OMXPlayer, MediaSanner, MediaPlayer, VideoView...

OMXPlayer is an Interface Only:
-- framework/base/include/media/OMXPlayer.h

class OMXPlayer : public MediaPlayerInterface
{
public:
                        OMXPlayer(int nMediaType = 0);
    virtual             ~OMXPlayer();

    virtual status_t    initCheck();
    virtual status_t    setDataSource(const char *url, const KeyedVector *headers);
    virtual status_t    setDataSource(int fd, int64_t offset, int64_t length);
    virtual status_t    setVideoSurface(const sp& surface);
    virtual status_t    setVideoSurface(const android::sp& surface);
    virtual status_t    setVideoSurfaceTexture(const android::sp& surfaceTexture);
    virtual status_t    prepare();
    virtual status_t    prepareAsync();
    virtual status_t    start();
    virtual status_t    stop();
    virtual status_t    pause();
    virtual bool        isPlaying();
....

實做的大概是： frameworks/base/media/libmediaplayerservice/MediaPlayerService.cpp

..
實際上，這也是個空殼而已，真的 player 是在 prebuild .so 。在 device 下的 propriety/libs 下有一些 _omx_player_..

---

用較簡單的 Gallery 來看，啟動到最後，是 MovieView.java
這是一個 Activity，onCreate 後就直接播放影片了。

MovieView 只有實做三個 callback:

• onCreate : new MovieViewControl
• onPause : call MovieViewControl.onPause
• onResume : call MovieViewControl.onResume
• onWindowFocusChanged : call MovieViewControl.onResume/li>

Video 播放直接關聯到 VideoView 這個 layout，
在 res/layout/movie_view.xml 中放入一個 object:

    <VideoView android:id="@+id/surface_view"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_centerInParent="true" />

然後在 source:

    private final VideoView mVideoView;
     .....
       mVideoView = (VideoView) rootView.findViewById(R.id.surface_view);
 

取得 VideoView 元件後，就可以對 VideoView 操作：
如果有時作幾個 需要的interface，就可以接著設定：

        mVideoView.setOnErrorListener(this);
        mVideoView.setOnCompletionListener(this);

設定要撥的file (uri)，和 control.

        mVideoView.setVideoURI(mUri);
        mMediaController = new MediaController(context);
        mVideoView.setMediaController(mMediaController);

然後，就可以開始播放：

        mVideoView.start();

---

另外一個是在 development/samples/ApiDemos/src/com/example/android/apis/media/MeduaPlayerDemo_Video.java

還有有關 scanfile 的 sample code，在 development/samples 下也有...
development/samples/ApiDemos/src/com/example/android/apis/content/ExternalStorage.java

這一段code:

        File path = Environment.getExternalStoragePublicDirectory(
                Environment.DIRECTORY_PICTURES);
        File file = new File(path, "DemoPicture.jpg");

        ....
        ....
            // Tell the media scanner about the new file so that it is
            // immediately available to the user.
            MediaScannerConnection.scanFile(this,
                    new String[] { file.toString() }, null,
                    new MediaScannerConnection.OnScanCompletedListener() {
                public void onScanCompleted(String path, Uri uri) {
                    Log.i("ExternalStorage", "Scanned " + path + ":");
                    Log.i("ExternalStorage", "-> uri=" + uri);
                }
            });

所以可以把 file path 丟到這裡scan 轉成 media Uri
?

---

最後拿 developement/sample 的 MediaPlayerDemo_Video.java 來測試。
原來是用 file path，改成用 scan 後的 Uri。

diff 是：

	diff --git a/samples/ApiDemos/src/com/example/android/apis/media/MediaPlayerDemo_Video.java b/samples/ApiDemos/src/com/example/android/apis/media/MediaPlayerDemo_Video.java
	index 9853d67..de5a1ac 100644
	--- a/samples/ApiDemos/src/com/example/android/apis/media/MediaPlayerDemo_Video.java
	+++ b/samples/ApiDemos/src/com/example/android/apis/media/MediaPlayerDemo_Video.java
	@@ -30,9 +30,13 @@ import android.util.Log;
	import android.view.SurfaceHolder;
	import android.view.SurfaceView;
	import android.widget.Toast;
	+import android.media.MediaScannerConnection;
	+import android.net.Uri;
	+import android.content.Context;
	public class MediaPlayerDemo_Video extends Activity implements
	+ MediaScannerConnection.OnScanCompletedListener,
	OnBufferingUpdateListener, OnCompletionListener,
	OnPreparedListener, OnVideoSizeChangedListener, SurfaceHolder.Callback {
	@@ -71,14 +75,12 @@ public class MediaPlayerDemo_Video extends Activity implements
	private void playVideo(Integer Media) {
	doCleanUp();
	- try {
	-
	switch (Media) {
	case LOCAL_VIDEO:
	/*
	* TODO: Set the path variable to a local media file path.
	*/
	- path = "";
	+ path = "/mnt/sdcard/udisk1/batman4.mp4";
	if (path == "") {
	// Tell the user to provide a media file URL.
	Toast
	@@ -118,9 +120,19 @@ public class MediaPlayerDemo_Video extends Activity implements
	}
	- // Create a new media player and set the listeners
	+ MediaScannerConnection.scanFile(this,new String[] {path}, null,this);
	+
	+
	+ }
	+
	+ public void onScanCompleted(String path, Uri uri)
	+ {
	+ Log.i(TAG,"path: " + path);
	+ Log.i(TAG,"uri: " + uri);
	+ try {
	+ // Create a new media player and set the listeners
	mMediaPlayer = new MediaPlayer();
	- mMediaPlayer.setDataSource(path);
	+ mMediaPlayer.setDataSource(getApplicationContext(),uri);
	mMediaPlayer.setDisplay(holder);
	mMediaPlayer.prepare();
	mMediaPlayer.setOnBufferingUpdateListener(this);
	@@ -161,7 +173,7 @@ public class MediaPlayerDemo_Video extends Activity implements
	public void onPrepared(MediaPlayer mediaplayer) {
	Log.d(TAG, "onPrepared called");
	mIsVideoReadyToBePlayed = true;
	- if (mIsVideoReadyToBePlayed && mIsVideoSizeKnown) {
	+ if (mIsVideoReadyToBePlayed /*&& mIsVideoSizeKnown*/) {
	startVideoPlayback();
	}
	}

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