Android Audio代码分析19 - setPosition函数

之前我们看过get position，今天来看看set position。

*****************************************源码*************************************************
    //Test case 3: setPlaybackHeadPosition() on paused track
    @LargeTest
    public void testSetPlaybackHeadPositionPaused() throws Exception {
        // constants for test
        final String TEST_NAME = "testSetPlaybackHeadPositionPaused";
        final int TEST_SR = 22050;
        final int TEST_CONF = AudioFormat.CHANNEL_OUT_MONO;
        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,
                2*minBuffSize, TEST_MODE);
        byte data[] = new byte[minBuffSize];
        //--------    test        --------------
        assumeTrue(TEST_NAME, track.getState() == AudioTrack.STATE_INITIALIZED);
        track.write(data, 0, data.length);
        track.write(data, 0, data.length);
        track.play();
        track.pause();
        assumeTrue(TEST_NAME, track.getPlayState() == AudioTrack.PLAYSTATE_PAUSED);
        assertTrue(TEST_NAME, track.setPlaybackHeadPosition(10) == 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 3: setPlaybackHeadPosition() on paused track
    @LargeTest
    public void testSetPlaybackHeadPositionPaused() throws Exception {
        // constants for test
        final String TEST_NAME = "testSetPlaybackHeadPositionPaused";
        final int TEST_SR = 22050;
        final int TEST_CONF = AudioFormat.CHANNEL_OUT_MONO;
        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,
                2*minBuffSize, TEST_MODE);
        byte data[] = new byte[minBuffSize];
        //--------    test        --------------
        assumeTrue(TEST_NAME, track.getState() == AudioTrack.STATE_INITIALIZED);
        track.write(data, 0, data.length);
        track.write(data, 0, data.length);
        track.play();
        track.pause();
        assumeTrue(TEST_NAME, track.getPlayState() == AudioTrack.PLAYSTATE_PAUSED);
        assertTrue(TEST_NAME, track.setPlaybackHeadPosition(10) == AudioTrack.SUCCESS);
+++++++++++++++++++++++++++++setPlaybackHeadPosition+++++++++++++++++++++++++++++++++++
    /**
     * Sets the playback head position. The track must be stopped for the position to be changed.
     * @param positionInFrames playback head position expressed in frames
     * @return error code or success, see {@link #SUCCESS}, {@link #ERROR_BAD_VALUE},
     *    {@link #ERROR_INVALID_OPERATION}
     */
    public int setPlaybackHeadPosition(int positionInFrames) {
        synchronized(mPlayStateLock) {
            if ((mPlayState == PLAYSTATE_STOPPED) || (mPlayState == PLAYSTATE_PAUSED)) {
                return native_set_position(positionInFrames);
++++++++++++++++++++++++++++android_media_AudioTrack_set_position++++++++++++++++++++++++++++++++++++
static jint android_media_AudioTrack_set_position(JNIEnv *env, jobject thiz,
        jint position) {

    AudioTrack *lpTrack = (AudioTrack *)env->GetIntField(
                thiz, javaAudioTrackFields.nativeTrackInJavaObj);

    if (lpTrack) {
        return android_media_translateErrorCode( lpTrack->setPosition(position) );
++++++++++++++++++++++++++++AudioTrack::setPosition++++++++++++++++++++++++++++++++++++
status_t AudioTrack::setPosition(uint32_t position)
{
    Mutex::Autolock _l(mCblk->lock);

if (!stopped()) return INVALID_OPERATION;

if (position > mCblk->user) return BAD_VALUE;

mCblk->server = position;
mCblk->flags |= CBLK_FORCEREADY_ON;

    return NO_ERROR;
}
----------------------------AudioTrack::setPosition------------------------------------
    } else {
     &

补充：移动开发 , Android ,