume函数中执行

status_t AudioMTKPolicyManager::checkAndSetVolume(int stream,
                                                   int index,
                                                   audio_io_handle_t output,
                                                   audio_devices_t device,
                                                   int delayMs,
                                                   bool force)
{
    ALOGD(" checkAndSetVolume stream = %d index = %d output = %d device = 0x%x delayMs = %d force = %d"
        ,stream,index,output,device,delayMs,force);
    // do not change actual stream volume if the stream is muted
    if (mOutputs.valueFor(output)->mMuteCount[stream] != 0) {
        ALOGVV("checkAndSetVolume() stream %d muted count %d",
              stream, mOutputs.valueFor(output)->mMuteCount[stream]);
        return NO_ERROR;
    }
    // do not change in call volume if bluetooth is connected and vice versa
    if ((stream == AudioSystem::VOICE_CALL && mForceUse[AudioSystem::FOR_COMMUNICATION] == AudioSystem::FORCE_BT_SCO) ||
        (stream == AudioSystem::BLUETOOTH_SCO && mForceUse[AudioSystem::FOR_COMMUNICATION] != AudioSystem::FORCE_BT_SCO)) {
        ALOGD("checkAndSetVolume() cannot set stream %d volume with force use = %d for comm",
             stream, mForceUse[AudioSystem::FOR_COMMUNICATION]);
        return INVALID_OPERATION;
    }
    float volume = computeVolume(stream, index, output, device);
ALOGD("checkAndSetVolume volume = %f stream=%d device=%d",volume,stream,device);
    
#ifdef MTK_AUDIO
#ifdef MTK_AUDIO_GAIN_TABLE
    updateAnalogVolume(output,device,delayMs);
#endif
#endif
#ifdef MTK_AUDIO
     //for VT notify tone when incoming call. it's volume will be adusted in hardware.
     if((stream == AudioSystem::VOICE_CALL ||stream == AudioSystem::BLUETOOTH_SCO) && mOutputs.valueFor(output)->mRefCount[stream]!=0 && mPhoneState==AudioSystem::MODE_IN_CALL)
     {
        volume =1.0;
     }
     // ALPS00554824 KH: If notifiaction is exist, FM should be mute
     if ((stream == AudioSystem::FM) &&
        (mOutputs.valueFor(output)->mRefCount[AudioSystem::NOTIFICATION]
         || mOutputs.valueFor(output)->mRefCount[AudioSystem::RING]
         || mOutputs.valueFor(output)->mRefCount[AudioSystem::ALARM]))
     {
        volume =0.0;
     }
    // ALPS001125976 Mute music at ringtone from BT to primary
    //if ( (stream == AudioSystem::MUSIC) && (mPhoneState ==AudioSystem::MODE_RINGTONE) && (mStreams[AudioSystem::RING].getVolumeIndex(device)!=mStreams[AudioSystem::RING].mIndexMin) ) {
    //    volume =0.0;
    //}
#endif
    //ALOGD("checkAndSetVolume newvolume %f, oldvolume %f,output %d",volume,mOutputs.valueFor(output)->mCurVolume[stream],output);
    // We actually change the volume if:
    // - the float value returned by computeVolume() changed
    // - the force flag is set
    if (volume != mOutputs.valueFor(output)->mCurVolume[stream] ||
            force
#ifdef MTK_AUDIO
    ||(stream==AudioSystem::FM && output==mPrimaryOutput && (device == AUDIO_DEVICE_OUT_WIRED_HEADSET ||device == AUDIO_DEVICE_OUT_WIRED_HEADPHONE) )//WFD output can't affect HwGain,however affect mFmVolume . But PrimaryOutput will use mFmVolume setting
#endif
    ) {
#ifdef MTK_AUDIO
        int bSetStreamVolume=1;
        //Overall, Don't set volume to affect direct mode volume setting if the later routing is still direct mode . HoChi . This is very tricky that WFD support FM,others(BT/...) don't.
#ifdef MATV_AUDIO_SUPPORT
if( matv_use_analog_input == true){
            if((stream==AudioSystem::MATV)&&(output!=mPrimaryOutput||device==AUDIO_DEVICE_NONE)&&device!=AUDIO_DEVICE_OUT_REMOTE_SUBMIX){
                bSetStreamVolume=0; //MATV with line-in path is only ouput from primaryoutput
            }
}
#endif
            //Add device==AUDIO_DEVICE_NONE for ALPS
            if((stream==AudioSystem::FM)&&(output!=mPrimaryOutput||device==AUDIO_DEVICE_NONE)&&device!=AUDIO_DEVICE_OUT_REMOTE_SUBMIX){
                bSetStreamVolume=0; //FM with line-in path is only ouput from primaryoutput
            }
        if(bSetStreamVolume==1)
        {
#endif
        mOutputs.valueFor(output)->mCurVolume[stream] = volume;
        ALOGD("checkAndSetVolume() for output %d stream %d, volume %f, delay %d", output, stream, volume, delayMs);
        // Force VOICE_CALL to track BLUETOOTH_SCO stream volume when bluetooth audio is
        // enabled
        if (stream == AudioSystem::BLUETOOTH_SCO) {
            mpClientInterface->setStreamVolume(AudioSystem::VOICE_CALL, volume, output, delayMs);
        }
        mpClientInterface->setStreamVolume((AudioSystem::stream_type)stream, volume, output, delayMs);
#ifdef MTK_AUDIO
        }
        else
        {
            ALOGD("skip setStreamVolume for output %d stream %d, volume %f, delay %d",output, stream, volume, delayMs);
        }
#endif
    }
    ALOGD("checkAndSetVolume() for output %d stream %d, volume %f, delay %d, loc 2", output, stream, volume, delayMs);
    if (stream == AudioSystem::VOICE_CALL ||
        stream == AudioSystem::BLUETOOTH_SCO) {
        float voiceVolume;
        // Force voice volume to max for bluetooth SCO as volume is managed by the headset
        if (stream == AudioSystem::VOICE_CALL) {
#ifdef MTK_AUDIO
#ifndef MTK_AUDIO_GAIN_TABLE
            voiceVolume = computeCustomVoiceVolume(stream, index, output, device);
#endif
#else
            voiceVolume = (float)index/(float)mStreams[stream].mIndexMax;
#endif
        } else {
            voiceVolume = 1.0;
        }
 ALOGD("checkAndSetVolume() voiceVolume %f mLastVoiceVolume %f mPrimaryOutput %d output %d",voiceVolume, mLastVoiceVolume,mPrimaryOutput,output);
        if (voiceVolume != mLastVoiceVolume && output == mPrimaryOutput) {
            mpClientInterface->setVoiceVolume(voiceVolume, delayMs);
#ifdef MTK_AUDIO
#ifdef EVDO_DT_SUPPORT
            ALOGD("SetVoiceVolumeIndex=%d %f,%f,%d", index, voiceVolume, mLastVoiceVolume, output == mPrimaryOutput);            
            //set Volume Index ( for external modem)
            AudioParameter param = AudioParameter();
            param.addInt(String8("SetVoiceVolumeIndex"), index);
            mpClientInterface->setParameters (0 , param.toString(), 0);
#endif
#endif
            mLastVoiceVolume = voiceVolume;
        }
    }
    return NO_ERROR;
}

 if (voiceVolume != mLastVoiceVolume && output == mPrimaryOutput) {
            mpClientInterface->setVoiceVolume(voiceVolume, delayMs);
#ifdef MTK_AUDIO
#ifdef EVDO_DT_SUPPORT
            ALOGD("SetVoiceVolumeIndex=%d %f,%f,%d", index, voiceVolume, mLastVoiceVolume, output == mPrimaryOutput);            
            //set Volume Index ( for external modem)
            AudioParameter param = AudioParameter();
            param.addInt(String8("SetVoiceVolumeIndex"), index);
            mpClientInterface->setParameters (0 , param.toString(), 0);
#endif
#endif
            mLastVoiceVolume = voiceVolume;
        }

函数中经过判断本次音量与上次音量的比较 以及输出设备的比较正确的话，设置到底层

其中之前音量的设置会经过多次的计算，与音频参数等的计算