根据ffmpeg 生成android动态库
本次是在Ubuntu上进行编译ffmpeg库的 安装Ubuntu环境
1.安装完Ubuntu之后 使用命令行执行 依次以下命令：
apt-get update
apt-get install yasm
apt-get install pkg-config
2.在Ubuntu中下载ndk 以及 ffmpeg (目前在ubuntu不要使用最新的ndk以及ffmpeg 会出现一些未知的环境错误)
wget https://dl.google.com/android/repository/android-ndk-r14b-linux-x86_64.zip
http://ffmpeg.org/releases/ffmpeg-3.4.5.tar.bz2
3.解压 ndk 以及ffmpeg
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unzip android-ndk-r14b-linux-x86_64.zip (比如解压到/home/wxj/ndk_build/android-ndk-r14b)
tar jxvf ffmpeg-3.4.5.tar.bz2 (比如解压到/home/wxj/ffmpeg/ffmpeg-3.4.5)
可能需要配置ndk环境path。
4.修改ffmpeg解压目录中的 configure
使用vim 打开 configure 找到
SLIBNAME_WITH_MAJOR='$(SLIBNAME).$(LIBMAJOR)'
LIB_INSTALL_EXTRA_CMD='$$(RANLIB)"$(LIBDIR)/$(LIBNAME)"'
SLIB_INSTALL_NAME='$(SLIBNAME_WITH_VERSION)'
SLIB_INSTALL_LINKS='$(SLIBNAME_WITH_MAJOR)$(SLIBNAME)'
修改为：
SLIBNAME_WITH_MAJOR='$(SLIBPREF)$(FULLNAME)-$(LIBMAJOR)$(SLIBSUF)'
LIB_INSTALL_EXTRA_CMD='$$(RANLIB)"$(LIBDIR)/$(LIBNAME)"'
SLIB_INSTALL_NAME='$(SLIBNAME_WITH_MAJOR)'
SLIB_INSTALL_LINKS='$(SLIBNAME)'
5.在ffmpeg-3.4.5目录下新建android_build.sh脚本文件
vim android_build.sh
添加以下代码：
#!/bin/bash
make clean
export NDK=/home/wxj/ndk_build/android-ndk-r14b
export SYSROOT=$NDK/platforms/android-21/arch-arm/
export TOOLCHAIN=$NDK/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64
export CPU=armv7-a
export PREFIX=$(pwd)/android/$CPU
export ADDI_CFLAGS="-marm"
./configure \
--target-os=android \
--arch=armv7-a \
--enable-mediacodec \
--enable-decoder=h264_mediacodec \
--enable-jni \
--enable-hwaccels \
--prefix=$PREFIX \
--disable-doc \
--enable-shared \
--disable-static \
--disable-yasm \
--disable-symver \
--enable-gpl \
--enable-ffmpeg \
--disable-ffplay \
--disable-ffprobe \
--disable-ffserver \
--disable-doc \
--disable-symver \
--cross-prefix=$TOOLCHAIN/bin/arm-linux-androideabi- \
--enable-cross-compile \
--sysroot=$SYSROOT \
--extra-cflags="-Os -fpic $ADDI_CFLAGS" \
--extra-ldflags="$ADDI_LDFLAGS" \
$ADDITIONAL_CONFIGURE_FLAG
make clean
make
make install
6.赋予脚本执行权限：
chmod +x android_build.sh
执行脚本开始编译：
./android_build.sh
7.编译成功后会在 /home/wxj/ffmpeg/ffmpeg-3.4.5目录下生成一个android/armv7-a文件夹，里面有对应的so库(此时生成的so库android还不能直接使用)
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8.在ffmpeg-3.4.5目录下新建androidbuild文件夹 将步骤7 生成的obj文件夹复制过来 ，并且新建jni目录
image.png
9.此步骤可以在as中完成 新建 FFmpegNative.java
package com.sz.ffmlib;
public class FFmpegNative {
public static native void run();
}
10.生成com_sz_ffmlib_FFmpegNative.h头文件
/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class com_sz_ffmlib_FFmpegNative */
#ifndef _Included_com_sz_ffmlib_FFmpegNative
#define _Included_com_sz_ffmlib_FFmpegNative
#ifdef __cplusplus
extern "C" {
#endif
/*
* Class: com_sz_ffmlib_FFmpegNative
* Method: run
* Signature: ()V
*/
JNIEXPORT void JNICALL Java_com_sz_ffmlib_FFmpegNative_run
(JNIEnv *, jclass);
#ifdef __cplusplus
}
#endif
#endif
11.写上Android.mk以及Application.mk
Android.mk:
```
LOCAL_PATH:= $(call my-dir)
INCLUDE_PATH:=/home/wxj/ffmpeg/ffmpeg-3.4.5/android/armv7-a/include
FFMPEG_LIB_PATH:=/home/wxj/ffmpeg/ffmpeg-3.4.5/android/armv7-a/lib
include $(CLEAR_VARS)
LOCAL_MODULE:= libavcodec
LOCAL_SRC_FILES:= $(FFMPEG_LIB_PATH)/libavcodec.so
LOCAL_EXPORT_C_INCLUDES := $(INCLUDE_PATH)
include $(PREBUILT_SHARED_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE:= libavformat
LOCAL_SRC_FILES:= $(FFMPEG_LIB_PATH)/libavformat.so
LOCAL_EXPORT_C_INCLUDES := $(INCLUDE_PATH)
include $(PREBUILT_SHARED_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE:= libswscale
LOCAL_SRC_FILES:= $(FFMPEG_LIB_PATH)/libswscale.so
LOCAL_EXPORT_C_INCLUDES := $(INCLUDE_PATH)
include $(PREBUILT_SHARED_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE:= libavutil
LOCAL_SRC_FILES:= $(FFMPEG_LIB_PATH)/libavutil.so
LOCAL_EXPORT_C_INCLUDES := $(INCLUDE_PATH)
include $(PREBUILT_SHARED_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE:= libavfilter
LOCAL_SRC_FILES:= $(FFMPEG_LIB_PATH)/libavfilter.so
LOCAL_EXPORT_C_INCLUDES := $(INCLUDE_PATH)
include $(PREBUILT_SHARED_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE:= libswresample
LOCAL_SRC_FILES:= $(FFMPEG_LIB_PATH)/libswresample.so
LOCAL_EXPORT_C_INCLUDES := $(INCLUDE_PATH)
include $(PREBUILT_SHARED_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE:= libpostproc
LOCAL_SRC_FILES:= $(FFMPEG_LIB_PATH)/libpostproc.so
LOCAL_EXPORT_C_INCLUDES := $(INCLUDE_PATH)
include $(PREBUILT_SHARED_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE:= libavdevice
LOCAL_SRC_FILES:= $(FFMPEG_LIB_PATH)/libavdevice.so
LOCAL_EXPORT_C_INCLUDES := $(INCLUDE_PATH)
include $(PREBUILT_SHARED_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := ffmpeg
LOCAL_SRC_FILES := com_sz_ffmlib_FFmpegNative.c
LOCAL_C_INCLUDES := /home/wxj/ffmpeg/ffmpeg-3.4.5
LOCAL_LDLIBS := -lm -llog
LOCAL_SHARED_LIBRARIES := libavcodec libavfilter libavformat libavutil libswresample libswscale libavdevice
include $(BUILD_SHARED_LIBRARY)
```
Application.mk：
APP_ABI := armeabi-v7a
APP_PLATFORM= android-14
12.实现.h文件的具体逻辑 com_sz_ffmlib_FFmpegNative.c（测试）
#include <android/log.h>
#include "com_sz_ffmlib_FFmpegNative.h"
#include <stdlib.h>
#include <stdbool.h>
#include <stdio.h>
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libavfilter/avfilter.h"
JNIEXPORT void JNICALL Java_com_sz_ffmlib_FFmpegNative_run(JNIEnv *env, jclass obj) {
char info[40000] = {0};
av_register_all();
AVCodec *c_temp = av_codec_next(NULL);
while(c_temp != NULL){
if(c_temp->decode!=NULL){
sprintf(info,"%s[Dec]",info);
}else{
sprintf(info,"%s[Enc]",info);
}
switch(c_temp->type){
case AVMEDIA_TYPE_VIDEO:
sprintf(info,"%s[Video]",info);
break;
case AVMEDIA_TYPE_AUDIO:
sprintf(info,"%s[Audio]",info);
break;
default:
sprintf(info,"%s[Other]",info);
break;
}
sprintf(info,"%s[%10s]\n",info,c_temp->name);
c_temp=c_temp->next;
}
__android_log_print(ANDROID_LOG_INFO,"myTag","info:\n%s",info);
}
13.在jni 目录下运行ndk-build脚本命令就可以生成动态库了 生成的动态库在jni/libs/armeabi-v7a下
image.png
14.将生成的so放到项目的jniLibs里面
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调用：
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