I'm playing WAVs on my Android phone by loading the file and feeding the bytes into AudioTrack.write() via the FileInputStream BufferedInputStream DataInputStream method. The audio plays fine and when it is, I can easily adjust sample rate, volume, etc on the fly with nice performance. However, it's taking about two full seconds for a track to start playing. I know AudioTrack has an inescapable delay, but this is ridiculous. Every time I play a track, I get this:
03-13 14:55:57.100: WARN/AudioTrack(3454): obtainBuffer timed out (is the CPU pegged?) 0x2e9348 user=00000960, server=00000000
03-13 14:55:57.340: WARN/AudioFlinger(72): write blocked for 233 msecs, 9 delayed writes, thread 0xba28
I've noticed that the delayed write count increases by one every time I play a track -- even across multiple sessions -- from the time the phone has been turned on. The block time is always 230 - 240ms, which makes sense considering a minimum buffer size of 9600 on this device (9600 / 44100). I've seen this message in countless searches on the Internet, but it usually seems to be related to not playing audio at all or skipping audio. In my case, it's just a delayed start.
I'm running all my code in a high priority thread. Here's a truncated-yet-functional version of what I'm doing. This is the thread callback in my playback class. Again, this works (only playing 16-bit, 44.1kHz, stereo files right now), it just takes forever to start and has that obtainBuffer/delayed write message every time.
public void run()
{
// Load file
FileInputStream mFileInputStream;
try
{
// mFile is instance of custom file class -- this is correct,
// so don't sweat this line
mFileInputStream = new FileInputStream(mFile.path());
} catch (FileNotFoundException e) {}
BufferedInputStream mBufferedInputStream = new BufferedInputStream(mFileInputStream, mBufferLength);
DataInputStream mDataInputStream = new DataInputStream(mBufferedInputStream);
// Skip header
try
{
if (mDataInputStream.available() > 44)
mDataInputStream.skipBytes(44);
} catch (IOException e) {}
// Initialize device
mAudioTrack = new AudioTrack(AudioManager.STREAM_MUSIC, ConfigManager.SAMPLE_RATE, AudioFormat.CHANNEL_CONFIGURATION_STEREO, AudioFormat.ENCODING_PCM_16BIT, ConfigManager.AUDIO_BUFFER_LENGTH,
AudioTrack.MODE_STREAM);
mAudioTrack.play();
// Initialize buffer
byte[] mByteArray = new byte[mBufferLength];
int mBytesToWrite = 0;
int mBytesWritten = 0;
// Loop to keep thread running
while (mRun)
{
// This flag is turned on when the user presses "play"
while (mPlaying)
{
try
{
// Check if data is available
if (mDataInputStream.available() > 0)
{
// Read data from file and write to audio device
mBytesToWrite = mDataInputStream.read(mByteArray, 0, mBufferLength);
mBytesWritten += mAudioTrack.write(mByteArray, 0, mBytesToWrite);
}
}
catch (IOException e)
{
}
}
}
}
If I can get past the artificially long lag, I can easily deal with the inherit latency by starting my write at a later, predictable position (ie, skip past the minimum buffer length when I start playing a file).
