1. Android FFmpeg开发基本流程
（1）X264/FFmpeg + NDK编译
（2）ffmpeg.so + 编解码C代码
（3）Android.mk 编译
（4）JNI
（5）Java代码调用
基本流程如下图所示：
本文涉及FFmpeg，x264编译。
2. NDK配置
首先需要配置NDK开发环境，略
（1）设置$NDK环境变量
# Detect NDKif [[ -z "$NDK" ]]; then echo "The NDK dir is empty, If the shell can not run normally, you should set the NDK variable to your local ndk.dir" exit 1fi
（2）检查系统类型
OS=`uname`HOST_ARCH=`uname -m`export CCACHE=; type ccache >/dev/null 2>&1 && export CCACHE=ccacheif [ $OS == 'Linux' ]; then export HOST_SYSTEM=linux-$HOST_ARCHelif [ $OS == 'Darwin' ]; then export HOST_SYSTEM=darwin-$HOST_ARCHfi
（3）配置Sysroot和cross_prefix
SYSROOT=$NDK/platforms/android-16/arch-armCROSS_PREFIX=$NDK/toolchains/arm-linux-androideabi-4.9/prebuilt/$HOST_SYSTEM/bin/arm-linux-androideabi-
2. x264编译
2.1 下载源代码
git clone http://git.videolan.org/git/x264.git
2.2 编译脚本
#!/bin/bashecho "###### 开始编译 x264 ######"SOURCE=$TARGET_X264_DIRcd $SOURCEEXTRA_CFLAGS="-march=armv7-a -mfloat-abi=softfp -mfpu=neon -D__ARM_ARCH_7__ -D__ARM_ARCH_7A__"EXTRA_LDFLAGS="-nostdlib"./configure \ --prefix=$PREFIX \ --cross-prefix=$CROSS_PREFIX \ --extra-cflags="$EXTRA_CFLAGS" \ --extra-ldflags="$EXTRA_LDFLAGS" \ --enable-static \ --enable-pic \ --enable-strip \ --disable-cli \ --host=arm-linux \ --sysroot=$SYSROOTmake cleanmake && make install
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
- 23
- 24
- 25
- 26
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
- 23
- 24
- 25
- 26
这里面需要注意的是：
（1）PREFIX指定的是编译输出路径,不指定默认是/usr/local/lib和/usr/local/include
这里讲ffmpeg和x264统一放在工程根目录中build文件夹
（2）编译时不能进行多线程，否则汇编优化报错，如下：
make -j4
make: [common/arm/deblock-a.o] Error 127 (ignored)
/Users/guohe/Android/android-ndk/toolchains/arm-Linux-androideabi-4.9/prebuilt/darwin-x86_64/bin/arm-linux-androideabi-gcc -I. -I. -c -DSTACK_ALIGNMENT=4 -DPIC -DHIGH_BIT_DEPTH=0 -DBIT_DEPTH=8 -o common/arm/predict-a.o common/arm/predict-a.S
/bin/sh: j4: command not found
2.3. 结论
Linux中编译x264：
sudo ./configure --enable-shared --prefix=/usr/localsudo makesudo make install
通过对比发现：Android中编译x264，最基本的就是配置SYSROOT和CROSS_PREFIX
3. 编译FFmpeg
3.1 下载源代码
git clone git://source.ffmpeg.org/ffmpeg.git $FFMPEG_SOURCE_DIR
3.2 编译脚本
ADD_H264_FEATURE="--enable-encoder=aac \ --enable-decoder=aac \ --enable-encoder=libx264 \ --enable-libx264 \ --extra-cflags=-I$PREFIX/include \ --extra-ldflags=-L$PREFIX/lib "
./configure \ --prefix=$PREFIX \ --enable-pthreads \ --enable-gpl \ --enable-version3 \ --enable-nonfree \ --enable-static \ --enable-small \ --enable-asm \ --enable-neon \ --cross-prefix=$CROSS_PREFIX \ --target-os=linux \ --arch=arm \ --enable-cross-compile \ --sysroot=$SYSROOT \ $ADD_H264_FEATURE make clean make -j4 make install
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
注：
（1）跨平台编译特殊配置
–sysroot=SYSROOT–cross−prefix=CROSS_PREFIX
–target-os=linux
（2）支持x264
–enable-encoder=libx264 \
–enable-libx264 \
–extra-cflags=-IPREFIX/include –extra−ldflags=−LPREFIX/lib
（3）编译优化
–enable-asm \
–enable-neon \
3.3 编译结果
至此，ffmpeg和x264已经编译完成，编译结果如下：
4. NDK + FFmpeg开发
ffmpeg，x264已经编译完成，下面就聊聊怎么用ffmpeg库进行开发。
下面展示一个基于FFmpeg开发的解码程序，其功能是从一个视频中解码5帧数据。
4.1 复制编译FFmpeg,x264库与头文件
cp $PREFIX/lib/*.a ./jni/libcp -r $PREFIX/include/* ./jni/
4.2 编写Android.mk
Android.mk主要包含几下几块：
（1）引入库文件
libavcodec.a libavdevice.a libavfilter.a libavformat.a libavutil.a libpostproc.a libswresample.a libswscale.a libx264.a
include $(CLEAR_VARS)LOCAL_MODULE:= libavutil_staticLOCAL_SRC_FILES:= lib/libavutil.aLOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)include $(PREBUILT_STATIC_LIBRARY)
（2）编译源文件
需要设置：
LOCAL_MODULE //库名称
LOCAL_SRC_FILES //源代码文件
LOCAL_LDLIBS //额外链接的库
LOCAL_CFLAGS //CFlags
（3）编译何种类型
include $(BUILD_SHARED_LIBRARY)
（4）详细脚本如下
LOCAL_PATH := $(call my-dir)include $(CLEAR_VARS)LOCAL_MODULE:= libavcodec_staticLOCAL_SRC_FILES:= lib/libavcodec.aLOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)include $(PREBUILT_STATIC_LIBRARY)include $(CLEAR_VARS)LOCAL_MODULE:= libavformat_staticLOCAL_SRC_FILES:= lib/libavformat.aLOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)include $(PREBUILT_STATIC_LIBRARY)include $(CLEAR_VARS)LOCAL_MODULE:= libswscale_staticLOCAL_SRC_FILES:= lib/libswscale.aLOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)include $(PREBUILT_STATIC_LIBRARY)include $(CLEAR_VARS)LOCAL_MODULE:= libavutil_staticLOCAL_SRC_FILES:= lib/libavutil.aLOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)include $(PREBUILT_STATIC_LIBRARY)include $(CLEAR_VARS)LOCAL_MODULE:= libavdevice_staticLOCAL_SRC_FILES:= lib/libavdevice.aLOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)include $(PREBUILT_STATIC_LIBRARY)include $(CLEAR_VARS)LOCAL_MODULE:= libavfilter_staticLOCAL_SRC_FILES:= lib/libavfilter.aLOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)include $(PREBUILT_STATIC_LIBRARY)include $(CLEAR_VARS)LOCAL_MODULE:= libswresample_staticLOCAL_SRC_FILES:= lib/libswresample.aLOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)include $(PREBUILT_STATIC_LIBRARY)include $(CLEAR_VARS)LOCAL_MODULE:= libpostproc_staticLOCAL_SRC_FILES:= lib/libpostproc.aLOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)include $(PREBUILT_STATIC_LIBRARY)include $(CLEAR_VARS)LOCAL_MODULE:= libx264_staticLOCAL_SRC_FILES:= lib/libx264.aLOCAL_CFLAGS := -march=armv7-a -mfloat-abi=softfp -mfpu=neon -O3 -ffast-math -funroll-loopsLOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)include $(PREBUILT_STATIC_LIBRARY)include $(CLEAR_VARS)LOCAL_MODULE := ffmpegLOCAL_SRC_FILES := decoder.c encoder.cLOCAL_LDLIBS := -llog -lzLOCAL_CFLAGS := -march=armv7-a -mfloat-abi=softfp -mfpu=neon -O3 -ffast-math -funroll-loopsLOCAL_WHOLE_STATIC_LIBRARIES := libavformat_static \ libavcodec_static \ libavutil_static \ libpostproc_static \ libswscale_static \ libswresample_static \ libx264_static \ libavfilter_static \ libavdevice_static \include $(BUILD_SHARED_LIBRARY)
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
- 23
- 24
- 25
- 26
- 27
- 28
- 29
- 30
- 31
- 32
- 33
- 34
- 35
- 36
- 37
- 38
- 39
- 40
- 41
- 42
- 43
- 44
- 45
- 46
- 47
- 48
- 49
- 50
- 51
- 52
- 53
- 54
- 55
- 56
- 57
- 58
- 59
- 60
- 61
- 62
- 63
- 64
- 65
- 66
- 67
- 68
- 69
- 70
- 71
- 72
- 73
- 74
- 75
- 76
- 77
- 78
- 79
- 80
- 81
- 82
- 83
- 84
- 85
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
- 23
- 24
- 25
- 26
- 27
- 28
- 29
- 30
- 31
- 32
- 33
- 34
- 35
- 36
- 37
- 38
- 39
- 40
- 41
- 42
- 43
- 44
- 45
- 46
- 47
- 48
- 49
- 50
- 51
- 52
- 53
- 54
- 55
- 56
- 57
- 58
- 59
- 60
- 61
- 62
- 63
- 64
- 65
- 66
- 67
- 68
- 69
- 70
- 71
- 72
- 73
- 74
- 75
- 76
- 77
- 78
- 79
- 80
- 81
- 82
- 83
- 84
- 85
4.3 解码程序
Native程序一般分为两块：
（1）JNI调用接口
/* * Class: com_example_jnidemo_MainActivity * Method: info * Signature: (Ljava/lang/String;)V */JNIEXPORT void JNICALL Java_com_example_jnidemo_MainActivity_info (JNIEnv *, jobject, jstring);
（2）功能模块
略
详细代码如下：
#include <jni.h>#include <android/log.h>#include <stdio.h>#include <libavcodec/avcodec.h>#include <libavformat/avformat.h>#include <libavformat/avio.h>#include <libavutil/fifo.h>#include <libavutil/avutil.h>#include <libavutil/mem.h>#include <libswscale/swscale.h>#include "com_example_jnidemo_MainActivity.h"#define LOG_TAG "FFMPEG INFO"#define LOGI(...) __android_log_print(ANDROID_LOG_INFO,LOG_TAG,__VA_ARGS__)#define LOGE(...) __android_log_print(ANDROID_LOG_ERROR,LOG_TAG,__VA_ARGS__)void SaveFrame(AVFrame *pFrame, int width, int height, int iFrame) { FILE* pFile; char szFileName[32]; int y; sprintf(szFileName,"/mnt/sdcard/test/frame%d.ppm",iFrame); LOGI("filename : %s",szFileName); pFile = fopen(szFileName,"w"); if(pFile == NULL){ LOGI("can not open file %s",szFileName); return ; } fprintf(pFile,"P6\n%d %d\n255\n",width,height); for(y=0;y<width;++y){ LOGI("Write file AVFrame"); fwrite(pFrame->data[0]+y*pFrame->linesize[0],1,width*3,pFile); } fclose(pFile); LOGI("close file %s",szFileName);}JNIEXPORT void JNICALL Java_com_example_jnidemo_MainActivity_info(JNIEnv *env, jobject obj, jstring jpath){ const jbyte* path = (*env)->GetStringUTFChars(env,jpath,NULL); AVFormatContext *pFormatCtx = NULL; int i, videoStream; AVCodecContext *pCodecCtxOrig = NULL; AVCodecContext *pCodecCtx = NULL; AVCodec *pCodec = NULL; AVFrame *pFrame = NULL; AVFrame *pFrameRGB = NULL; AVPacket packet; int frameFinished; int numBytes; uint8_t *buffer = NULL; struct SwsContext *sws_ctx = NULL; av_register_all(); int err_code; if(err_code=avformat_open_input(&pFormatCtx, path, NULL, NULL)) { char buf[256]; av_strerror(err_code, buf, 1024); LOGE("Couldn't open file %s: %d(%s)", path, err_code, buf); return; } if(avformat_find_stream_info(pFormatCtx, NULL)<0) return ; av_dump_format(pFormatCtx, 0, path, 0); videoStream=-1; for(i=0; i<pFormatCtx->nb_streams; i++) if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO) { videoStream=i; break; } if(videoStream==-1) return ; pCodecCtxOrig=pFormatCtx->streams[videoStream]->codec; pCodec=avcodec_find_decoder(pCodecCtxOrig->codec_id); if(pCodec==NULL) { LOGE("Unsupported codec!\n"); return ; } pCodecCtx = avcodec_alloc_context3(pCodec); if(avcodec_copy_context(pCodecCtx, pCodecCtxOrig) != 0) { LOGE("Couldn't copy codec context"); return ; } if(avcodec_open2(pCodecCtx, pCodec, NULL)<0) return ; pFrame=av_frame_alloc(); pFrameRGB=av_frame_alloc(); if(pFrameRGB==NULL) return ; numBytes=avpicture_get_size(AV_PIX_FMT_RGB24, pCodecCtx->width,pCodecCtx->height); buffer=(uint8_t *)av_malloc(numBytes*sizeof(uint8_t)); avpicture_fill((AVPicture *)pFrameRGB, buffer, AV_PIX_FMT_RGB24,pCodecCtx->width, pCodecCtx->height); sws_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height, AV_PIX_FMT_RGB24, SWS_BILINEAR, NULL, NULL, NULL ); i=0; while(av_read_frame(pFormatCtx, &packet)>=0) { if(packet.stream_index==videoStream) { avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet); if(frameFinished) { sws_scale(sws_ctx, (uint8_t const * const *)pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pFrameRGB->data, pFrameRGB->linesize); if(++i<=5) SaveFrame(pFrameRGB, pCodecCtx->width, pCodecCtx->height, i); } } av_free_packet(&packet); } av_free(buffer); av_frame_free(&pFrameRGB); av_frame_free(&pFrame); avcodec_close(pCodecCtx); avcodec_close(pCodecCtxOrig); avformat_close_input(&pFormatCtx); (*env)->ReleaseStringUTFChars(env,jpath,path);}
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
- 23
- 24
- 25
- 26
- 27
- 28
- 29
- 30
- 31
- 32
- 33
- 34
- 35
- 36
- 37
- 38
- 39
- 40
- 41
- 42
- 43
- 44
- 45
- 46
- 47
- 48
- 49
- 50
- 51
- 52
- 53
- 54
- 55
- 56
- 57
- 58
- 59
- 60
- 61
- 62
- 63
- 64
- 65
- 66
- 67
- 68
- 69
- 70
- 71
- 72
- 73
- 74
- 75
- 76
- 77
- 78
- 79
- 80
- 81
- 82
- 83
- 84
- 85
- 86
- 87
- 88
- 89
- 90
- 91
- 92
- 93
- 94
- 95
- 96
- 97
- 98
- 99
- 100
- 101
- 102
- 103
- 104
- 105
- 106
- 107
- 108
- 109
- 110
- 111
- 112
- 113
- 114
- 115
- 116
- 117
- 118
- 119
- 120
- 121
- 122
- 123
- 124
- 125
- 126
- 127
- 128
- 129
- 130
- 131
- 132
- 133
- 134
- 135
- 136
- 137
- 138
- 139
- 140
- 141
- 142
- 143
- 144
- 145
- 146
- 147
- 148
- 149
- 150
- 151
- 152
- 153
- 154
- 155
- 156
- 157
- 158
- 159
- 160
- 161
- 162
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
- 23
- 24
- 25
- 26
- 27
- 28
- 29
- 30
- 31
- 32
- 33
- 34
- 35
- 36
- 37
- 38
- 39
- 40
- 41
- 42
- 43
- 44
- 45
- 46
- 47
- 48
- 49
- 50
- 51
- 52
- 53
- 54
- 55
- 56
- 57
- 58
- 59
- 60
- 61
- 62
- 63
- 64
- 65
- 66
- 67
- 68
- 69
- 70
- 71
- 72
- 73
- 74
- 75
- 76
- 77
- 78
- 79
- 80
- 81
- 82
- 83
- 84
- 85
- 86
- 87
- 88
- 89
- 90
- 91
- 92
- 93
- 94
- 95
- 96
- 97
- 98
- 99
- 100
- 101
- 102
- 103
- 104
- 105
- 106
- 107
- 108
- 109
- 110
- 111
- 112
- 113
- 114
- 115
- 116
- 117
- 118
- 119
- 120
- 121
- 122
- 123
- 124
- 125
- 126
- 127
- 128
- 129
- 130
- 131
- 132
- 133
- 134
- 135
- 136
- 137
- 138
- 139
- 140
- 141
- 142
- 143
- 144
- 145
- 146
- 147
- 148
- 149
- 150
- 151
- 152
- 153
- 154
- 155
- 156
- 157
- 158
- 159
- 160
- 161
- 162
4.4 编译native程序
进入jni目录，执行：
$NDK_PATH/ndk-build
编译结果：
编译完成后，在lib目录下可以看到编译的so文件，在Android.mk中设置的库文件名为ffmpeg，那么编译的文件应该是”libffmpeg.so”
4.5 JAVA调用JNI
（1）加载库文件
static { System.loadLibrary("ffmpeg"); }
（2）JNI接口
所有的JNI接口都有native关键字
private native void info(String path);
（3）详细代码
package com.example.jnidemo;import android.app.Activity;import android.os.Bundle;import android.os.Environment;public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); String path = "/sdcard/test/test.mp4"; info(path); } private native void info(String path); static { System.loadLibrary("ffmpeg"); }}
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
- 23
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
- 23
5. 项目源码
AndroidFFmpeg
