如何在Android中捕获视频？
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How to capture video in Android?
提问by Niko Gamulin
I would like to create a video recorder and so far haven't figured out how to set parameters in order to successfully go through MediaRecorder.prepare() method.
我想创建一个录像机，到目前为止还没有弄清楚如何设置参数以成功通过 MediaRecorder.prepare() 方法。
Executing the following method
执行以下方法
public void start() throws IOException{
String state = android.os.Environment.getExternalStorageState();
if(!state.equals(Environment.MEDIA_MOUNTED))
{
throw new IOException("SD card is not mounted. It is " + state + ".");
}
File directory = new File(path).getParentFile();
if(!directory.exists() && !directory.mkdirs())
{
throw new IOException("Path to file could not be created.");
}
recorder.setVideoSource(MediaRecorder.VideoSource.CAMERA);
recorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
recorder.setVideoEncoder(MediaRecorder.VideoEncoder.H263);
recorder.setVideoFrameRate(15);
recorder.setVideoSize(176, 144);
recorder.setOutputFile(path);
recorder.prepare();
recorder.start();
this.state = VideoRecorderState.STATE_RECORDING;
}
it throws an exception on line recorder.prepare().
它在线抛出异常 recorder.prepare().
How to set parameters in order to be able to capture video?
如何设置参数才能捕获视频？
回答by BeMeCollective
Here is a snippet that works:
这是一个有效的片段：
m_recorder = new MediaRecorder();
m_recorder.setPreviewDisplay(m_BeMeSurface);
m_recorder.setAudioSource(MediaRecorder.AudioSource.MIC);
m_recorder.setVideoSource(MediaRecorder.VideoSource.DEFAULT);
m_recorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
m_recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
m_recorder.setVideoEncoder(MediaRecorder.VideoEncoder.MPEG_4_SP);
m_recorder.setMaxDuration((int) MAX_TIME);
m_recorder.setOnInfoListener(m_BeMeSelf);
m_recorder.setVideoSize(320, 240);
m_recorder.setVideoFrameRate(15);
m_recorder.setOutputFile(m_path);
m_recorder.prepare();
m_recorder.start();
THE most important thing is the surface. You don't have it, so without it it fails.
最重要的是表面。你没有它，所以没有它它就会失败。
Regards
问候
BeMeCollective
BeMeCollective
回答by Integrating Stuff
I am exactly answering this question in the following tutorial: http://integratingstuff.wordpress.com/2010/10/18/writing-code-that-captures-videos-on-android/
我在以下教程中完全回答了这个问题：http: //integratingstuff.wordpress.com/2010/10/18/writing-code-that-captures-videos-on-android/
The reason why your code is failing on prepare() is because you didn't set all the necessary properties. For example, you also need to set maxDuration.
您的代码在 prepare() 上失败的原因是您没有设置所有必要的属性。例如，您还需要设置 maxDuration。
回答by cesine
I had the same question. I was going from a background audio recording service, and hoping to create a background video recording service. You can't truly record background video, but you can make the video preview very small in your existing UI. I followed the tutorial: http://integratingstuff.wordpress.com/2010/10/18/writing-code-that-captures-videos-on-android/and the sample Camera Preview demo. But ultimately the sample code in http://www.apress.com/downloadable/download/sample/sample_id/39/was simple enough to tweek, but also complete enough to work with setCamera. I will post my solution here to save others time in their progression from toy examples, to a complex example with good quality background video recording (using front facing camera if necessary).
我有同样的问题。我打算从后台录音服务，并希望创建一个后台视频录制服务。您无法真正录制背景视频，但您可以在现有 UI 中将视频预览设置得非常小。我遵循了教程：http: //integratingstuff.wordpress.com/2010/10/18/writing-code-that-captures-videos-on-android/和示例相机预览演示。但最终http://www.apress.com/downloadable/download/sample/sample_id/39/ 中的示例代码足够简单，可以进行 tweek，但也足够完整，可以与 setCamera 一起使用。我将在这里发布我的解决方案，以节省其他人在从玩具示例到具有高质量背景视频录制的复杂示例（如有必要，使用前置摄像头）的过程中的时间。
This is the source for an Android video recorder with "no" preview (the preview is a 1x1 pixel which simulates an unobtrusive recording led), to record video without distracting users. To use your own UI, simply change the video_recorder.xml to your layout (be sure to keep the VideoView). It was tested on Android 2.2 and 3.0 devices.
这是具有“无”预览功能的 Android 视频录像机的来源（预览是一个 1x1 像素，模拟不显眼的录制 LED），以便在不分散用户注意力的情况下录制视频。要使用您自己的 UI，只需将 video_recorder.xml 更改为您的布局（确保保留 VideoView）。它在 Android 2.2 和 3.0 设备上进行了测试。
Suitable use cases:
合适的用例：
- eye gaze tracking library to let users use eyes as a mouse to navigate a web page
- use tablet camera(s) to replace video camera in lab/clinic experiments (psycholingusitics or speech pathology)
- 眼睛注视跟踪库，让用户使用眼睛作为鼠标来浏览网页
- 在实验室/临床实验（心理语言学或言语病理学）中使用平板相机代替摄像机
Layout xml:
布局xml：
<?xml version="1.0" encoding="utf-8"?>
<!-- This file is /res/layout/video_recorder.xml based on listing 9-6 in Pro Android 2 -->
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="fill_parent"
android:layout_height="fill_parent">
<RelativeLayout android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:gravity="center">
<VideoView android:id="@+id/videoView" android:layout_width="1px"
android:layout_height="1px" />
</RelativeLayout>
</LinearLayout>
Java class:
Java类：
import java.io.File;
import android.app.Activity;
import android.hardware.Camera;
import android.media.MediaRecorder;
import android.os.Bundle;
import android.util.Log;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.widget.Toast;
import android.widget.VideoView;
/**
* Android video recorder with "no" preview (the preview is a 1x1 pixel which
* simulates an unobtrusive recording led). Based on Pro Android 2 2010 (Hashimi
* et al) source code in Listing 9-6.
*
* Also demonstrates how to use the front-facing and back-facing cameras.
* A calling Intent can pass an Extra to use the front facing camera if available.
*
* Suitable use cases:
* A: eye gaze tracking library to let users use eyes as a mouse to navigate a web page
* B: use tablet camera(s) to replace video camera in lab experiments
* (psycholingusitics or other experiments)
*
* Video is recording is controlled in two ways:
* 1. Video starts and stops with the activity
* 2. Video starts and stops on any touch
*
* To control recording in other ways see the try blocks of the onTouchEvent
*
* To incorporate into project add these features and permissions to
* manifest.xml:
*
* <uses-feature android:name="android.hardware.camera"/>
* <uses-feature android:name="android.hardware.camera.autofocus"/>
*
* <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
* <uses-permission android:name="android.permission.CAMERA" />
* <uses-permission android:name="android.permission.RECORD_AUDIO" />
*
* Tested Date: October 2 2011 with manifest.xml
* <uses-sdk android:minSdkVersion="8" android:targetSdkVersion="11"/>
*/
public class VideoRecorderSubExperiment extends Activity implements
SurfaceHolder.Callback {
public static final String EXTRA_USE_FRONT_FACING_CAMERA ="frontcamera";
private static final String OUTPUT_FILE = "/sdcard/videooutput";
private static final String TAG = "RecordVideo";
private Boolean mRecording = false;
private Boolean mUseFrontFacingCamera = false;
private VideoView mVideoView = null;
private MediaRecorder mVideoRecorder = null;
private Camera mCamera;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.video_recorder);
mVideoView = (VideoView) this.findViewById(R.id.videoView);
//mUseFrontFacingCamera = getIntent().getExtras().getBoolean(
// EXTRA_USE_FRONT_FACING_CAMERA, true);
if(mUseFrontFacingCamera){
// If caller wants to use front facing camera, then make sure the device has one...
// Hard coded to only open front facing camera on Xoom (model MZ604)
// For more universal solution try:
// http://stackoverflow.com/questions/2779002/how-to-open-front-camera-on-android-platform
String deviceModel = android.os.Build.MODEL;
if (deviceModel.contains("MZ604")) {
mUseFrontFacingCamera = true;
} else {
Toast.makeText(
getApplicationContext(),
"The App isn't designed to use this Android's front facing camera.\n " +
"The device model is : " + deviceModel, Toast.LENGTH_LONG).show();
mUseFrontFacingCamera = false;
}
}
final SurfaceHolder holder = mVideoView.getHolder();
holder.addCallback(this);
holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}
public boolean onTouchEvent(MotionEvent event) {
// can use the xy of the touch to start and stop recording
float positionX = event.getX();
float positionY = event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
// Screen is pressed for the first time
break;
case MotionEvent.ACTION_MOVE:
// Screen is still pressed, float have been updated
break;
case MotionEvent.ACTION_UP:
// Screen is not touched anymore
if (mRecording) {
// To stop recording attach this try block to another event listener,
// button etc
try {
stopRecording();
} catch (Exception e) {
Log.e(TAG, e.toString());
e.printStackTrace();
}
} else {
// To begin recording attach this try block to another event listener,
// button etc
try {
beginRecording(mVideoView.getHolder());
} catch (Exception e) {
Log.e(TAG, e.toString());
e.printStackTrace();
}
}
break;
}
return super.onTouchEvent(event);
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
try {
beginRecording(holder);
} catch (Exception e) {
Log.e(TAG, e.toString());
e.printStackTrace();
}
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
Log.v(TAG, "Width x Height = " + width + "x" + height);
}
private void stopRecording() throws Exception {
mRecording = false;
if (mVideoRecorder != null) {
mVideoRecorder.stop();
mVideoRecorder.release();
mVideoRecorder = null;
}
if (mCamera != null) {
mCamera.reconnect();
mCamera.stopPreview();
mCamera.release();
mCamera = null;
}
}
@Override
protected void onDestroy() {
try {
stopRecording();
} catch (Exception e) {
Log.e(TAG, e.toString());
e.printStackTrace();
}
super.onDestroy();
}
/**
* Uses the surface defined in video_recorder.xml
* Tested using
* 2.2 (HTC Desire/Hero phone) -> Use all defaults works, records back facing camera with AMR_NB audio
* 3.0 (Motorola Xoom tablet) -> Use all defaults doesn't work, works with these specs, might work with others
*
* @param holder The surfaceholder from the videoview of the layout
* @throws Exception
*/
private void beginRecording(SurfaceHolder holder) throws Exception {
if (mVideoRecorder != null) {
mVideoRecorder.stop();
mVideoRecorder.release();
mVideoRecorder = null;
}
if (mCamera != null) {
mCamera.reconnect();
mCamera.stopPreview();
mCamera.release();
mCamera = null;
}
String uniqueOutFile = OUTPUT_FILE + System.currentTimeMillis() + ".3gp";
File outFile = new File(uniqueOutFile);
if (outFile.exists()) {
outFile.delete();
}
try {
if (mUseFrontFacingCamera) {
//hard coded assuming 1 is the front facing camera
mCamera = Camera.open(1);
} else {
mCamera = Camera.open();
}
// Camera setup is based on the API Camera Preview demo
mCamera.setPreviewDisplay(holder);
Camera.Parameters parameters = mCamera.getParameters();
parameters.setPreviewSize(640, 480);
mCamera.setParameters(parameters);
mCamera.startPreview();
mCamera.unlock();
mVideoRecorder = new MediaRecorder();
mVideoRecorder.setCamera(mCamera);
// Media recorder setup is based on Listing 9-6, Hashimi et all 2010
// values based on best practices and good quality,
// tested via upload to YouTube and played in QuickTime on Mac Snow Leopard
mVideoRecorder.setVideoSource(MediaRecorder.VideoSource.CAMERA);
mVideoRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
mVideoRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);// THREE_GPP
// is big-endian,
// storing and
// transferring
// the most
// significant
// bytes first.
// MPEG_4 as another option
mVideoRecorder.setVideoSize(640, 480);// YouTube recommended size: 320x240,
// OpenGazer eye tracker: 640x480
// YouTube HD: 1280x720
mVideoRecorder.setVideoFrameRate(20); //might be auto-determined due to lighting
mVideoRecorder.setVideoEncodingBitRate(3000000);// 3 megapixel, or the max of
// the camera
mVideoRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.H264);// MPEG_4_SP
// Simple Profile is
// for low bit
// rate and low
// resolution
// H264 is MPEG-4 Part 10
//is commonly referred to
// as H.264 or AVC
int sdk = android.os.Build.VERSION.SDK_INT;
// Gingerbread and up can have wide band ie 16,000 hz recordings
// (Okay quality for human voice)
if (sdk >= 10) {
mVideoRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_WB);
mVideoRecorder.setAudioSamplingRate(16000);
} else {
// Other devices only have narrow band, ie 8,000 hz
// (Same quality as a phone call, not really good quality for any purpose.
// For human voice 8,000 hz means /f/ and /th/ are indistinguishable)
mVideoRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
}
mVideoRecorder.setMaxDuration(30000); // limit to 30 seconds
mVideoRecorder.setPreviewDisplay(holder.getSurface());
mVideoRecorder.setOutputFile(uniqueOutFile);
mVideoRecorder.prepare();
mVideoRecorder.start();
mRecording = true;
} catch (Exception e) {
Log.e(TAG, e.toString());
e.printStackTrace();
}
}
}
回答by ajaxlex
Have you checked this out?
你检查过这个吗？
http://code.google.com/p/android/issues/detail?id=5050
http://code.google.com/p/android/issues/detail?id=5050
These guys suggest that it is a timing issue, and that the MediaRecorder state machine may require some delay (hardware dependent?) between states.
这些人认为这是一个时间问题，并且 MediaRecorder 状态机可能需要一些状态之间的延迟（取决于硬件？）。
It would be nice if there were callbacks for when each state was fully achieved - then we could just put prepare in that.
如果在每个状态完全实现时有回调，那就太好了——然后我们可以把准备放在里面。
回答by Josef Pfleger
This could be a permissions error. Do you have the android.permission.CAMERA permission set in your AndroidManifest file?
这可能是权限错误。您的 AndroidManifest 文件中是否设置了 android.permission.CAMERA 权限？
回答by Rafael Diego Nicoletti
In my case, copying and pasting the samples above didn't work. Then, viewing the methods in MediaRecorder, I found setPreviewDisplay. I called this method passing the surface used in Camera.setPreviewDisplay, the IOException in .prepare is gone and I was able to record video. Try yourself and post your results.
就我而言，复制和粘贴上面的示例不起作用。然后，查看MediaRecorder中的方法，发现setPreviewDisplay。我调用此方法传递 Camera.setPreviewDisplay 中使用的表面，.prepare 中的 IOException 消失了，我能够录制视频。尝试自己并发布您的结果。
