Hi, Ok here's two simple example (sine wave) tone generators, one uses the 'streaming' method and the other uses the 'static' method, this relates to how the associated memory is allocated / managed.
The information / tradeoffs - 'streaming' is useful where sounds might be changed dynamically as they are being played, where they are long duration more than a few seconds, not suitable for allocating a large amount of static memory, where you don't mind having some latency before sound is heard, don't need to be synchronized accurately with an animation for example. 'static' is suitable for short duration sounds, don't require a lot of memory, have less latency, are somewhat easier to synchronize. That said, 'streaming' is usually adequate for most ordinary purposes where accuracy < 100ms is not important, such as in a countdown timer before a camera shutter is fired. These are just java examples, high performance low(er) latency sounds would probably use C/C++ code / libraries, eg as discussed here http://superpowered.com/androidaudiopathlatency If you hear a 'clicking' sound after each tone is played try adding code to dynamically reduce the volume (or amplitude) before stopping the AudioTrack... Regards private void playToneStreaming(final int frequency, final long duration) // duration in milliseconds { new Thread(new Runnable() { @Override public void run() { try { final int sampleRate = 8000; final int amplitude = 32000; final double twoPI = Math.PI * 2.0; int minBufferSize = AudioTrack.getMinBufferSize(sampleRate, AudioFormat.CHANNEL_OUT_MONO, AudioFormat.ENCODING_PCM_16BIT); final AudioTrack audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC, sampleRate, AudioFormat.CHANNEL_OUT_MONO, AudioFormat.ENCODING_PCM_16BIT, minBufferSize, AudioTrack.MODE_STREAM); int sampleSize = minBufferSize / 2; short samples[] = new short[sampleSize]; double phase = 0.0; audioTrack.setStereoVolume(1, 1); audioTrack.play(); long end = System.currentTimeMillis() + duration; while (System.currentTimeMillis() < end) { for (int i = 0; i < sampleSize; i++) { phase += twoPI * frequency / sampleRate; samples[i] = (short) (amplitude * Math.sin(phase)); } audioTrack.write(samples, 0, sampleSize); } audioTrack.setStereoVolume(0, 0); audioTrack.stop(); audioTrack.release(); } catch (Exception e) { e.printStackTrace(); } } }).start(); } private void playToneStatic(final int frequency, final long duration) // duration in milliseconds { new Thread(new Runnable() { @Override public void run() { try { final int sampleRate = 8000; final int amplitude = 32000; final double twoPI = Math.PI * 2.0; int sampleSize = (sampleRate / 1000) * (int) duration; short samples[] = new short[sampleSize]; double phase = 0.0; for (int i = 0; i < sampleSize; i++) { phase += twoPI * frequency / sampleRate; samples[i] = (short) (amplitude * Math.sin(phase)); } final AudioTrack audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC, sampleRate, AudioFormat.CHANNEL_OUT_MONO, AudioFormat.ENCODING_PCM_16BIT, sampleSize * 2, AudioTrack.MODE_STATIC); audioTrack.write(samples, 0, sampleSize); audioTrack.setStereoVolume(1, 1); audioTrack.play(); try { Thread.sleep(duration); } catch (Exception ignore) { } audioTrack.setStereoVolume(0, 0); audioTrack.stop(); audioTrack.release(); } catch (Exception e) { e.printStackTrace(); } } }).start(); } private void testTones() { new Thread(new Runnable() { @Override public void run () { long sleep = 500; for ( int frequency = 3000; frequency >= 300; frequency -= 300 ) { playToneStreaming(frequency, sleep); try { Thread.sleep(sleep); } catch (Exception ignore) { } if ( frequency < 1000 ) { sleep = 250; } } sleep = 500; for ( int frequency = 3000; frequency >= 300; frequency -= 300 ) { playToneStatic(frequency, sleep); try { Thread.sleep(sleep); } catch (Exception ignore) { } if ( frequency < 1000 ) { sleep = 250; } } } }).start(); } On Tuesday, December 22, 2015 at 5:25:07 AM UTC+11, David Karr wrote: > > On Sunday, December 20, 2015 at 11:27:14 PM UTC-8, gjs wrote: >> >> Hi, >> >> Here's some examples of using AudioTrack >> http://www.programcreek.com/java-api-examples/index.php?api=android.media.AudioTrack >> >> Just be sure to run in a separate thread. >> >> Regards >> > > Note that I did already say that I'd found multiple ways to do this, and I > was looking for advice on the actual best (or at least better) way to do > this, and you pointed me to a selection of choices, with no information on > tradeoffs. > > In any case, I tried the first one (creating an AudioTrack and then > playing it), and wrapping it with a Runnable and a started Thread, and I > heard no sound from my device when the code executed. > > If it matters, here's the method I ended up with: > > private void playTone() { > new Thread(new Runnable() { > @Override > public void run() { > int minSize = AudioTrack.getMinBufferSize(8000, > AudioFormat.CHANNEL_CONFIGURATION_MONO, AudioFormat.ENCODING_PCM_16BIT); > AudioTrack audioTrack = new > AudioTrack(AudioManager.STREAM_MUSIC, 8000, > AudioFormat.CHANNEL_CONFIGURATION_MONO, > AudioFormat.ENCODING_PCM_16BIT, minSize, > AudioTrack.MODE_STREAM); > audioTrack.play(); > } > }).start(); > } > > > > -- You received this message because you are subscribed to the Google Groups "Android Developers" group. 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