BlackBerry 视频录制编程概述 BlackBerry 5.0 平台以及之前的版本对多媒体的支持依赖于 JSR 135, 也就是标准 J2ME 平台的 MMAPI BlackBerry 手机上录制视频也依靠 MMAPI, 支持 3gpp 视频格式, 支持的视频编码包括 MPEG-4, H263

Size: px

Start display at page:

Download "BlackBerry 视频录制编程概述 BlackBerry 5.0 平台以及之前的版本对多媒体的支持依赖于 JSR 135, 也就是标准 J2ME 平台的 MMAPI BlackBerry 手机上录制视频也依靠 MMAPI, 支持 3gpp 视频格式, 支持的视频编码包括 MPEG-4, H263"

巍衔戈窦
5 years ago
Views:

1 BlackBerry 视频录制编程作者 : 俞伟目录 BlackBerry 视频录制编程概述... 2 获取 / 选定视频格式 / 编码... 2 录制存储视频... 5 回放已录制的视频... 8 完整代码类 VideoRecordingScreen.java 类 VideoRecordingSetupScreen.java 类 VideoPlaybackScreen.java 类 VideoRecordingDemo.java

2 BlackBerry 视频录制编程概述 BlackBerry 5.0 平台以及之前的版本对多媒体的支持依赖于 JSR 135, 也就是标准 J2ME 平台的 MMAPI BlackBerry 手机上录制视频也依靠 MMAPI, 支持 3gpp 视频格式, 支持的视频编码包括 MPEG-4, H263, H264, 音频编码包括 AAC, PCM, AMR 具体的视频音频编码支持依黑莓机型而定 BlackBerry 视屏录制编程包括以下几部分 : 1. 获取 / 选定手机对视频格式 / 编码的支持 2. 录制 / 存储视频 3. 回放已录制的视频获取 / 选定视频格式 / 编码通过系统提供的 API 可以获得该机型视频支持的所有视频规格 : String encodingsstring = System.getProperty("video.encodings"); encodingsstring 包含了全部能够支持的视频规格, 但它是一个 String, 还不能够直接使用, 需要进一步解析以下代码解析视频规格, 并返回规格列表 : * 获取黑莓手机所支持的视屏规格列表 public static String[] getvideoencodings() // 获取黑莓手机设备支持的视频格式 / 编码 String encodingsstring = System.getProperty("video.encodings"); // 如果没有支持的视频编码, 返回空 if( encodingsstring == null ) return null; // 解析出视频规格 Vector encodings = new Vector(); int start = 0; int space = encodingsstring.indexof(' '); 2

3 while( space!= -1 ) encodings.addelement(encodingsstring.substring(start, space)); start = space + 1; space = encodingsstring.indexof(' ', start); encodings.addelement(encodingsstring.substring(start, encodingsstring.length())); String[] encodingarray = new String[encodings.size()]; encodings.copyinto(encodingarray); return encodingarray; 解析后的视频规格范例如下所示 : encoding=video/3gpp&mode=standard encoding=video/3gpp&mode=mms encoding=video/3gpp&width=480&height=360&video_codec=mpeg-4&audio_codec=amr encoding=video/3gpp&width=176&height=144&video_codec=h263&audio_codec=amr encoding=video/3gpp&width=480&height=360&video_codec=h263&audio_codec=aac encoding=video/3gpp&width=480&height=360&video_codec=h264&audio_codec=aac encoding 字段表示视频格式 mode 表示播放模式, 模式会自动设置屏幕尺寸和编码 width 表示屏幕宽度 height 表示屏幕高度 video_codec 表示视频编码 audio_codec 表示音频编码视频规格如图所示 : 3

4 4

5 录制存储视频录制视频主要用到 Player,VideoControl,RecordControl,ByteArrayOutputStream 使用 Player 打开摄像头,VideoControl 将捕捉的视频显示到屏幕上,RecordControl 控制录制过程, ByteArrayOutputStream 作为视频录制的缓存以下三段代码范例分别为配置 / 启动摄像头, 开始录制, 和保存已录制的视频 * 构造一个屏幕显示和录制摄像头录制的视频 public VideoRecordingScreen(String encoding, String filepath) try // 开始捕捉视频 // encoding 是上一部分提到的视频规格 _player = javax.microedition.media.manager.createplayer("capture://video?" + encoding); _player.start(); _videocontrol = (VideoControl) _player.getcontrol("videocontrol"); _recordcontrol = (RecordControl) _player.getcontrol("recordcontrol"); // 将捕捉的视频显示在 Field 控件上 Field videofield = (Field) _videocontrol.initdisplaymode(videocontrol.use_gui_primitive, "net.rim.device.api.ui.field"); try // 视频尺寸为全屏 _videocontrol.setdisplaysize( Display.getWidth(), Display.getHeight() ); catch( MediaException me ) add(videofield); // 视频缓存, 捕捉到的视频将写入缓存 _outstream = new ByteArrayOutputStream(); _videofile = filepath; startrecord(); 5

6 catch( Exception e ) // Dispose of the player if it was created if( _player!= null ) _player.close(); _player = null; deleteall(); removeallmenuitems(); VideoRecordingDemo.errorDialog(e.toString()); 以上代码配置并启动摄像头 * 开始录制视频 private void startrecord() try if(!_pendingcommit ) // 重置缓存 _outstream.reset(); // 将缓存作为录制缓存 _recordcontrol.setrecordstream(_outstream); _pendingcommit = true; _committed = false; // 开始录制 _recordcontrol.startrecord(); _recording = true; 6

7 catch( Exception e) VideoRecordingDemo.errorDialog(e.toString()); 以上代码开始录制视频 * 保存录像 private void commitrecording() try // 这是最关键的一步, 保存录制的视频 _recordcontrol.commit(); // 重置参数 _pendingcommit = false; _committed = true; _recording = false; // 获取视频数据流 byte[] data = _outstream.tobytearray(); // 以文件的形式保存视频 FileConnection fconn = (FileConnection) Connector.open(_videoFile); if (fconn.exists()) fconn.delete(); fconn.create(); OutputStream os = fconn.openoutputstream(); os.write(data); os.flush(); os.close(); fconn.close(); 7

8 Dialog.alert("Committed"); catch( Exception e ) VideoRecordingDemo.errorDialog("RecordControl#commit() threw " + e.tostring()); 以上代码保存 / 存储视频回放已录制的视频前一步录制的视频以文件的形式保存在手机目录中, 回放视频需要文件路径, 载入文件, 使用 Player 在 Field 上进行播放代码如下 : * 构造视频回放屏幕, 按指定路径装载视频文件 Public VideoPlaybackScreen(String file) boolean notempty; // 检测给定路径是否有媒体文件 try FileConnection fconn = (FileConnection) Connector.open(file); notempty = fconn.exists() && fconn.filesize() > 0; fconn.close(); catch( IOException e ) Dialog.alert("Exception while accessing the video filesize:\n\n" + e); notempty = false; 8

9 // 如有媒体文件并有内容, 初始化界面进行播放 if( notempty ) try // 创建 Video Player _videoplayer = javax.microedition.media.manager.createplayer(file); initscreen(); catch( Exception e ) Dialog.alert("Exception while initializing the playback video player\n\n" + e); else add(new LabelField("The video file you are trying to play is empty")); 使用给定的路径创建 _videoplayer private void initscreen() throws Exception _videoplayer.realize(); // 注册媒体播放时间响应 _videoplayer.addplayerlistener(new PlayerListener() public void playerupdate(player player, String event, Object eventdata) // 定义媒体文件播放完毕时的响应 if( event == PlayerListener.END_OF_MEDIA ) UiApplication.getUiApplication().invokeLater(new Runnable() public void run() Dialog.alert("Finished playing"); close(); ); ); 9

10 // 获取 VideoControl 来获得播放视频的 Field _videocontrol = (VideoControl)_videoPlayer.getControl("VideoControl"); Field vfield = (Field) _videocontrol.initdisplaymode(videocontrol.use_gui_primitive, "net.rim.device.api.ui.field"); add(vfield); // 获取 VolumeControl 来指定声音大小 VolumeControl vol = (VolumeControl) _videoplayer.getcontrol("volumecontrol"); vol.setlevel(30); 初始化屏幕开始回放视频 _videoplayer.realize() 获取视频文件相关信息, 为播放做好准备之后 _videoplayer 注册了媒体播放事件侦听, 当媒体文件播放完毕时有事件响应从 _videoplayer 中获取 VideoControl,VideoControl 再返回视屏播放所占据的 Field, 添加这个 Field 到屏幕上来显示视屏 VolumeControl 可以定义声音大小, 也可以从 _videoplayer 中获取 10

11 完整代码类 VideoRecordingScreen.java package com.rim.samples.device.videorecordingdemo; import net.rim.device.api.ui.*; import net.rim.device.api.ui.container.*; import net.rim.device.api.ui.component.*; import net.rim.device.api.system.display; import javax.microedition.io.connector; import javax.microedition.io.file.fileconnection; import javax.microedition.media.*; import javax.microedition.media.control.*; import java.io.bytearrayoutputstream; import java.io.bytearrayinputstream; import java.io.outputstream; * This screen allows the user to record videos to a file or to a stream and * enables the user to open the VideoPlaybackScreen to play the recorded video. public class VideoRecordingScreen extends MainScreen private boolean _pendingcommit; private boolean _committed; private boolean _recording; private String _videofile; private Player _player; private VideoControl _videocontrol; private RecordControl _recordcontrol; private boolean _displayvisible; private ByteArrayOutputStream _outstream; public VideoRecordingScreen(String encoding, String filepath) 11

12 if (encoding == null) throw new NullPointerException("Video encoding can not be null"); if (filepath == null) throw new NullPointerException("File path can not be null"); try // 开始捕捉视频 // encoding 是视频规格 _player = javax.microedition.media.manager.createplayer("capture://video?" + encoding); _player.start(); _videocontrol = (VideoControl) _player.getcontrol("videocontrol"); _recordcontrol = (RecordControl) _player.getcontrol("recordcontrol"); // 将捕捉的视频显示在 Field 控件上 Field videofield = (Field) _videocontrol.initdisplaymode(videocontrol.use_gui_primitive, "net.rim.device.api.ui.field"); try // 视频尺寸为全屏 _videocontrol.setdisplaysize( Display.getWidth(), Display.getHeight() ); catch( MediaException me ) // setdisplaysize is not supported add(videofield); // 视频缓存, 捕捉到的视频将写入缓存 _outstream = new ByteArrayOutputStream(); _videofile = filepath; startrecord(); 12

13 catch( Exception e ) // Dispose of the player if it was created if( _player!= null ) _player.close(); _player = null; deleteall(); removeallmenuitems(); VideoRecordingDemo.errorDialog(e.toString()); * Commits the current recording private MenuItem _commit = new MenuItem("Commit recording", 0, 0) public void run() commitrecording(); ; * Plays the recording private MenuItem _playrecording = new MenuItem("Play recording", 0, 0) public void run() // Create the playback screen from the chosen video source VideoPlaybackScreen playbackscreen = new VideoPlaybackScreen(_videoFile); // Hide the video feed since we cannot display video from the camera // and video from a file at the same time. _videocontrol.setvisible(false); _displayvisible = false; ; UiApplication.getUiApplication().pushScreen(playbackScreen); 13

14 * Resets the recording private MenuItem _reset = new MenuItem("Reset recording", 0, 0) public void run() try _recordcontrol.reset(); catch( Exception e ) VideoRecordingDemo.errorDialog("RecordControl#reset threw " + e.tostring()); ; * Shows the video display private MenuItem _showdisplay = new MenuItem("Show display", 0, 0) public void run() _videocontrol.setvisible(true); _displayvisible = true; ; private MenuItem _hidedisplay = new MenuItem("Hide display", 0, 0) java.lang.runnable#run() public void run() _videocontrol.setvisible(false); _displayvisible = false; ; private MenuItem _startrecord = new MenuItem("Start recording", 0, 0) public void run() startrecord(); ; 14

15 private MenuItem _stoprecord = new MenuItem("Stop recording", 0, 0) public void run() stoprecord(); ; public boolean onclose() // Stop capturing video from the camera if( _player!= null ) _player.close(); return super.onclose(); protected boolean onsaveprompt() // Suppress the save prompt return true; protected void makemenu(menu menu, int instance) super.makemenu(menu, instance); if(_recording) menu.add(_stoprecord); else menu.add(_startrecord); if( _pendingcommit ) menu.add(_commit); menu.add(_reset); if(_committed) menu.add(_playrecording); if( _displayvisible) menu.add(_hidedisplay); else menu.add(_showdisplay); 15

16 protected boolean invokeaction(int action) switch(action) case ACTION_INVOKE: // Trackball click if(_recording) int response = Dialog.ask(Dialog.D_YES_NO, "Recording paused. recording?", Dialog.YES); if(response == Dialog.YES) this.commitrecording(); return true; // We've consumed the event return super.invokeaction(action); Commit protected void onvisibilitychange(boolean visible) if( visible && _player!= null ) _videocontrol.setvisible(true); _displayvisible = true; private void startrecord() try if(!_pendingcommit ) _outstream.reset(); // 将缓存作为录制缓存 _recordcontrol.setrecordstream(_outstream); _pendingcommit = true; _committed = false; // 开始录制 _recordcontrol.startrecord(); _recording = true; catch( Exception e ) VideoRecordingDemo.errorDialog(e.toString()); 16

17 private void stoprecord() try _recordcontrol.stoprecord(); _recording = false; catch( Exception e ) VideoRecordingDemo.errorDialog("RecordControl#stopRecord() threw " + e.tostring()); private void commitrecording() try _recordcontrol.commit(); _pendingcommit = false; _committed = true; _recording = false; // 获取视频数据流 byte[] data = _outstream.tobytearray(); // 以文件的形式保存视频 FileConnection fconn = (FileConnection) Connector.open(_videoFile); if (fconn.exists()) fconn.delete(); fconn.create(); OutputStream os = fconn.openoutputstream(); os.write(data); os.flush(); os.close(); fconn.close(); Dialog.alert("Committed"); catch( Exception e ) VideoRecordingDemo.errorDialog("RecordControl#commit() threw " + e.tostring()); 17

18 类 VideoRecordingSetupScreen.java package com.rim.samples.device.videorecordingdemo; import net.rim.device.api.ui.*; import net.rim.device.api.ui.container.*; import net.rim.device.api.ui.component.*; * A screen that allows a user to choose the encoding used to record * videos and the file system to record to. public final class VideoRecordingSetupScreen extends MainScreen implements FieldChangeListener private static String FILE_SYSTEM_URI_HEADER = "file:///"; private ObjectChoiceField _encodings; private ObjectChoiceField _filesystems; private ButtonField _launchrecorder; public VideoRecordingSetupScreen(String[] encodings) settitle("setup screen"); _encodings = new ObjectChoiceField("Encoding:", encodings, 0); add(_encodings); _filesystems = new ObjectChoiceField("File System", dir, 0); add(_filesystems); _launchrecorder = new ButtonField("Start recording", ButtonField.CONSUME_CLICK Field.FIELD_RIGHT); _launchrecorder.setchangelistener(this); add(_launchrecorder); public static final String[] dir = "store/", "SDCard/"; public static final String SD_CARD_PATH = "SDCard/BlackBerry/videos/mmapi_rimlet.3GP"; public static final String MEMORY_PATH = "store/home/user/videos/mmapi_rimlet.3gp"; public String videofilepath = SD_CARD_PATH; 18

19 public void fieldchanged(field field, int context) if( field == _launchrecorder ) String selectedencoding = (String) _encodings.getchoice(_encodings.getselectedindex()); String selectedfilesystem = (String) _filesystems.getchoice(_filesystems.getselectedindex()); String filepath = null; if(selectedfilesystem.equals("store/")) filepath = MEMORY_PATH; else if(selectedfilesystem.equals("sdcard/")) filepath = SD_CARD_PATH; UiApplication.getUiApplication().pushScreen( new VideoRecordingScreen(selectedEncoding, FILE_SYSTEM_URI_HEADER + filepath)); close(); protected boolean onsaveprompt() // Suppress the save dialog return true; 19

20 类 VideoPlaybackScreen.java package com.rim.samples.device.videorecordingdemo; import javax.microedition.media.player; import javax.microedition.media.playerlistener; import javax.microedition.media.control.videocontrol; import javax.microedition.media.control.volumecontrol; import java.io.ioexception; import java.io.inputstream; import javax.microedition.io.connector; import javax.microedition.io.file.fileconnection; import net.rim.device.api.ui.field; import net.rim.device.api.ui.uiapplication; import net.rim.device.api.ui.component.dialog; import net.rim.device.api.ui.component.labelfield; import net.rim.device.api.ui.container.mainscreen; public class VideoPlaybackScreen extends MainScreen private Player _videoplayer; private VideoControl _videocontrol; public VideoPlaybackScreen(InputStream inputstream) if (inputstream == null) throw new NullPointerException("'inputStream' cannot be null"); try _videoplayer = javax.microedition.media.manager.createplayer(inputstream, "video/sbv"); initscreen(); catch( Exception e ) Dialog.alert("Exception while initializing the playback video player\n\n" + e); 20

21 * 构造视频回放屏幕, 按指定路径装载视频文件 public VideoPlaybackScreen(String file) boolean notempty; // 检测给定路径是否有媒体文件 try FileConnection fconn = (FileConnection) Connector.open(file); notempty = fconn.exists() && fconn.filesize() > 0; fconn.close(); catch( IOException e ) Dialog.alert("Exception while accessing the video filesize:\n\n" + e); notempty = false; // 如有媒体文件并有内容, 初始化界面进行播放 if( notempty ) try // 创建 Video Player _videoplayer = javax.microedition.media.manager.createplayer(file); initscreen(); catch( Exception e ) Dialog.alert("Exception while initializing the playback video player\n\n" + e); else add(new LabelField("The video file you are trying to play is empty")); 21

22 private void initscreen() throws Exception _videoplayer.realize(); // 注册媒体播放时间响应 _videoplayer.addplayerlistener(new PlayerListener() public void playerupdate(player player, String event, Object eventdata) // 定义媒体文件播放完毕时的响应 if( event == PlayerListener.END_OF_MEDIA ) UiApplication.getUiApplication().invokeLater(new Runnable() public void run() Dialog.alert("Finished playing"); close(); ); ); // 获取 VideoControl 来获得播放视频的 Field _videocontrol = (VideoControl) _videoplayer.getcontrol("videocontrol"); Field vfield = (Field) _videocontrol.initdisplaymode(videocontrol.use_gui_primitive, "net.rim.device.api.ui.field"); add(vfield); // 获取 VolumeControl 来指定声音大小 VolumeControl vol = (VolumeControl) _videoplayer.getcontrol("volumecontrol"); vol.setlevel(30); 22

23 net.rim.device.api.ui.field#onvisibilitychange(boolean) protected void onvisibilitychange(boolean visible) // If the screen becomes visible and the video player was created, then // start the playback. if( visible && _videoplayer!= null ) try _videoplayer.start(); catch( Exception e ) // If starting the video fails, terminate the playback Dialog.alert("Exception while starting the video\n\n" + e); close(); net.rim.device.api.ui.screen#onclose() public void close() // Close the video player if it was created if( _videoplayer!= null ) _videoplayer.close(); super.close(); 23

24 类 VideoRecordingDemo.java package com.rim.samples.device.videorecordingdemo; import java.util.vector; import net.rim.device.api.ui.*; import net.rim.device.api.ui.component.*; import net.rim.device.api.system.display; * This application demonstrates how to capture and record video using the * JSR 135 Multi Media API (MMAPI). Video can be recorded from the camera to * either a file or to an output stream. This sample also demonstrates how * to playback the recorded video using the Multi Media API. public class VideoRecordingDemo extends UiApplication * Creates a new VideoRecordingDemo object public VideoRecordingDemo() // Check if video recording is enabled on this device final String[] encodings = getvideoencodings(); if ( encodings!= null && encodings.length > 0 ) pushscreen(new VideoRecordingSetupScreen(encodings)); else UiApplication.getApplication().invokeLater(new Runnable() public void run() Dialog.alert("This device is not capable of recording video"); System.exit(0); ); 24

25 public static void errordialog(final String message) UiApplication.getUiApplication().invokeLater(new Runnable() public void run() Dialog.alert(message); ); public static void main(string[] args) new VideoRecordingDemo().enterEventDispatcher(); public static String[] getvideoencodings() // 获取黑莓手机设备支持的视频格式 / 编码 String encodingsstring = System.getProperty("video.encodings"); // 如果没有支持的视频编码, 返回空 if( encodingsstring == null ) return null; // 解析出视频规格 Vector encodings = new Vector(); int start = 0; int space = encodingsstring.indexof(' '); while( space!= -1 ) encodings.addelement(encodingsstring.substring(start, space)); start = space + 1; space = encodingsstring.indexof(' ', start); encodings.addelement(encodingsstring.substring(start, encodingsstring.length())); String[] encodingarray = new String[encodings.size()]; encodings.copyinto(encodingarray); return encodingarray; 25

JavaIO.PDF

JavaIO.PDF O u t p u t S t ream j a v a. i o. O u t p u t S t r e a m w r i t e () f l u s h () c l o s e () public abstract void write(int b) throws IOException public void write(byte[] data) throws IOException