修改系统默认volume_*_speaker的值

【原因分析】

需要修改默认的Audio值和调节范围

music : 0- 15(U50) default: 5 pepito: 0- 15 default: 5 KO 
notification : 0 - 7(U50) default :5 pepito : 0 -15 default: 9 KO 
Alarm : 0 - 7(U50) default :6 pepito : 0 -15 default: 11 KO 
system : 0 - 7(U50) default :5 pepito : 0 -7 default: 5 KO

【解决方案】

• 在/platform/frameworks/base/media/java/android/media/AudioSystem.java　中修改DEFAULT_STREAM_VOLUME数组默认值

    public static int[] DEFAULT_STREAM_VOLUME = new int[] {
        4,  // STREAM_VOICE_CALL
        11,  // STREAM_SYSTEM
        5,  // STREAM_RING
        7, // STREAM_MUSIC
        11,  // STREAM_ALARM
        9,  // STREAM_NOTIFICATION
        7,  // STREAM_BLUETOOTH_SCO
        7,  // STREAM_SYSTEM_ENFORCED
        5, // STREAM_DTMF
        5, // STREAM_TTS
        5, // STREAM_ACCESSIBILITY
    };

• 在platform/frameworks/base/services/core/java/com/android/server/audio/AudioService.java　中修改MAX_STREAM_VOLUME数组范围

private static int[] MAX_STREAM_VOLUME = new int[] {
        8,  // STREAM_VOICE_CALL PR6931858 [email protected] add voice volume level 5-->8
        15,  // STREAM_SYSTEM
        7,  // STREAM_RING
        15, // STREAM_MUSIC
        15,  // STREAM_ALARM
        15,  // STREAM_NOTIFICATION
        15, // STREAM_BLUETOOTH_SCO
        7,  // STREAM_SYSTEM_ENFORCED
        15, // STREAM_DTMF
        15, // STREAM_TTS
        15  // STREAM_ACCESSIBILITY
    };

• 但是需要注意一下，在AudioService.java的构造方法中会重新修改STREAM_MUSIC的默认值。我这边是给ro.config.media_vol_default写入了默认值７，否则就要在下面的方法中手动赋默认值

　　　　int defaultMusicVolume = SystemProperties.getInt("ro.config.media_vol_default", -1);
        if (defaultMusicVolume != -1 &&
                defaultMusicVolume <= MAX_STREAM_VOLUME[AudioSystem.STREAM_MUSIC]) {
            AudioSystem.DEFAULT_STREAM_VOLUME[AudioSystem.STREAM_MUSIC] = defaultMusicVolume;
        } else {
            if (isPlatformTelevision()) {
                AudioSystem.DEFAULT_STREAM_VOLUME[AudioSystem.STREAM_MUSIC] =
                        MAX_STREAM_VOLUME[AudioSystem.STREAM_MUSIC] / 4;
            } else {
                AudioSystem.DEFAULT_STREAM_VOLUME[AudioSystem.STREAM_MUSIC] =
                        MAX_STREAM_VOLUME[AudioSystem.STREAM_MUSIC] / 3;
            }