Giampaolo
Thanks for yoru reply, but that's definitely not the problem. In fact
what you suggest is what I already do. doInBackground is only called
once and System.gc gets called once before the recording starts. The
call audioRecord.read blocks until the appropriate number of bytes is
read. Ive tried this as an alternative:
buffer = new byte[bufferSize];
int startAt = 0;
int minBufferSize =
AudioRecord.getMinBufferSize(sampleRate,
AudioFormat.CHANNEL_CONFIGURATION_MONO,
AudioFormat.ENCODING_PCM_16BIT);
audioRecord = new
AudioRecord(MediaRecorder.AudioSource.MIC, sampleRate,
AudioFormat.CHANNEL_CONFIGURATION_MONO,
AudioFormat.ENCODING_PCM_16BIT, bufferSize);
audioRecord.startRecording();
int bufferReadResult = 0;
while (startAt < bufferSize)
{
int toRead = 0;
if (startAt + minBufferSize >= bufferSize)
{
toRead = bufferSize - startAt;
}
else
{
toRead = minBufferSize;
}
System.out.println("Starting at " + startAt + "
reading " + toRead + " bytes");
bufferReadResult = audioRecord.read(buffer, startAt,
toRead);
System.out.println("Read " + bufferReadResult + "
bytes");
if (bufferReadResult ==
AudioRecord.ERROR_INVALID_OPERATION)
{
message = "ERROR_INVALID_OPERATION returned";
error = true;
break;
}
if (bufferReadResult == AudioRecord.ERROR_BAD_VALUE)
{
message = "ERROR_BAD_VALUE returned";
error = true;
break;
}
if (bufferReadResult != toRead)
{
message = "Requested " + toRead + " bytes but read
" + bufferReadResult + " bytes";
error = true;
}
startAt += bufferReadResult;
}
This works fine (as does the previous code) on my HTC desire. I'm
waiting for some feedback from my Lg Ally user to let me know if it
works on his phone. If so, problem solved. If not, I'll remove the
lines:
if (bufferReadResult != toRead)
{
message = "Requested " + toRead + " bytes but read
" + bufferReadResult + " bytes";
error = true;
}
And see if that works. Not all Android phones work the same it would
appear.
Bryan
On Jul 31, 7:47 pm, "Giampaolo Tomassoni" <[email protected]>
wrote:
> > protected Void doInBackground(Void... arg0)
> > {
> > System.out.println("Recording started");
> > audioRecord = null;
> > System.gc();
> > int totalBytes = bufferSize;
> > try
> > {
> > buffer = new byte[bufferSize];
>
> I'm not an Android expert, nevertheless I have the feeling that the problem
> is in the System.gc() -> new byte[bufferSize] sequence, which seems to me is
> invoked at every sample cycle.
>
> In many VM, System.gc() may be a performance killer. It may be this applies
> to theLGAlly, too.
>
> If this is the case, the duration of your sampling cycle may be too long to
> sustain the sampling rate, such that the device's hardware buffer gets
> overrun. Then, you're always fetching the maximum size of it, which in case
> of theLGAllycould even be 1024 bytes. If your sampling cycle is long
> enough, you can experience this effect regardless of the sampling rate you
> use.
>
> Instead of a "System.gc()" followed by a "new byte[]", I would instead
> suggest to pre-allocate the byte array and possibly every other memory
> resource you need to perform your task.
>
> Giampaolo
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