Android Audio代码分析18 - setSampleRate函数
今天来看看playback rate相关的接口。包括set和get。
*****************************************源码*************************************************
//Test case 6: setPlaybackRate() accepts values twice the output sample rate
@LargeTest
public void testSetPlaybackRateTwiceOutputSR() throws Exception {
// constants for test
final String TEST_NAME = "testSetPlaybackRateTwiceOutputSR";
final int TEST_SR = 22050;
final int TEST_CONF = AudioFormat.CHANNEL_OUT_STEREO;
final int TEST_FORMAT = AudioFormat.ENCODING_PCM_16BIT;
final int TEST_MODE = AudioTrack.MODE_STREAM;
final int TEST_STREAM_TYPE = AudioManager.STREAM_MUSIC;
//-------- initialization --------------
int minBuffSize = AudioTrack.getMinBufferSize(TEST_SR, TEST_CONF, TEST_FORMAT);
AudioTrack track = new AudioTrack(TEST_STREAM_TYPE, TEST_SR, TEST_CONF, TEST_FORMAT,
minBuffSize, TEST_MODE);
byte data[] = new byte[minBuffSize/2];
int outputSR = AudioTrack.getNativeOutputSampleRate(TEST_STREAM_TYPE);
//-------- test --------------
track.write(data, 0, data.length);
track.write(data, 0, data.length);
assumeTrue(TEST_NAME, track.getState() == AudioTrack.STATE_INITIALIZED);
track.play();
assertTrue(TEST_NAME, track.setPlaybackRate(2*outputSR) == AudioTrack.SUCCESS);
//-------- tear down --------------
track.release();
}
**********************************************************************************************
源码路径：
frameworks\base\media\tests\mediaframeworktest\src\com\android\mediaframeworktest\functional\MediaAudioTrackTest.java
#######################说明################################
//Test case 6: setPlaybackRate() accepts values twice the output sample rate
@LargeTest
public void testSetPlaybackRateTwiceOutputSR() throws Exception {
// constants for test
final String TEST_NAME = "testSetPlaybackRateTwiceOutputSR";
final int TEST_SR = 22050;
final int TEST_CONF = AudioFormat.CHANNEL_OUT_STEREO;
final int TEST_FORMAT = AudioFormat.ENCODING_PCM_16BIT;
final int TEST_MODE = AudioTrack.MODE_STREAM;
final int TEST_STREAM_TYPE = AudioManager.STREAM_MUSIC;
//-------- initialization --------------
int minBuffSize = AudioTrack.getMinBufferSize(TEST_SR, TEST_CONF, TEST_FORMAT);
AudioTrack track = new AudioTrack(TEST_STREAM_TYPE, TEST_SR, TEST_CONF, TEST_FORMAT,
minBuffSize, TEST_MODE);
byte data[] = new byte[minBuffSize/2];
int outputSR = AudioTrack.getNativeOutputSampleRate(TEST_STREAM_TYPE);
+++++++++++++++++++++++++++++getNativeOutputSampleRate+++++++++++++++++++++++++++++++++++
/**
* Returns the hardware output sample rate
*/
static public int getNativeOutputSampleRate(int streamType) {
return native_get_output_sample_rate(streamType);
+++++++++++++++++++++++++++++android_media_AudioTrack_get_playback_rate+++++++++++++++++++++++++++++++++++
static jint android_media_AudioTrack_get_playback_rate(JNIEnv *env, jobject thiz) {
AudioTrack *lpTrack = (AudioTrack *)env->GetIntField(
thiz, javaAudioTrackFields.nativeTrackInJavaObj);
if (lpTrack) {
return (jint) lpTrack->getSampleRate();
++++++++++++++++++++++++++++AudioTrack::getSampleRate++++++++++++++++++++++++++++++++++++
uint32_t AudioTrack::getSampleRate()
{
// 直接返回了audio_track_cblk_t中的sample rate。
// audio_track_cblk_t对象在AudioFlinger::ThreadBase::TrackBase::TrackBase的构造函数中被创建：new(mCblk) audio_track_cblk_t();
// 创建audio_track_cblk_t对象后，即对其成员变量sampleRate进行了赋值：mCblk->sampleRate = sampleRate;
// 此处的sampleRate其实是创建AudioTrack对象时传入的sampleRate。
return mCblk->sampleRate;
}
----------------------------AudioTrack::getSampleRate------------------------------------
} else {
jniThrowException(env, "java/lang/IllegalStateException",
"Unable to retrieve AudioTrack pointer for getSampleRate()");
return AUDIOTRACK_ERROR;
}
}
-----------------------------android_media_AudioTrack_get_playback_rate-----------------------------------
}
-----------------------------getNativeOutputSampleRate-----------------------------------
//-------- test --------------
track.write(data, 0, data.length);
track.write(data, 0, data.length);
assumeTrue(TEST_NAME, track.getState() == AudioTrack.STATE_INITIALIZED);
track.play();
assertTrue(TEST_NAME, track.setPlaybackRate(2*outputSR) == AudioTrack.SUCCESS);
++++++++++++++++++++++++++++setPlaybackRate+++++++++++++++++++++++++++++++++++
/**
* Sets the playback sample rate for this track. This sets the sampling rate at which
* the audio data will be consumed and played back, not the original sampling rate of the
&n
补充：移动开发 , Android ,
