最近弄了下android ffmpeg解码，下面把流程总结一下方便大家参考
1.ffmpeg移植
网上有一些关于ffmpeg移植的文章，试了很多次但是最后生成的libffmpeg.so就只有几KB所以这里换一种方式，网上也有文章说到了，其实我觉得这种方式反而要好一点，只需要生成一个库就行了。
我修改好的ffmpeg下载地址：http://download.csdn.net/detail/hclydao/6865961
下载后，解压进入ffmpeg-1.2.4-android目录，里面有一个mkconfig.sh文件，打开这个文件，你需要修改几个地方.
mkconfig.sh内容如下:
#!/bin/shexport PREBUILT=/dao/work/tools/android-ndk-r5b/toolchains/arm-linux-androideabi-4.4.3export PLATFORM=/dao/work/tools/android-ndk-r5b/platforms/android-9/arch-armexport TMPDIR=/dao/tmp./configure --target-os=linux --arch=arm --disable-ffmpeg --disable-ffplay --disable-ffprobe --disable-ffserver --disable-avdevice --disable-avfilter --disable-postproc --disable-swresample --disable-avresample --disable-symver --disable-debug --disable-stripping --disable-yasm --disable-asm --enable-gpl --enable-version3 --enable-nonfree --disable-doc --enable-static --disable-shared --enable-cross-compile --prefix=/dao/_install --cc=$PREBUILT/prebuilt/linux-x86/bin/arm-linux-androideabi-gcc --cross-prefix=$PREBUILT/prebuilt/linux-x86/bin/arm-linux-androideabi- --nm=$PREBUILT/prebuilt/linux-x86/bin/arm-linux-androideabi-nm --extra-cflags="-fPIC -DANDROID -I$PLATFORM/usr/include" --extra-ldflags="-L$PLATFORM/usr/lib -nostdlib"sed -i 's/HAVE_LRINT 0/HAVE_LRINT 1/g' config.h sed -i 's/HAVE_LRINTF 0/HAVE_LRINTF 1/g' config.h sed -i 's/HAVE_ROUND 0/HAVE_ROUND 1/g' config.h sed -i 's/HAVE_ROUNDF 0/HAVE_ROUNDF 1/g' config.h sed -i 's/HAVE_TRUNC 0/HAVE_TRUNC 1/g' config.h sed -i 's/HAVE_TRUNCF 0/HAVE_TRUNCF 1/g' config.h sed -i 's/HAVE_CBRT 0/HAVE_CBRT 1/g' config.h sed -i 's/HAVE_CBRTF 0/HAVE_CBRTF 1/g' config.h sed -i 's/HAVE_ISINF 0/HAVE_ISINF 1/g' config.h sed -i 's/HAVE_ISNAN 0/HAVE_ISNAN 1/g' config.h sed -i 's/HAVE_SINF 0/HAVE_SINF 1/g' config.h sed -i 's/HAVE_RINT 0/HAVE_RINT 1/g' config.hsed -i 's/#define av_restrict restrict/#define av_restrict/g' config.h最开始的环境变量要设置一下:
export PREBUILT=/dao/work/tools/android-ndk-r5b/toolchains/arm-linux-androideabi-4.4.3export PLATFORM=/dao/work/tools/android-ndk-r5b/platforms/android-9/arch-armexport TMPDIR=/dao/tmp这个为你的NDK的路径，以及临时目录
还有一个地方需要修改:
--prefix=/dao/_install \这个为安装目录，请改成你自己的。
然后执行./mkconfig.sh
应该会有一个警告，不用管。直接执行make几分钟左右应该就会编译完成了，然后执行make install
在你的安装目录下就会生成两个目录include和llib到这里 我们移植就完成了，先把这些文件放在这，后面我们需要用到。
2.jni的编写
在你的android工程目录下新建一个jni的目录(其实我是在另一个工程里新建的，前面我试了一次执行ndk-build的时候把工程里的东西给删除了)，把前面我们安装的include整个目录拷贝到jni目录下，把lib目录里的所有.a文件拷贝到jni目录下,新建Android.mk文件，内容如下:
LOCAL_PATH := $(call my-dir)include $(CLEAR_VARS)LOCAL_MODULE := avformatLOCAL_SRC_FILES := libavformat.aLOCAL_CFLAGS :=-IlibavformatLOCAL_EXPORT_C_INCLUDES := libavformatLOCAL_EXPORT_CFLAGS := -IlibavformatLOCAL_EXPORT_LDLIBS := -lloginclude $(PREBUILT_STATIC_LIBRARY)include $(CLEAR_VARS)LOCAL_MODULE := avcodecLOCAL_SRC_FILES := libavcodec.aLOCAL_CFLAGS :=-IlibavcodecLOCAL_EXPORT_C_INCLUDES := libavcodecLOCAL_EXPORT_CFLAGS := -IlibavcodecLOCAL_EXPORT_LDLIBS := -lloginclude $(PREBUILT_STATIC_LIBRARY)include $(CLEAR_VARS)LOCAL_MODULE := avutilLOCAL_SRC_FILES := libavutil.aLOCAL_CFLAGS :=-IlibavutilLOCAL_EXPORT_C_INCLUDES := libavutilLOCAL_EXPORT_CFLAGS := -IlibavutilLOCAL_EXPORT_LDLIBS := -lloginclude $(PREBUILT_STATIC_LIBRARY)include $(CLEAR_VARS)LOCAL_MODULE := swscaleLOCAL_SRC_FILES :=libswscale.aLOCAL_CFLAGS :=-Ilibavutil -IlibswscaleLOCAL_EXPORT_C_INCLUDES := libswscaleLOCAL_EXPORT_CFLAGS := -IlibswscaleLOCAL_EXPORT_LDLIBS := -llog -lavutilinclude $(PREBUILT_STATIC_LIBRARY)include $(CLEAR_VARS)LOCAL_MODULE := ffmpegutilsLOCAL_SRC_FILES := native.cLOCAL_C_INCLUDES := $(LOCAL_PATH)/includeLOCAL_LDLIBS := -L$(LOCAL_PATH) -lm -lzLOCAL_STATIC_LIBRARIES := avformat avcodec avutil swscaleinclude $(BUILD_SHARED_LIBRARY)新建native.c文件，这个是我们最终要调用到的文件，内容如下:
/* * Copyright 2011 - Churn Labs, LLC * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. *//* * This is mostly based off of the FFMPEG tutorial: * http://dranger.com/ffmpeg/ * With a few updates to support Android output mechanisms and to update * places where the APIs have shifted. */#include#include #include #include #include #include #include #define LOG_TAG "FFMPEGSample"#define LOGI(...) __android_log_print(ANDROID_LOG_INFO,LOG_TAG,__VA_ARGS__)#define LOGE(...) __android_log_print(ANDROID_LOG_ERROR,LOG_TAG,__VA_ARGS__)AVCodecContext * pCodecCtx = NULL;AVFrame * pFrame=NULL;AVPacket avpkt;struct SwsContext *swsctx = NULL;AVFrame * picture=NULL;JNIEXPORT jint JNICALL Java_com_dao_iclient_FfmpegIF_getffmpegv(JNIEnv * env, jclass obj){ LOGI("getffmpegv"); return avformat_version();}JNIEXPORT jint JNICALL Java_com_dao_iclient_FfmpegIF_DecodeInit(JNIEnv * env, jclass obj,jint width,jint height){ LOGI("Decode_init"); AVCodec * pCodec=NULL; avcodec_register_all(); //av_register_all(); //avcodec_init(); av_init_packet(&avpkt); pCodec=avcodec_find_decoder(CODEC_ID_H264); if(NULL!=pCodec) { pCodecCtx=avcodec_alloc_context3(pCodec); if(avcodec_open2(pCodecCtx,pCodec,NULL)>=0) { pCodecCtx->height = height; pCodecCtx->width = width; pFrame=avcodec_alloc_frame(); } return 1; } else return 0;}JNIEXPORT jint JNICALL Java_com_dao_iclient_FfmpegIF_Decoding(JNIEnv * env, jclass obj,const jbyteArray pSrcData,const jint DataLen,const jbyteArray pDeData){ //LOGI("Decoding"); int frameFinished; int i,j; int consumed_bytes; jbyte * Buf = (jbyte*)(*env)->GetByteArrayElements(env, pSrcData, 0); jbyte * Pixel= (jbyte*)(*env)->GetByteArrayElements(env, pDeData, 0); avpkt.data = Buf; avpkt.size = DataLen; consumed_bytes=avcodec_decode_video2(pCodecCtx,pFrame,&frameFinished,&avpkt); //av_free_packet(&avpkt); if(frameFinished) { picture=avcodec_alloc_frame(); avpicture_fill((AVPicture *) picture, (uint8_t *)Pixel, PIX_FMT_RGB565,pCodecCtx->width,pCodecCtx->height); swsctx = sws_getContext(pCodecCtx->width,pCodecCtx->height, pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height,PIX_FMT_RGB565, SWS_BICUBIC, NULL, NULL, NULL); sws_scale(swsctx,(const uint8_t* const*)pFrame->data,pFrame->linesize,0,pCodecCtx->height,picture->data,picture->linesize); } (*env)->ReleaseByteArrayElements(env, pSrcData, Buf, 0); (*env)->ReleaseByteArrayElements(env, pDeData, Pixel, 0); return consumed_bytes;}JNIEXPORT jint JNICALL Java_com_dao_iclient_FfmpegIF_DecodeRelease(JNIEnv * env, jclass obj){ //LOGI("Decode_release"); sws_freeContext(swsctx); av_free_packet(&avpkt); av_free(pFrame); av_free(picture); avcodec_close(pCodecCtx); av_free(pCodecCtx); return 1;}
最后我们只用到了两个函数一个是init一个是decoding，这里说明一下函数的命名方式为Java_包名_类名_函数名，com.dao.iclient是我的包名,FfmpegIF是我的类名,DecodeInit是我的函数名.如果你之前已经在系统设置了ndk的环境变量，你就可以直接在工程目录下执行ndk-build(这里目录别弄错了).最后会在工程目录下的libs/armeabi/生成这个库文件.
3.应用ffmpeg库
增加FfmpegIF类,内容如下
package com.dao.iclient;public class FfmpegIF { public static short TYPE_MODE_DATA = 0; public static short TYPE_MODE_COM = 1; public static int VIDEO_COM_START = 0x00; public static int VIDEO_COM_POSE = 0x01; public static int VIDEO_COM_RUN = 0x02; public static int VIDEO_COM_ACK = 0x03; public static int VIDEO_COM_STOP = 0x04; static public native int getffmpegv(); static public native int DecodeInit(int width,int height); static public native int Decoding(byte[] in,int datalen,byte[] out); static public native int DecodeRelease(); static { System.loadLibrary("ffmpegutils"); }}在布局文件里增加一个ImageView对象,我这里是接收到网络传输过来的数据后进行的解码，我把代码都帖上来吧，以下是我的主文件的内容:package com.dao.iclient;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import java.net.Socket;import java.nio.ByteBuffer;import java.util.Timer;import java.util.TimerTask;import android.app.Activity;import android.graphics.Bitmap;import android.graphics.Bitmap.Config;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.os.SystemClock;import android.view.Menu;import android.widget.ImageView;public class IcoolClient extends Activity { public Socket socket; public ByteBuffer buffer; public ByteBuffer Imagbuf; //net package public static short type = 0; public static int packageLen = 0; public static int sendDeviceID = 0; public static int revceiveDeviceID = 0; public static short sendDeviceType = 0; public static int dataIndex = 0; public static int dataLen = 0; public static int frameNum = 0; public static int commType = 0; //size public static int packagesize; public OutputStream outputStream=null; public InputStream inputStream=null; public int width = 0; public int height = 0; public Bitmap VideoBit; public ImageView mImag; public byte[] mout; protected static final int REFRESH = 0; private Handler mHandler; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_icool_client); mImag = (ImageView)findViewById(R.id.mimg); packagesize = 7 * 4 + 2 * 2; buffer = ByteBuffer.allocate(packagesize); // int ffpmegv = FfmpegIF.getffmpegv(); //System.out.println("ffmpeg version is " + ffpmegv); width = 640; height = 480; mout = new byte[width * height * 2]; Imagbuf = ByteBuffer.wrap(mout); VideoBit = Bitmap.createBitmap(width ,height, Config.RGB_565); //mImag.postInvalidate(); int ret = FfmpegIF.DecodeInit(width, height); //System.out.println(" ret is " + ret); mHandler = new Handler(); new StartThread().start(); } final Runnable mUpdateUI = new Runnable() { @Override public void run() { // TODO Auto-generated method stub VideoBit.copyPixelsFromBuffer(Imagbuf); mImag.setImageBitmap(VideoBit); } }; class StartThread extends Thread { @Override public void run() { // TODO Auto-generated method stub //super.run(); int datasize; try { socket = new Socket("192.168.1.15", 9876); //System.out.println("socket"); SendCom(FfmpegIF.VIDEO_COM_STOP); SendCom(FfmpegIF.VIDEO_COM_START); //new ShowBuffer().start(); inputStream = socket.getInputStream(); byte[] Rbuffer = new byte[packagesize]; while(true) { inputStream.read(Rbuffer); //byte2hex(Rbuffer); SystemClock.sleep(3); datasize = getDataL(Rbuffer); if(datasize > 0) { byte[] Data = new byte[datasize]; int size; size = inputStream.read(Data); FfmpegIF.Decoding(Data, size, mout); //VideoBit.copyPixelsFromBuffer(Imagbuf); //mImag.setImageBitmap(VideoBit); mHandler.post(mUpdateUI); //System.out.println("read datalen is " + size); //SystemClock.sleep(10); SendCom(FfmpegIF.VIDEO_COM_ACK); } } }catch (IOException e) { e.printStackTrace(); } } } public void SendCom(int comtype) { byte[] Bbuffer = new byte[packagesize]; try { outputStream = socket.getOutputStream(); type = FfmpegIF.TYPE_MODE_COM; packageLen = packagesize; commType = comtype; putbuffer(); Bbuffer = buffer.array(); outputStream.write(Bbuffer); //System.out.println("send done"); } catch (IOException e) { e.printStackTrace(); } } public void putbuffer(){ buffer.clear(); buffer.put(ShorttoByteArray(type)); buffer.put(InttoByteArray(packageLen)); buffer.put(InttoByteArray(sendDeviceID)); buffer.put(InttoByteArray(revceiveDeviceID)); buffer.put(ShorttoByteArray(sendDeviceType)); buffer.put(InttoByteArray(dataIndex)); buffer.put(InttoByteArray(dataLen)); buffer.put(InttoByteArray(frameNum)); buffer.put(InttoByteArray(commType)); //System.out.println("putbuffer done"); } private static byte[] ShorttoByteArray(short n) { byte[] b = new byte[2]; b[0] = (byte) (n & 0xff); b[1] = (byte) (n >> 8 & 0xff); return b; } private static byte[] InttoByteArray(int n) { byte[] b = new byte[4]; b[0] = (byte) (n & 0xff); b[1] = (byte) (n >> 8 & 0xff); b[2] = (byte) (n >> 16 & 0xff); b[3] = (byte) (n >> 24 & 0xff); return b; } public short getType(byte[] tpbuffer){ short gtype = (short) ((short)tpbuffer[0] + (short)(tpbuffer[1] << 8)); //System.out.println("gtype is " + gtype); return gtype; } public int getPakL(byte[] pkbuffer){ int gPackageLen = ((int)(pkbuffer[2]) & 0xff) | ((int)(pkbuffer[3] & 0xff) << 8) | ((int)(pkbuffer[4] & 0xff) << 16) | ((int)(pkbuffer[5] & 0xff) << 24); //System.out.println("gPackageLen is " + gPackageLen); return gPackageLen; } public int getDataL(byte[] getbuffer){ int gDataLen = (((int)(getbuffer[20] & 0xff)) | ((int)(getbuffer[21] & 0xff) << 8) | ((int)(getbuffer[22] & 0xff) << 16) | ((int)(getbuffer[23] & 0xff) << 24)); //System.out.println("gDataLen is " + gDataLen); return gDataLen; } public int getFrameN(byte[] getbuffer){ int getFrameN = (int)(((int)(getbuffer[24])) + ((int)(getbuffer[25]) << 8) + ((int)(getbuffer[26]) << 16) + ((int)(getbuffer[27]) << 24)); //System.out.println("getFrameN is " + getFrameN); return getFrameN; } private void byte2hex(byte [] buffer) { String h = ""; for(int i = 0; i < buffer.length; i++){ String temp = Integer.toHexString(buffer[i] & 0xFF); if(temp.length() == 1){ temp = "0" + temp; } h = h + " "+ temp; } // System.out.println(h); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.icool_client, menu); return true; }}函数说明:
mUpdateUI用于解决主进程无法刷新UI的问题
StartThread网络通信线程主要工作是在这里，先接收指令包，然后接收数据包,然后解码显示
SendCom指令包发送
putbuffer指令包生成，因为服务器是用C写的，指令包是一个结构体所以这里进行了这样的处理，同时需要注意字节对齐，C语言的long类型是4个字节，Java的long类型为8个字节，这里需要注意，我在这纠结了几个小时。
ShorttoByteArray,InttoByteArray网络通信格式转换，低字节在前高字节在后
getType,getPakL,getDataL,getFrameN，指令包相关数据获取
byte2hex将byte数组转换成十六进制输出，这里是为了调试用.
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作者：hclydao
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