Android Soundpool problems

Question

I've got an app on the Android Market and have been using the SoundPool classes for the sound effects. I've noticed that, of all the parts of the Android API, this seems to have caused me the most problems. For example:

• HTC Desire has problems playing WAV files (this causes it to lock up randomly). Using .ogg files fixes this

• On the Droid, if you exceed the number of channels in the init setup call:

mSoundPool = new SoundPool(4, AudioManager.STREAM_MUSIC, 0);

the handset would lock up. If you can imagine the difficulty in debugging that! On a handset I don't own. It required a lot of selfless help from my customers. Changing the '4' to '16' eliminated the problem. I have no doubt that if 16 sounds were played simultaneously it would still crash. Thankfully the chances of that are low.

• Also getting random crashes on various devices. I have got a catlog from one of my customers which has 'Heap overflow' errors pertaining to playing sounds.

I have now changed my sound manager to use MediaPlayer. This seems to be working out fine for now. I am just wondering if any other developers are experiencing these problems?

Answer 1

It seems AudioFlinger can have up to 1 Mb worth of audio going on at any given time. The heap errors occur if this limit is exceeded. This guess is based on some code I found in AudioFlinger source code:

AudioFlinger::Client::Client(const sp<AudioFlinger>& audioFlinger, pid_t pid) 
     :   RefBase(), 
         mAudioFlinger(audioFlinger), 
         mMemoryDealer(new MemoryDealer(1024*1024)), 
         mPid(pid) 
{ 
     // 1 MB of address space is good for 32 tracks, 8 buffers each, 4 KB/buffer 
} 

And this:

size_t size = sizeof(audio_track_cblk_t); 
size_t bufferSize = frameCount*channelCount*sizeof(int16_t); 
if (sharedBuffer == 0) { 
    size += bufferSize; 
} 
mCblkMemory = client->heap()->allocate(size); 
if (mCblkMemory != 0) {
    ...
} else {
    LOGE("not enough memory for AudioTrack size=%u", size); 
    client->heap()->dump("AudioTrack"); 
}

Anyone else better informed?