流媒体程序开发之:H264解码器移植到OPhone

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模拟器一样是模拟ARM指令的,不像Symbian模拟器一样执行的是本地代码,所以在模拟器上模拟出来的效率会比真实手机上的效率要低,之前这款解码器已经优化到在nokia 6600(相当低端的一款手机,CPU主频才120Hz)上做到在线播放。

假定前提
1)熟悉Java/C/C++语言;
2)熟悉Java的JNI技术;
3)有一定的跨手机平台移植经验;
4)有一套可供移植的源代码库,这里以H.264解码库为例,为了保护我们的知识版权,这里只能够公开头文件:

 

 

  1. #ifndef __H264DECODE_H__   
  2. #define __H264DECODE_H__   
  3.   
  4. #if defined(__SYMBIAN32__)  //S602rd/3rd/UIQ   
  5.     #include <e32base.h>   
  6.     #include <libc/stdio.h>   
  7.     #include <libc/stdlib.h>   
  8.     #include <libc/string.h>   
  9. #else                       //Windows/Mobile/MTK/OPhone   
  10.     #include <stdio.h>   
  11.     #include <stdlib.h>   
  12.     #include <string.h>   
  13. #endif   
  14.   
  15. class H264Decode   
  16. {   
  17. public:   
  18.     /***************************************************************************/  
  19.     /* 构造解码器                                                        */  
  20.     /* @return H264Decode解码器实例                                      */  
  21.     /***************************************************************************/  
  22.     static H264Decode *H264DecodeConstruct();   
  23.     /***************************************************************************/  
  24.     /* 解码一帧                                                     */  
  25.     /* @pInBuffer   指向H264的视频流                                      */  
  26.     /* @iInSize H264视频流的大小                                      */  
  27.     /* @pOutBuffer  解码后的视频视频                                        */  
  28.     /* @iOutSize    解码后的视频大小                                        */  
  29.     /* @return      已解码的H264视频流的尺寸                              */  
  30.     /***************************************************************************/  
  31.     int DecodeOneFrame(unsigned char *pInBuffer,unsigned int iInSize,unsigned char *pOutBuffer,unsigned int &iOutSize);   
  32.     ~H264Decode();   
  33. };   
  34. #endif  // __H264DECODE_H__  

 

      你不用熟悉Android平台,一切从零开始,因为在此之前,我也不熟悉

 

 

封装Java接口

        在“假定前提”中提到了要移植的函数,接下来会编写这些 函数的Java Native Interface。

 

 

  1. package ophone.streaming.video.h264;   
  2.   
  3. import java.nio.ByteBuffer;   
  4.   
  5. public class H264decode {   
  6.        
  7. //H264解码库指针,因为Java没有指针一说,所以这里用一个32位的数来存放指针的值   
  8.     private long H264decode = 0;   
  9.        
  10.     static{      
  11.         System.loadLibrary("H264Decode");   
  12.     }   
  13.   
  14.     public H264decode() {   
  15.         this.H264decode = Initialize();   
  16.     }   
  17.        
  18.     public void Cleanup() {   
  19.         Destroy(H264decode);   
  20.     }   
  21.        
  22.     public int DecodeOneFrame(ByteBuffer pInBuffer,ByteBuffer pOutBuffer) {   
  23.         return DecodeOneFrame(H264decode, pInBuffer, pOutBuffer);   
  24.     }   
  25.   
  26.     private native static int DecodeOneFrame(long H264decode,ByteBuffer pInBuffer,ByteBuffer pOutBuffer);   
  27.     private native static long Initialize();   
  28.     private native static void Destroy(long H264decode);   
  29. }  

 

 

  1. #include <jni.h>   
  2.   
  3. #ifndef _Included_ophone_streaming_video_h264_H264decode   
  4. #define _Included_ophone_streaming_video_h264_H264decode   
  5. #ifdef __cplusplus   
  6. extern "C" {   
  7. #endif   
  8.   
  9. JNIEXPORT jint JNICALL Java_ophone_streaming_video_h264_H264decode_DecodeOneFrame   
  10.   (JNIEnv *, jclass, jlong, jobject, jobject);   
  11.   
  12. JNIEXPORT jlong JNICALL Java_ophone_streaming_video_h264_H264decode_Initialize   
  13.   (JNIEnv *, jclass);   
  14.   
  15. JNIEXPORT void JNICALL Java_ophone_streaming_video_h264_H264decode_Destroy   
  16.   (JNIEnv *, jclass, jlong);   
  17.   
  18. #ifdef __cplusplus   
  19. }   
  20. #endif   
  21. #endif 

  之前已经生成了JNI头文件,接下来只需要实现这个头文件的几个导出函数,这里以H264解码器的实现为例:

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  1. #include "ophone_streaming_video_h264_H264decode.h"  
  2. #include "H264Decode.h"  
  3.   
  4. JNIEXPORT jint JNICALL Java_ophone_streaming_video_h264_H264decode_DecodeOneFrame   
  5.   (JNIEnv * env, jclass obj, jlong decode, jobject pInBuffer, jobject pOutBuffer) {   
  6.   
  7.     H264Decode *pDecode = (H264Decode *)decode;   
  8.     unsigned char *In = NULL;unsigned char *Out = NULL;   
  9.     unsigned int InPosition = 0;unsigned int InRemaining = 0;unsigned int InSize = 0;   
  10.     unsigned int OutSize = 0;   
  11.     jint DecodeSize = -1;   
  12.   
  13.     jbyte *InJbyte = 0;   
  14.     jbyte *OutJbyte = 0;   
  15.   
  16.     jbyteArray InByteArrary = 0;   
  17.     jbyteArray OutByteArrary = 0;   
  18.   
  19.     //获取Input/Out ByteBuffer相关属性   
  20.     {   
  21.         //Input   
  22.         {   
  23.             jclass ByteBufferClass = env->GetObjectClass(pInBuffer);   
  24.             jmethodID PositionMethodId = env->GetMethodID(ByteBufferClass,"position","()I");   
  25.             jmethodID RemainingMethodId = env->GetMethodID(ByteBufferClass,"remaining","()I");   
  26.             jmethodID ArraryMethodId = env->GetMethodID(ByteBufferClass,"array","()[B");   
  27.                
  28.             InPosition = env->CallIntMethod(pInBuffer,PositionMethodId);   
  29.             InRemaining = env->CallIntMethod(pInBuffer,RemainingMethodId);   
  30.             InSize = InPosition + InRemaining;   
  31.                
  32.             InByteArrary = (jbyteArray)env->CallObjectMethod(pInBuffer,ArraryMethodId);   
  33.            
  34.             InJbyte = env->GetByteArrayElements(InByteArrary,0);   
  35.                
  36.             In = (unsigned char*)InJbyte + InPosition;   
  37.         }   
  38.   
  39.         //Output   
  40.         {   
  41.             jclass ByteBufferClass = env->GetObjectClass(pOutBuffer);   
  42.             jmethodID ArraryMethodId = env->GetMethodID(ByteBufferClass,"array","()[B");   
  43.             jmethodID ClearMethodId = env->GetMethodID(ByteBufferClass,"clear","()Ljava/nio/Buffer;");   
  44.                
  45.             //清理输出缓存区   
  46.             env->CallObjectMethod(pOutBuffer,ClearMethodId);   
  47.   
  48.             OutByteArrary = (jbyteArray)env->CallObjectMethod(pOutBuffer,ArraryMethodId);   
  49.             OutJbyte = env->GetByteArrayElements(OutByteArrary,0);   
  50.   
  51.             Out = (unsigned char*)OutJbyte;   
  52.         }   
  53.     }   
  54.   
  55.     //解码   
  56.     DecodeSize = pDecode->DecodeOneFrame(In,InRemaining,Out,OutSize);   
  57.   
  58.     //设置Input/Output ByteBuffer相关属性   
  59.     {   
  60.         //Input   
  61.         {   
  62.             jclass ByteBufferClass = env->GetObjectClass(pInBuffer);   
  63.             jmethodID SetPositionMethodId = env->GetMethodID(ByteBufferClass,"position","(I)Ljava/nio/Buffer;");   
  64.                
  65.             //设置输入缓冲区偏移   
  66.             env->CallObjectMethod(pInBuffer,SetPositionMethodId,InPosition + DecodeSize);   
  67.         }   
  68.   
  69.         //Output   
  70.         {   
  71.             jclass ByteBufferClass = env->GetObjectClass(pOutBuffer);   
  72.             jmethodID SetPositionMethodId = env->GetMethodID(ByteBufferClass,"position","(I)Ljava/nio/Buffer;");   
  73.   
  74.             //设置输出缓冲区偏移   
  75.             env->CallObjectMethod(pOutBuffer,SetPositionMethodId,OutSize);   
  76.         }   
  77.     }   
  78.   
  79.     //清理   
  80.     env->ReleaseByteArrayElements(InByteArrary,InJbyte,0);   
  81.     env->ReleaseByteArrayElements(OutByteArrary,OutJbyte,0);   
  82.   
  83.     return DecodeSize;   
  84. }   
  85.   
  86. JNIEXPORT jlong JNICALL Java_ophone_streaming_video_h264_H264decode_Initialize   
  87.   (JNIEnv * env, jclass obj) {   
  88.   
  89.     H264Decode *pDecode = H264Decode::H264DecodeConstruct();   
  90.     return (jlong)pDecode;   
  91. }   
  92.   
  93. JNIEXPORT void JNICALL Java_ophone_streaming_video_h264_H264decode_Destroy   
  94.   (JNIEnv * env, jclass obj, jlong decode) {   
  95.   
  96.     H264Decode *pDecode = (H264Decode *)decode;   
  97.     if (pDecode)   
  98.     {   
  99.         delete pDecode;   
  100.         pDecode = NULL;   
  101.     }   

 5.3.3 编译本地方法

        接下来,只需要把用C实现的本地方法编译为动态链接库,如果之前你用于移植的那个库曾经移植到Symbian上过,那么编译会相当简单,因为NDK的编译器和Symbian的编译器一样,都是采用GCC做交叉编译器。

        首先,需要在$NDK/apps目录下,创建一个项目目录,这里创建了一个H264Decode目录,在H264Decode目录中,创建一个Android.mk文件:

 

 

  1. APP_PROJECT_PATH := $(call my-dir)   
  2. APP_MODULES      := H264Decode 

  接下来,需要在$NDK/source目录下,创建源代码目录(这里的目录名要和上面创建的项目目录文件名相同),这里创建一个H264Decode目录,然后把之前生成的JNI头文件和你实现的本地方法相关头文件和源代码,都拷贝到   这个目录下面。

 

编写库测试程序

/**  
 * @author ophone
 * @email 3751624@qq.com
 */

package ophone.streaming.video.h264;

import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.nio.ByteBuffer;
import OPhone.app.Activity;
import OPhone.graphics.BitmapFactory;
import OPhone.os.Bundle;
import OPhone.os.Handler;
import OPhone.os.Message;
import OPhone.widget.ImageView;
import OPhone.widget.TextView;

public class H264Example extends Activity {
   
    private static final int VideoWidth = 352;
    private static final int VideoHeight = 288;
   
    private ImageView ImageLayout = null;
    private TextView FPSLayout = null;
    private H264decode Decode = null;
    private Handler H = null;
    private byte[] Buffer = null;
   
    private int DecodeCount = 0;
    private long StartTime = 0;

    public void onCreate(Bundle savedInstanceState) {
       
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
       
        ImageLayout = (ImageView) findViewById(R.id.ImageView);
        FPSLayout = (TextView) findViewById(R.id.TextView);
        Decode = new H264decode();
       
        StartTime = System.currentTimeMillis();
       
        new Thread(new Runnable(){
            public void run() {
                StartDecode();
            }
        }).start();
       
        H = new Handler(){
            public void handleMessage(Message msg) {
                ImageLayout.invalidate();
                ImageLayout.setImageBitmap(BitmapFactory.decodeByteArray(Buffer, 0, Buffer.length));
               
                long Time = (System.currentTimeMillis()-StartTime)/1000;
                if(Time > 0){
                    FPSLayout.setText("花费时间:" + Time + "秒  解码帧数:" + DecodeCount + "  FPS:" + (DecodeCount/Time) );
                }
            }
        };
    }
   
    private void StartDecode(){
       
        File h264file = new File("/tmp/Demo.264");
        InputStream h264stream = null;
        try {
           
            h264stream = new FileInputStream(h264file);
            ByteBuffer pInBuffer = ByteBuffer.allocate(51200);//分配50k的缓存
            ByteBuffer pRGBBuffer = ByteBuffer.allocate(VideoWidth*VideoHeight*3);
           
            while (h264stream.read(pInBuffer.array(), pInBuffer.position(), pInBuffer.remaining()) >= 0) {
               
                pInBuffer.position(0);
                do{
                    int DecodeLength = Decode.DecodeOneFrame(pInBuffer, pRGBBuffer);
                   
                    //如果解码成功,把解码出来的图片显示出来
                    if(DecodeLength > 0 && pRGBBuffer.position() > 0){
                       
                        //转换RGB字节为BMP
                        BMPImage bmp = new BMPImage(pRGBBuffer.array(),VideoWidth,VideoHeight);
                        Buffer = bmp.getByte();
           
                        H.sendMessage(H.obtainMessage());

                        Thread.sleep(1);
                        DecodeCount ++;
                    }
                   
                }while(pInBuffer.remaining() > 10240);//确保缓存区里面的数据始终大于10k
               
                //清理已解码缓冲区
                int Remaining = pInBuffer.remaining();
                System.arraycopy(pInBuffer.array(), pInBuffer.position(), pInBuffer.array(), 0, Remaining);
                pInBuffer.position(Remaining);
            }
           
        } catch (Exception e1) {
            e1.printStackTrace();
        } finally {
            try{h264stream.close();} catch(Exception e){}
        }
       
    }

    protected void onDestroy() {
        super.onDestroy();
        Decode.Cleanup();
    }
}

 

BMPImage是一个工具类,主要用于把RGB序列,转换为BMP图象用于显示:

 

@author ophone
 * @email 3751624@qq.com
*/

package ophone.streaming.video.h264;

import java.nio.ByteBuffer;

public class BMPImage {

    // --- 私有常量
    private final static int BITMAPFILEHEADER_SIZE = 14;
    private final static int BITMAPINFOHEADER_SIZE = 40;

    // --- 位图文件标头
    private byte bfType[] = { 'B', 'M' };
    private int bfSize = 0;
    private int bfReserved1 = 0;
    private int bfReserved2 = 0;
    private int bfOffBits = BITMAPFILEHEADER_SIZE + BITMAPINFOHEADER_SIZE;

    // --- 位图信息标头
    private int biSize = BITMAPINFOHEADER_SIZE;
    private int biWidth = 176;
    private int biHeight = 144;
    private int biPlanes = 1;
    private int biBitCount = 24;
    private int biCompression = 0;
    private int biSizeImage = biWidth*biHeight*3;
    private int biXPelsPerMeter = 0x0;
    private int biYPelsPerMeter = 0x0;
    private int biClrUsed = 0;
    private int biClrImportant = 0;
   
    ByteBuffer bmpBuffer = null;
   
    public BMPImage(byte[] Data,int Width,int Height){
        biWidth = Width;
        biHeight = Height;
       
        biSizeImage = biWidth*biHeight*3;
        bfSize = BITMAPFILEHEADER_SIZE + BITMAPINFOHEADER_SIZE + biWidth*biHeight*3;
        bmpBuffer = ByteBuffer.allocate(BITMAPFILEHEADER_SIZE + BITMAPINFOHEADER_SIZE + biWidth*biHeight*3);
       
        writeBitmapFileHeader();
        writeBitmapInfoHeader();
        bmpBuffer.put(Data);
    }
   
    public byte[] getByte(){
        return bmpBuffer.array();
    }
   
    private byte[] intToWord(int parValue) {

        byte retValue[] = new byte[2];

        retValue[0] = (byte) (parValue & 0x00FF);
        retValue[1] = (byte) ((parValue >> 8) & 0x00FF);

        return (retValue);
    }

    private byte[] intToDWord(int parValue) {

        byte retValue[] = new byte[4];

        retValue[0] = (byte) (parValue & 0x00FF);
        retValue[1] = (byte) ((parValue >> 8) & 0x000000FF);
        retValue[2] = (byte) ((parValue >> 16) & 0x000000FF);
        retValue[3] = (byte) ((parValue >> 24) & 0x000000FF);

        return (retValue);

    }
   
    private void writeBitmapFileHeader () {
       
        bmpBuffer.put(bfType);
        bmpBuffer.put(intToDWord (bfSize));
        bmpBuffer.put(intToWord (bfReserved1));
        bmpBuffer.put(intToWord (bfReserved2));
        bmpBuffer.put(intToDWord (bfOffBits));
       
    }
   
    private void writeBitmapInfoHeader () {
       
        bmpBuffer.put(intToDWord (biSize));   
        bmpBuffer.put(intToDWord (biWidth));   
        bmpBuffer.put(intToDWord (biHeight));   
        bmpBuffer.put(intToWord (biPlanes));   
        bmpBuffer.put(intToWord (biBitCount));   
        bmpBuffer.put(intToDWord (biCompression));   
        bmpBuffer.put(intToDWord (biSizeImage));   
        bmpBuffer.put(intToDWord (biXPelsPerMeter));   
        bmpBuffer.put(intToDWord (biYPelsPerMeter));   
        bmpBuffer.put(intToDWord (biClrUsed));   
        bmpBuffer.put(intToDWord (biClrImportant));
       
    }
}

 

来自:http://www.ophonesdn.com/article/show/45