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本文实验平台：Eclipse + Opencv 2.4.10 + MTK Android 4.4平板（这一直是我的Android实验平台）
可能各位看官，看到前面的文章会觉得很凌乱，一会儿这个平台，一会儿那个平台。
其实我的主要思路就是：opencv中的任何一个功能，首先在windows上验证成功，再到Ubuntu，然后到Android上验证！
在windows上，由于其系统通用性，各方面支持肯定更好，所以我一定能验证成功，然后我再去Android上面做这些功能。这样前面的经验可以给我做参考，在Android上调试时可以敏锐滴知道问题出在哪里，并且这个过程下来三个平台都熟悉了，对于以后我的应用程序跨平台移植也是有帮助的！
回顾这段时间的工作，主要是三个阶段：
1. 在各个平台能够正常调用opencv的函数。例如yanzi_OpenCV4Android app的JNI里面有个灰度处理的函数Java_luo_uvc_jni_ImageProc_grayProc，就只是为了验证opencv可以调用。
2. 在各个平台能够正常获取图像，实现实时预览。这个阶段前面在windows、Ubuntu和Android基本都实现了，只是效果有差别而已。
3. 对2中的函数调用升级——在各个平台使用opencv2的C++类实现预览和录像。实际上opencv2的C++类只是对opencv1的C函数做了一次封装，但是看起来代码更干净简洁，也更方便和MAT结合。windows和Ubuntu已经验证完了，可以参考前面系列文章。
接下来我们验证VideoCapture和VideoWriter在Android上的使用！
把文章《我的Opencv4Android添加V4L2支持的移植记录(2)》中的例程yanzi_OpenCV4Android拷贝过来做如下修改
yanzi_OpenCV4Android6
ImageProc.cpp
#include "ImageProc.h"
#include "cv.h"
#include "highgui.h"
#include "opencv2/core/core.hpp"
#include "opencv2/highgui/highgui.hpp"
#include <string>
#include <vector>
using namespace cv;
using namespace std;
#ifdef __cplusplus
extern "C"
{
#pragma message("------------------------ ImageProc.cpp")
#endif
#define NAMELEN (64)
Mat frame;
VideoCapture capture;
char *prefix = NULL;
char fileName[NAMELEN] = {0};
VideoWriter writer;
int id;
JNIEXPORT jintArray JNICALL Java_luo_uvc_jni_ImageProc_grayProc(JNIEnv* env,
jclass obj, jintArray buf, jint w, jint h)
{
jint *cbuf;
cbuf = env->GetIntArrayElements(buf, false);
if (cbuf == NULL)
{
return 0;
}
Mat imgData(h, w, CV_8UC4, (unsigned char*) cbuf);
uchar* ptr = imgData.ptr(0);
for (int i = 0; i < w * h; i++)
{
//计算公式：Y(亮度) = 0.299*R + 0.587*G + 0.114*B
//对于一个int四字节，其彩色值存储方式为：BGRA
int grayScale = (int) (ptr[4 * i + 2] * 0.299 + ptr[4 * i + 1] * 0.587
+ ptr[4 * i + 0] * 0.114);
ptr[4 * i + 1] = grayScale;
ptr[4 * i + 2] = grayScale;
ptr[4 * i + 0] = grayScale;
}
int size = w * h;
jintArray result = env->NewIntArray(size);
env->SetIntArrayRegion(result, 0, size, cbuf);
env->ReleaseIntArrayElements(buf, cbuf, 0);
return result;
}
JNIEXPORT jint JNICALL Java_luo_uvc_jni_ImageProc_connectCamera(JNIEnv* env,
jclass obj, jint device)
{
id = device;
if (capture.isOpened())
{
LOGE("camera is already opened!");
return -2;
}
else
{
//打开一个默认的摄像头
capture.open(-1);
if (capture.isOpened())
{
LOGE("camera open success!");
return 0;
}
}
// LOGI("usb camera Java_luo_uvc_jni_ImageProc_connectCamera end ....\n");
return -1;
}
JNIEXPORT jint JNICALL Java_luo_uvc_jni_ImageProc_releaseCamera(JNIEnv* env,
jclass obj)
{
// LOGI("usb camera Java_luo_uvc_jni_ImageProc_releaseCamera start ....\n");
if (capture.isOpened())
{
capture.release();
LOGE("camera release success!");
return 0;
}
// LOGI("usb camera Java_luo_uvc_jni_ImageProc_releaseCamera end ....\n");
return -1;
}
struct FrameInfoClass
{
jfieldID width;
jfieldID heigth;
jfieldID imageSize;
jfieldID pixels;
};
JNIEXPORT jobject JNICALL Java_luo_uvc_jni_ImageProc_getFrame(JNIEnv* _env,
jclass obj)
{
// LOGI("------------Java_luo_uvc_jni_ImageProc_getFrame\n");
if (capture.isOpened())
{
LOGI("------------start capture frame\n");
//取图片帧
capture >> frame;
if (frame.empty())
{
LOGE("capture frame empty!");
return NULL;
}
//将图片写入视频文件
if(writer.isOpened())
{
//录制视频用的frame不需要转格式
writer.write(frame);
}
struct FrameInfoClass frameInfoClass;
//内部类用$
//luo/uvc/jni/ImageProc$FrameInfo
jclass class2 = _env->FindClass("luo/uvc/jni/ImageProc$FrameInfo");
frameInfoClass.width = _env->GetFieldID(class2, "mWidth", "I");
frameInfoClass.heigth = _env->GetFieldID(class2, "mHeight", "I");
frameInfoClass.imageSize = _env->GetFieldID(class2, "mImageSize", "I");
frameInfoClass.pixels = _env->GetFieldID(class2, "mPixels", "[I");
//
jobject joFrame = _env->AllocObject(class2);
LOGI("frame->cols = %d\n", frame.cols);
LOGI("frame->rows = %d\n", frame.rows);
// LOGI("frame->imageSize = %d\n", frame->imageSize);
_env->SetIntField(joFrame, frameInfoClass.width, frame.cols);
_env->SetIntField(joFrame, frameInfoClass.heigth, frame.rows);
// _env->SetIntField(joFrame, frameInfoClass.imageSize, frame->imageSize);
int size = frame.cols * frame.rows;
//创建一个新的java数组(jarray)，但是jarray不是C数组类型，不能直接访问jarray
jintArray jiArr = _env->NewIntArray(size);
jint *ji;
#if 1 //可用
//RGB --> ARGB8888
Mat frameARGB;
cvtColor(frame, frameARGB, CV_RGB2RGBA);
//JNI支持一系列的Get/Release<Type>ArrayElement 函数，允许本地代码获取一个指向基本C类型数组的元素的指针。
ji = _env->GetIntArrayElements(jiArr, 0);
memcpy((jbyte *) ji, frameARGB.data, 4 * size);
_env->ReleaseIntArrayElements(jiArr, ji, 0); //可加，可不加
_env->SetObjectField(joFrame, frameInfoClass.pixels, jiArr);
#else //可用
//可以使用GetIntArrayRegion函数来把一个 int数组中的所有元素复制到一个C缓冲区中
//SetIntArrayRegion则是逆过程
_env->SetIntArrayRegion(jiArr, 0, 2, abc);
_env->SetObjectField(joFrame, company_class.money, jiArr);
#endif
// LOGI("Java_luo_uvc_jni_ImageProc_getFrame end\n");
return joFrame;
}
// LOGI("=================Java_luo_uvc_jni_ImageProc_getFrame failed\n");
return 0;
}
JNIEXPORT jint JNICALL Java_luo_uvc_jni_ImageProc_startRecord
(JNIEnv *env, jclass, jstring jstr)
{
if(writer.isOpened() == false)
{
prefix = jstringToChar(env, jstr);
memset(fileName, 0, NAMELEN);
sprintf(fileName, "/storage/sdcard0/Movies/%s.avi", prefix);
LOGI("fileName: %s", fileName);
FREE(prefix);
writer.open(fileName, CV_FOURCC('F', 'L', 'V', '1')/*有效*/, 30, cv::Size(640, 480),true);
// writer.open(fileName, CV_FOURCC('M', 'J', 'P', 'G')/*有效*/, 30, cv::Size(640, 480),true);
// writer.open(fileName, CV_FOURCC('D', 'I', 'V', 'X')/*有效*/, 30, cv::Size(640, 480),true);
// writer.open(fileName, CV_FOURCC('X', 'V', 'I', 'D')/*有效*/, 30, cv::Size(640, 480),true);
if(writer.isOpened())
{
LOGE("writer open successful!");
return 0;
}
else
{
LOGE("writer open failed!");
return -2;
}
}
else
{
//实际上已经在录像
return -1;
}
}
JNIEXPORT jint JNICALL Java_luo_uvc_jni_ImageProc_stopRecord
(JNIEnv *, jclass)
{
if (writer.isOpened())
{
//如果正在录像，则停止录像
writer.release();
LOGI("%s end record!", fileName);
return 0;
}
return -1;
}
JNIEXPORT jint JNICALL Java_luo_uvc_jni_ImageProc_getWidth(JNIEnv* env,
jclass obj)
{
return 0;
}
JNIEXPORT jint JNICALL Java_luo_uvc_jni_ImageProc_getHeight(JNIEnv* env,
jclass obj)
{
return 0;
}
//jstring to char*
char* jstringToChar(JNIEnv* env, jstring jstr)
{
char* rtn = NULL;
jclass clsstring = env->FindClass("java/lang/String");
jstring strencode = env->NewStringUTF("utf-8");
jmethodID mid = env->GetMethodID(clsstring, "getBytes", "(Ljava/lang/String;)[B");
jbyteArray barr= (jbyteArray)env->CallObjectMethod(jstr, mid, strencode);
jsize alen = env->GetArrayLength(barr);
jbyte* ba = env->GetByteArrayElements(barr, JNI_FALSE);
if (alen > 0)
{
rtn = (char*)calloc(1, alen + 1);
memcpy(rtn, ba, alen);
rtn[alen] = 0;
}
env->ReleaseByteArrayElements(barr, ba, 0);
return rtn;
}
#ifdef __cplusplus
}
#endif
/* end of extern */
package luo.uvc.jni;
import java.text.SimpleDateFormat;
import java.util.Date;
import luo.uvc.jni.ImageProc.FrameInfo;
import android.R.bool;
import android.R.string;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.Bitmap.Config;
import android.util.AttributeSet;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.widget.Toast;
public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback, Runnable
{
public static final String TAG = "UVCCameraPreview";
protected Context context;
private SurfaceHolder holder;
Thread mainLoop = null;
public static final int SET_PREVIEW_TEXT = 0;
public static final int SET_RECORD_TEXT = 1;
private boolean mIsOpened = false;
private boolean mIsRecording = false;
private boolean shouldStop = false;
public callback textCallback;
// The following variables are used to draw camera images.
private int winWidth = 0;
private int winHeight = 0;
private Rect rect;
private int dw, dh;
private float rate;
public CameraPreview(Context context)
{
super(context);
// TODO Auto-generated constructor stub
this.context = context;
Log.d(TAG, "CameraPreview constructed");
setFocusable(true);
holder = getHolder();
holder.addCallback(this);
holder.setType(SurfaceHolder.SURFACE_TYPE_NORMAL);
}
//注意：使用findViewById获取CameraPreview，会调用这个构造函数
public CameraPreview(Context context, AttributeSet attrs)
{
super(context, attrs);
this.context = context;
Log.d(TAG, "CameraPreview constructed");
setFocusable(true);
holder = getHolder();
holder.addCallback(this);
holder.setType(SurfaceHolder.SURFACE_TYPE_NORMAL);
}
public void initPreview()
{
int index = -1;
if (mIsOpened == false)
{
if (0 == ImageProc.connectCamera(index))
{
Log.i(TAG, "open uvc success!!!");
mIsOpened = true;
textCallback.setViewText(SET_PREVIEW_TEXT, "关闭");
if (null != mainLoop)
{
shouldStop = false;
Log.i(TAG, "preview mainloop starting...");
mainLoop.start();
}
Toast.makeText(context.getApplicationContext(), "成功打开摄像头", Toast.LENGTH_SHORT).show();
} else
{
Log.i(TAG, "open uvc fail!!!");
mIsOpened = false;
Toast.makeText(context.getApplicationContext(), "摄像头打开失败", Toast.LENGTH_SHORT).show();
}
} else
{
uninitPreview();
}
}
public void uninitPreview()
{
//结束录制
uninitRecord();
//停止预览线程
if (null != mainLoop)
{
Log.i(TAG, mainLoop.isAlive() ? "mainloop is alive!" : "mainloop is not alive!");
if (mainLoop.isAlive())
{
shouldStop = true;
while (shouldStop)
{
try
{
Thread.sleep(100); // wait for thread stopping
} catch (Exception e)
{
}
}
}
}
//关闭camera
if (mIsOpened)
{
mIsOpened = false;
ImageProc.releaseCamera();
textCallback.setViewText(SET_PREVIEW_TEXT, "打开");
Log.i(TAG, "release camera...");
}
}
public void initRecord()
{
if(mIsOpened)
{
if(mIsRecording == false)
{
Log.i(TAG, "init camera record!");
Date date = new Date();
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyyMMddHHmmss");
String dateString = simpleDateFormat.format(date);
if(null == dateString)
{
dateString = "luoyouren";
}
Log.i(TAG, dateString);
if(0 == ImageProc.startRecord(dateString))
{
mIsRecording = true;
textCallback.setViewText(SET_RECORD_TEXT, "停止");
Toast.makeText(context.getApplicationContext(), "开始录制...", Toast.LENGTH_SHORT).show();
}
else
{
mIsRecording = false;
Log.e(TAG, "init camera record failed!");
Toast.makeText(context.getApplicationContext(), "录制启动失败！", Toast.LENGTH_SHORT).show();
}
return;
}
else
{
uninitRecord();
return;
}
}
else
{
Log.e(TAG, "camera has not been opened!");
return;
}
}
public void uninitRecord()
{
if(mIsRecording)
{
Log.i(TAG, "camera is already recording! So we stop it.");
ImageProc.stopRecord();
mIsRecording = false;
textCallback.setViewText(SET_RECORD_TEXT, "录制");
return;
}
}
public boolean isOpen()
{
return mIsOpened;
}
public boolean isRecording()
{
return mIsRecording;
}
@Override
public void run()
{
// TODO Auto-generated method stub
while (true && mIsOpened)
{
// get camera frame
FrameInfo frame = ImageProc.getFrame();
if (null == frame)
{
continue;
}
int w = frame.getWidth();
int h = frame.getHeigth();
Log.i(TAG, "frame.width = " + w + " frame.height = " + h);
// 根据图像大小更新显示区域大小
// 一般来说图像大小不会变化: 640x480
updateRect(w, h);
Bitmap resultImg = Bitmap.createBitmap(w, h, Config.ARGB_8888);
resultImg.setPixels(frame.getPixels(), 0, w, 0, 0, w, h);
// 刷surfaceview显示
Canvas canvas = getHolder().lockCanvas();
if (canvas != null)
{
// draw camera bmp on canvas
canvas.drawBitmap(resultImg, null, rect, null);
getHolder().unlockCanvasAndPost(canvas);
}
if (shouldStop)
{
shouldStop = false;
Log.i(TAG, "mainloop will stop!");
break;
}
}
Log.i(TAG, "mainloop break while!");
}
public void updateRect(int frame_w, int frame_h)
{
// obtaining display area to draw a large image
if (winWidth == 0)
{
winWidth = this.getWidth();
winHeight = this.getHeight();
if (winWidth * 3 / 4 <= winHeight)
{
dw = 0;
dh = (winHeight - winWidth * 3 / 4) / 2;
rate = ((float) winWidth) / frame_w;
rect = new Rect(dw, dh, dw + winWidth - 1, dh + winWidth * 3 / 4 - 1);
} else
{
dw = (winWidth - winHeight * 4 / 3) / 2;
dh = 0;
rate = ((float) winHeight) / frame_h;
rect = new Rect(dw, dh, dw + winHeight * 4 / 3 - 1, dh + winHeight - 1);
}
}
}
@Override
public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3)
{
// TODO Auto-generated method stub
}
@Override
public void surfaceCreated(SurfaceHolder arg0)
{
// TODO Auto-generated method stub
mainLoop = new Thread(this);
updateRect(512, 512);
// 将lena图像加载程序中并进行显示
Bitmap resultImg = BitmapFactory.decodeResource(getResources(), R.drawable.lena);
// 刷surfaceview显示
Canvas canvas = getHolder().lockCanvas();
if (canvas != null)
{
// draw camera bmp on canvas
canvas.drawBitmap(resultImg, null, rect, null);
getHolder().unlockCanvasAndPost(canvas);
}
}
@Override
public void surfaceDestroyed(SurfaceHolder arg0)
{
// TODO Auto-generated method stub
}
}
编译、安装、运行后，Camera实时预览正常，和《我的Opencv4Android添加V4L2支持的移植记录(2)》中一样，但是录像失败！
我们可以来看看opencv里面，对于各个平台VideoWriter功能的分发情况
/**
* Videowriter dispatching method: it tries to find the first
* API that can write a given stream.
*/
CV_IMPL CvVideoWriter* cvCreateVideoWriter( const char* filename, int fourcc,
double fps, CvSize frameSize, int is_color )
{
//CV_FUNCNAME( "cvCreateVideoWriter" );
CvVideoWriter *result = 0;
#pragma message("------------------------ cvCreateVideoWriter")
if(!fourcc || !fps)
result = cvCreateVideoWriter_Images(filename);
#ifdef HAVE_FFMPEG
#pragma message("------------------------ HAVE_FFMPEG")
if(!result)
result = cvCreateVideoWriter_FFMPEG_proxy (filename, fourcc, fps, frameSize, is_color);
#endif
#ifdef HAVE_VFW
#pragma message("------------------------ HAVE_VFW")
if(!result)
result = cvCreateVideoWriter_VFW(filename, fourcc, fps, frameSize, is_color);
#endif
#ifdef HAVE_MSMF
#pragma message("------------------------ HAVE_MSMF")
if (!result)
result = cvCreateVideoWriter_MSMF(filename, fourcc, fps, frameSize, is_color);
#endif
/* #ifdef HAVE_XINE
if(!result)
result = cvCreateVideoWriter_XINE(filename, fourcc, fps, frameSize, is_color);
#endif
*/
#ifdef HAVE_AVFOUNDATION
#pragma message("------------------------ HAVE_AVFOUNDATION")
if (! result)
result = cvCreateVideoWriter_AVFoundation(filename, fourcc, fps, frameSize, is_color);
#endif
#if defined(HAVE_QUICKTIME) || defined(HAVE_QTKIT)
#pragma message("------- defined(HAVE_QUICKTIME) || defined(HAVE_QTKIT)")
if(!result)
result = cvCreateVideoWriter_QT(filename, fourcc, fps, frameSize, is_color);
#endif
#ifdef HAVE_GSTREAMER
#pragma message("------------------------ HAVE_GSTREAMER")
if (! result)
result = cvCreateVideoWriter_GStreamer(filename, fourcc, fps, frameSize, is_color);
#endif
#if !defined(HAVE_FFMPEG) && !defined(HAVE_VFW) && !defined(HAVE_MSMF) && !defined(HAVE_AVFOUNDATION) && !defined(HAVE_QUICKTIME) && !defined(HAVE_QTKIT) && !defined(HAVE_GSTREAMER)
// If none of the writers is used
// these statements suppress 'unused parameter' warnings.
(void)frameSize;
(void)is_color;
#endif
#pragma message("------------------------ cvCreateVideoWriter_Images")
if(!result)
result = cvCreateVideoWriter_Images(filename);
return result;
}
enum
{
CV_CAP_ANY =0, // autodetect
CV_CAP_MIL =100, // MIL proprietary drivers
CV_CAP_VFW =200, // platform native
CV_CAP_V4L =200,
CV_CAP_V4L2 =200,
CV_CAP_FIREWARE =300, // IEEE 1394 drivers
CV_CAP_FIREWIRE =300,
CV_CAP_IEEE1394 =300,
CV_CAP_DC1394 =300,
CV_CAP_CMU1394 =300,
CV_CAP_STEREO =400, // TYZX proprietary drivers
CV_CAP_TYZX =400,
CV_TYZX_LEFT =400,
CV_TYZX_RIGHT =401,
CV_TYZX_COLOR =402,
CV_TYZX_Z =403,
CV_CAP_QT =500, // QuickTime
CV_CAP_UNICAP =600, // Unicap drivers
CV_CAP_DSHOW =700, // DirectShow (via videoInput)
CV_CAP_MSMF =1400, // Microsoft Media Foundation (via videoInput)
CV_CAP_PVAPI =800, // PvAPI, Prosilica GigE SDK
CV_CAP_OPENNI =900, // OpenNI (for Kinect)
CV_CAP_OPENNI_ASUS =910, // OpenNI (for Asus Xtion)
CV_CAP_ANDROID =1000, // Android
CV_CAP_ANDROID_BACK =CV_CAP_ANDROID+99, // Android back camera
CV_CAP_ANDROID_FRONT =CV_CAP_ANDROID+98, // Android front camera
CV_CAP_XIAPI =1100, // XIMEA Camera API
CV_CAP_AVFOUNDATION = 1200, // AVFoundation framework for iOS (OS X Lion will have the same API)
CV_CAP_GIGANETIX = 1300, // Smartek Giganetix GigEVisionSDK
CV_CAP_INTELPERC = 1500 // Intel Perceptual Computing SDK
};
看看之前的Cmake的结果对比就知道：
Opencv在我增加V4L2后，也支持NativeCamera和V4L2两种Video I/O，而Ubuntu有FFMPEG的支持（不懂FFMPEG的去问度娘）。并且在cvCreateVideoWriter函数中也没有对NativeCamera的支持，所以我的APP录像失败。
所以如果要让yanzi_OpenCV4Android 能够录像，就要添加FFMPEG的支持！！！！
PS：
昨天我一直在纠结一个问题，VFW和DirectShow都是微软视频处理框架，DirectShow是VFW的升级版。但是在Opencv中，
cvCreateCameraCapture 读摄像头
cvCreateFileCapture 读视频文件
cvCreateVideoWriter 写视频文件
和摄像头相关的cvCreateCameraCapture 里面对DirectShow和VFW都有支持，但是和文件相关的后面两个函数只对VFW有支持。
我猜测大概是DirectShow不善于处理视频文件。
我的Opencv4Android添加V4L2支持的移植记录(3)
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原文地址：http://blog.csdn.net/luoyouren/article/details/51895475
