Android Question Audio Safe Volume

/==========================================================================================
// Safe media volume management.
// MUSIC stream volume level is limited when headphones are connected according to safety
// regulation. When the user attempts to raise the volume above the limit, a warning is
// displayed and the user has to acknowlegde before the volume is actually changed.
// The volume index corresponding to the limit is stored in config_safe_media_volume_index
// property. Platforms with a different limit must set this property accordingly in their
// overlay.
//==========================================================================================

// mSafeMediaVolumeState indicates whether the media volume is limited over headphones.
// It is SAFE_MEDIA_VOLUME_NOT_CONFIGURED at boot time until a network service is connected
// or the configure time is elapsed. It is then set to SAFE_MEDIA_VOLUME_ACTIVE or
// SAFE_MEDIA_VOLUME_DISABLED according to country option. If not SAFE_MEDIA_VOLUME_DISABLED, it
// can be set to SAFE_MEDIA_VOLUME_INACTIVE by calling AudioService.disableSafeMediaVolume()
// (when user opts out).
private final int SAFE_MEDIA_VOLUME_NOT_CONFIGURED = 0;
private final int SAFE_MEDIA_VOLUME_DISABLED = 1;
private final int SAFE_MEDIA_VOLUME_INACTIVE = 2;
private final int SAFE_MEDIA_VOLUME_ACTIVE = 3;
private Integer mSafeMediaVolumeState;

private int mMcc = 0;
// mSafeMediaVolumeIndex is the cached value of config_safe_media_volume_index property
private int mSafeMediaVolumeIndex;
// mSafeMediaVolumeDevices lists the devices for which safe media volume is enforced,
private final int mSafeMediaVolumeDevices = AudioSystem.DEVICE_OUT_WIRED_HEADSET |
AudioSystem.DEVICE_OUT_WIRED_HEADPHONE;
// mMusicActiveMs is the cumulative time of music activity since safe volume was disabled.
// When this time reaches UNSAFE_VOLUME_MUSIC_ACTIVE_MS_MAX, the safe media volume is re-enabled
// automatically. mMusicActiveMs is rounded to a multiple of MUSIC_ACTIVE_POLL_PERIOD_MS.

private int mMusicActiveMs;
private static final int UNSAFE_VOLUME_MUSIC_ACTIVE_MS_MAX = (20 * 3600 * 1000); // 20 hours
private static final int MUSIC_ACTIVE_POLL_PERIOD_MS = 60000; // 1 minute polling interval
private static final int SAFE_VOLUME_CONFIGURE_TIMEOUT_MS = 30000; // 30s after boot completed


private void setSafeMediaVolumeEnabled(boolean on) {
synchronized (mSafeMediaVolumeState) {
if ((mSafeMediaVolumeState != SAFE_MEDIA_VOLUME_NOT_CONFIGURED) &&
(mSafeMediaVolumeState != SAFE_MEDIA_VOLUME_DISABLED)) {
if (on && (mSafeMediaVolumeState == SAFE_MEDIA_VOLUME_INACTIVE)) {
mSafeMediaVolumeState = SAFE_MEDIA_VOLUME_ACTIVE;
enforceSafeMediaVolume();
} else if (!on && (mSafeMediaVolumeState == SAFE_MEDIA_VOLUME_ACTIVE)) {
mSafeMediaVolumeState = SAFE_MEDIA_VOLUME_INACTIVE;
mMusicActiveMs = 0;
sendMsg(mAudioHandler,
MSG_CHECK_MUSIC_ACTIVE,
SENDMSG_REPLACE,
0,
0,
null,
MUSIC_ACTIVE_POLL_PERIOD_MS);
}
}
}
}

mSafeMediaVolumeState = new Integer(Settings.Global.getInt(mContentResolver,
Settings.Global.AUDIO_SAFE_VOLUME_STATE,
SAFE_MEDIA_VOLUME_NOT_CONFIGURED));
// The default safe volume index read here will be replaced by the actual value when
// the mcc is read by onConfigureSafeVolume()