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AudioAPI: updates for AudioTrack methods

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There are several changes in the commit:

1. Use instance methods to get sample rate and buffer size info
on Android N or above only instead of Android M, since both
AudioAttributes.FLAG_LOW_LATENCY (256) and the implicitly used
AudioFormat.SAMPLE_RATE_UNSPECIFIED (0) are available only since
API 24 (N).

2. Use setPerformanceMode() on Android O, as FLAG_LOW_LATENCY is
deprecated since API 26 (O).

3. Create AudioTrack instance of both the fast (LOW_LATENCY) and
deep buffer (POWER_SAVING) mixer path. The two paths can be using
different subdevices on different rate and buffer size (or same
subdevice on same rate but different buffer size). For example on
my phone:

AUDIOTRACK_SAMPLE_RATE: 192000
AUDIOTRACK_BUFFER_SIZE_IN_FRAMES: 23046
AUDIOTRACK_SAMPLE_RATE_LOW_LATENCY: 48000
AUDIOTRACK_BUFFER_SIZE_IN_FRAMES_LOW_LATENCY: 192

4. Get info on sample rate with the getNativeOutputSampleRate()
static method (static in Java's sense; the value is still sink-
based) on builds older than N only. The rate appears to be of the
fast (LOW_LATENCY) mixer path if it is available.

5. A note on the static method getMinBufferSize(). The reason it
is not used even for older devices is, it returns buffer size info
of the deep buffer (POWER_SAVING) mixer path, while NOSR is the
rate of the fast (LOW_LATENCY) mixer path, so the value we can get
with it is not always sensical.
This commit is contained in:
Tom Yan 2018-04-04 16:04:57 +08:00 committed by Fredrik Fornwall
parent 299d55789b
commit 34c6841a05
1 changed files with 53 additions and 20 deletions
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73
app/src/main/java/com/termux/api/AudioAPI.java
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@ -3,7 +3,6 @@ package com.termux.api;
import android.content.Context;
import android.content.Intent;
import android.media.AudioAttributes;
import android.media.AudioFormat;
import android.media.AudioManager;
import android.media.AudioTrack;
import android.os.Build;
@ -22,25 +21,53 @@ public class AudioAPI {
final int maxvolume_level = am.getStreamMaxVolume(AudioManager.STREAM_MUSIC);
final boolean bluetootha2dp = am.isBluetoothA2dpOn();
final boolean wiredhs = am.isWiredHeadsetOn();
final int nativeoutput = AudioTrack.getNativeOutputSampleRate(AudioManager.STREAM_MUSIC);
int _bs = 0;
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
AudioTrack at = new AudioTrack(
new AudioAttributes.Builder()
.setFlags(256) // FLAG_LOW_LATENCY
.build(),
new AudioFormat.Builder()
.build(),
4, // bytes; i.e. one 16bit 2ch frame
AudioTrack.MODE_STREAM,
AudioManager.AUDIO_SESSION_ID_GENERATE
);
_bs = at.getBufferSizeInFrames();
//final int bc = at.getBufferCapacityInFrames(); only available api 24 and up and apparently
// always returns same value as the initial getbuffersizeinframes.
at.release();
int _sr, _bs, _sr_ll, _bs_ll, _nosr;
_sr = _bs = _sr_ll = _bs_ll = _nosr = 0;
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
int[] modes = {AudioTrack.PERFORMANCE_MODE_POWER_SAVING,
AudioTrack.PERFORMANCE_MODE_LOW_LATENCY};
for (int mode: modes) {
AudioTrack at = new AudioTrack.Builder()
.setBufferSizeInBytes(4) // one 16bit 2ch frame
.setPerformanceMode(mode)
.build();
if (mode == AudioTrack.PERFORMANCE_MODE_POWER_SAVING) {
_sr = at.getSampleRate();
_bs = at.getBufferSizeInFrames();
} else if (mode == AudioTrack.PERFORMANCE_MODE_LOW_LATENCY) {
_sr_ll = at.getSampleRate();
_bs_ll = at.getBufferSizeInFrames();
}
at.release();
}
} else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
int[] flags = {0,AudioAttributes.FLAG_LOW_LATENCY};
for (int flag: flags) {
AudioAttributes aa = new AudioAttributes.Builder()
.setFlags(flag)
.build();
AudioTrack at = new AudioTrack.Builder()
.setAudioAttributes(aa)
.setBufferSizeInBytes(4) // one 16bit 2ch frame
.build();
if (flag == 0) {
_sr = at.getSampleRate();
_bs = at.getBufferSizeInFrames();
} else if (flag == AudioAttributes.FLAG_LOW_LATENCY) {
_sr_ll = at.getSampleRate();
_bs_ll = at.getBufferSizeInFrames();
}
at.release();
}
} else {
_nosr = AudioTrack.getNativeOutputSampleRate(AudioManager.STREAM_MUSIC);
}
final int sr = _sr;
final int bs = _bs;
final int sr_ll = _sr_ll;
final int bs_ll = _bs_ll;
final int nosr = _nosr;
ResultReturner.returnData(apiReceiver, intent, new ResultReturner.ResultJsonWriter() {
public void writeJson(JsonWriter out) throws Exception {
@ -52,9 +79,15 @@ public class AudioAPI {
out.name("STREAM_MUSIC_MAXVOLUME").value(maxvolume_level);
out.name("BLUETOOTH_A2DP_IS_ON").value(bluetootha2dp);
out.name("WIREDHEADSET_IS_CONNECTED").value(wiredhs);
out.name("CURRENT_NATIVE_OUTPUT_SAMPLERATE").value(nativeoutput);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
out.name("AUDIOTRACK_SAMPLE_RATE").value(sr);
out.name("AUDIOTRACK_BUFFER_SIZE_IN_FRAMES").value(bs);
if (sr_ll != sr || bs_ll != bs) { // all or nothing
out.name("AUDIOTRACK_SAMPLE_RATE_LOW_LATENCY").value(sr_ll);
out.name("AUDIOTRACK_BUFFER_SIZE_IN_FRAMES_LOW_LATENCY").value(bs_ll);
}
} else {
out.name("AUDIOTRACK_NATIVE_OUTPUT_SAMPLE_RATE").value(nosr);
}
out.endObject();
}