Android sound focus ---- adjust the volume of Music from Music back to Luncher
Sound types are defined in the AudioSystem. java file.
/* The default audio stream */public static final int STREAM_DEFAULT = -1;/* The audio stream for phone calls */public static final int STREAM_VOICE_CALL = 0;/* The audio stream for system sounds */public static final int STREAM_SYSTEM = 1;/* The audio stream for the phone ring and message alerts */public static final int STREAM_RING = 2;/* The audio stream for music playback */public static final int STREAM_MUSIC = 3;/* The audio stream for alarms */public static final int STREAM_ALARM = 4;/* The audio stream for notifications */public static final int STREAM_NOTIFICATION = 5;/* @hide The audio stream for phone calls when connected on bluetooth */public static final int STREAM_BLUETOOTH_SCO = 6;/* @hide The audio stream for enforced system sounds in certain countries (e.g camera in Japan) */public static final int STREAM_SYSTEM_ENFORCED = 7;/* @hide The audio stream for DTMF tones */public static final int STREAM_DTMF = 8;/* @hide The audio stream for text to speech (TTS) */public static final int STREAM_TTS = 9;
Under normal circumstances, STREAM_MUSIC is used to adjust the volume on the audio and video interfaces, and STREAM_VOICE_CALL is used to return to Luncher, but StreamOverride is delayed. sDelayMs, which can be adjusted immediately after the audio and video interfaces are exited. The size of STREAM_MUSIC is changed ,:
/** * For code clarity for getActiveStreamType(int) * @param delay_ms max time since last STREAM_MUSIC activity to consider * @return true if STREAM_MUSIC is active in streams handled by AudioFlinger now or * in the last "delay_ms" ms. */ private boolean isAfMusicActiveRecently(int delay_ms) { return AudioSystem.isStreamActive(AudioSystem.STREAM_MUSIC, delay_ms) || AudioSystem.isStreamActiveRemotely(AudioSystem.STREAM_MUSIC, delay_ms); } private int getActiveStreamType(int suggestedStreamType) { switch (mPlatformType) { case PLATFORM_VOICE: if (isInCommunication()) { if (AudioSystem.getForceUse(AudioSystem.FOR_COMMUNICATION) == AudioSystem.FORCE_BT_SCO) { // Log.v(TAG, "getActiveStreamType: Forcing STREAM_BLUETOOTH_SCO..."); return AudioSystem.STREAM_BLUETOOTH_SCO; } else { // Log.v(TAG, "getActiveStreamType: Forcing STREAM_VOICE_CALL..."); return AudioSystem.STREAM_VOICE_CALL; } } else if (suggestedStreamType == AudioManager.USE_DEFAULT_STREAM_TYPE) { if (isAfMusicActiveRecently(StreamOverride.sDelayMs)) { if (DEBUG_VOL) Log.v(TAG, "getActiveStreamType: Forcing STREAM_MUSIC stream active"); return AudioSystem.STREAM_MUSIC; } else { if (DEBUG_VOL) Log.v(TAG, "getActiveStreamType: Forcing STREAM_RING b/c default"); return AudioSystem.STREAM_RING; } } else if (isAfMusicActiveRecently(0)) { if (DEBUG_VOL) Log.v(TAG, "getActiveStreamType: Forcing STREAM_MUSIC stream active"); return AudioSystem.STREAM_MUSIC; } break; case PLATFORM_TELEVISION: if (suggestedStreamType == AudioManager.USE_DEFAULT_STREAM_TYPE) { // TV always defaults to STREAM_MUSIC return AudioSystem.STREAM_MUSIC; } break; default: if (isInCommunication()) { if (AudioSystem.getForceUse(AudioSystem.FOR_COMMUNICATION) == AudioSystem.FORCE_BT_SCO) { if (DEBUG_VOL) Log.v(TAG, "getActiveStreamType: Forcing STREAM_BLUETOOTH_SCO"); return AudioSystem.STREAM_BLUETOOTH_SCO; } else { if (DEBUG_VOL) Log.v(TAG, "getActiveStreamType: Forcing STREAM_VOICE_CALL"); return AudioSystem.STREAM_VOICE_CALL; } } else if (AudioSystem.isStreamActive(AudioSystem.STREAM_NOTIFICATION, StreamOverride.sDelayMs) || AudioSystem.isStreamActive(AudioSystem.STREAM_RING, StreamOverride.sDelayMs)) { if (DEBUG_VOL) Log.v(TAG, "getActiveStreamType: Forcing STREAM_NOTIFICATION"); return AudioSystem.STREAM_NOTIFICATION; } else if (suggestedStreamType == AudioManager.USE_DEFAULT_STREAM_TYPE) { if (isAfMusicActiveRecently(StreamOverride.sDelayMs)) { if (DEBUG_VOL) Log.v(TAG, "getActiveStreamType: forcing STREAM_MUSIC"); return AudioSystem.STREAM_MUSIC; } else { if (DEBUG_VOL) Log.v(TAG, "getActiveStreamType: using STREAM_NOTIFICATION as default"); return AudioSystem.STREAM_NOTIFICATION; } } break; } if (DEBUG_VOL) Log.v(TAG, "getActiveStreamType: Returning suggested type " + suggestedStreamType); return suggestedStreamType; }
Change isAfMusicActiveRecently (StreamOverride. sDelayMs) to isAfMusicActiveRecently (0) or a small value.