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Android 编译FFmpeg x264

2017-06-09 19:40 423 查看
原文：http://blog.csdn.net/matrix_laboratory/article/details/56490404


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$NDK环境变量
# Detect NDK
if [[  -z "$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 1
fi
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（2）检查系统类型
# Detect OS
OS=`uname`
HOST_ARCH=`uname -m`
export CCACHE=; type ccache >/dev/null 2>&1 && export CCACHE=ccache
if [ $OS == 'Linux' ]; then
export HOST_SYSTEM=linux-$HOST_ARCH
elif [ $OS == 'Darwin' ]; then
export HOST_SYSTEM=darwin-$HOST_ARCH
fi
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（3）配置Sysroot和cross_prefix
SYSROOT=$NDK/platforms/android-16/arch-arm
CROSS_PREFIX=$NDK/toolchains/arm-linux-androideabi-4.9/prebuilt/$HOST_SYSTEM/bin/arm-linux-androideabi-
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2. x264编译


2.1 下载源代码

git clone http://git.videolan.org/git/x264.git
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2.2 编译脚本

#!/bin/bash

echo "###### 开始编译 x264 ######"

SOURCE=$TARGET_X264_DIR
cd $SOURCE
#PREFIX指定的是编译输出路径,不指定默认是/usr/local/lib和/usr/local/include
#PREFIX=../build

EXTRA_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=$SYSROOT

make clean
make && make install
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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
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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/local
sudo make
sudo make install
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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
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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 "
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./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
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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/lib
cp -r $PREFIX/include/* ./jni/
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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
#static version of libavutil
include $(CLEAR_VARS)
LOCAL_MODULE:= libavutil_static
LOCAL_SRC_FILES:= lib/libavutil.a
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)
include $(PREBUILT_STATIC_LIBRARY)
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（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)
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（4）详细脚本如下
LOCAL_PATH := $(call my-dir)

#include $(call all-subdir-makefiles)

#static version of libavcodec
include $(CLEAR_VARS)
LOCAL_MODULE:= libavcodec_static
LOCAL_SRC_FILES:= lib/libavcodec.a
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)
include $(PREBUILT_STATIC_LIBRARY)

#static version of libavformat
include $(CLEAR_VARS)
LOCAL_MODULE:= libavformat_static
LOCAL_SRC_FILES:= lib/libavformat.a
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)
include $(PREBUILT_STATIC_LIBRARY)

#static version of libswscale
include $(CLEAR_VARS)
LOCAL_MODULE:= libswscale_static
LOCAL_SRC_FILES:= lib/libswscale.a
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)
include $(PREBUILT_STATIC_LIBRARY)

#static version of libavutil
include $(CLEAR_VARS)
LOCAL_MODULE:= libavutil_static
LOCAL_SRC_FILES:= lib/libavutil.a
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)
include $(PREBUILT_STATIC_LIBRARY)

#static version of libavdevice
include $(CLEAR_VARS)
LOCAL_MODULE:= libavdevice_static
LOCAL_SRC_FILES:= lib/libavdevice.a
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)
include $(PREBUILT_STATIC_LIBRARY)

#static version of libavfilter
include $(CLEAR_VARS)
LOCAL_MODULE:= libavfilter_static
LOCAL_SRC_FILES:= lib/libavfilter.a
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)
include $(PREBUILT_STATIC_LIBRARY)

#static version of libswresample
include $(CLEAR_VARS)
LOCAL_MODULE:= libswresample_static
LOCAL_SRC_FILES:= lib/libswresample.a
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)
include $(PREBUILT_STATIC_LIBRARY)

#static version of libpostproc
include $(CLEAR_VARS)
LOCAL_MODULE:= libpostproc_static
LOCAL_SRC_FILES:= lib/libpostproc.a
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)
include $(PREBUILT_STATIC_LIBRARY)

#static version of libx264
include $(CLEAR_VARS)
LOCAL_MODULE:= libx264_static
LOCAL_SRC_FILES:= lib/libx264.a
LOCAL_CFLAGS := -march=armv7-a -mfloat-abi=softfp -mfpu=neon -O3 -ffast-math -funroll-loops
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)
include $(PREBUILT_STATIC_LIBRARY)

include $(CLEAR_VARS)

LOCAL_MODULE := ffmpeg
LOCAL_SRC_FILES := decoder.c encoder.c
LOCAL_LDLIBS := -llog -lz
LOCAL_CFLAGS := -march=armv7-a -mfloat-abi=softfp -mfpu=neon -O3 -ffast-math -funroll-loops
LOCAL_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)
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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);
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（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();

//      if(avformat_open_input(&pFormatCtx, path, NULL, NULL)!=0)
//      {
//          LOGE("Could not open the file : %s",path);
//          return ;
//    }

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);
}
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4.4 编译native程序

进入jni目录，执行：
$NDK_PATH/ndk-build
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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");
}
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（2）JNI接口 

所有的JNI接口都有native关键字
private native void info(String path);
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（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");
}

}
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