ffmpeg移植android及应用
搞这东西集合了好多人的东西，单照一个人的做老出错，弄了几天终于出来了，把遇到的问题都写了下来
讲讲编译的步骤：
1. 安装cygwin
必须是1.7或者更新的版本
安装cygwin的时候，选择安装gcc和make，目的是为了提供编译环境，
make的版本至少是3.81
2.安装ndk
· 2.1 下载ndk-r4b-windows，并将其放到cygwin的/home/Administator目录
· 设置环境变量
将/etc/skel/目录的 .bash_profile .bashrc .inputrc拷贝到/home/administrator目录，
编辑/home/administrator目录的 .bashrc文件，在后面增加两行：
NDK_ROOT=~/android-ndk-r4b/
export NDK_ROOT
~的实际目录是cygwin的/home/
Administrator目录
3.下载ffmpeg
版本是0.6.1
在android-ndk-r4b/samples目录，创建文件夹FFMPEG，在ffmpeg目录创建jni目录，
将ffmpeg解压并将全部源码拷贝到jni目录
ffmpeg源码的路径变成：
~ /android-ndk-r4b/samples/FFMPEG/jni/ffmpeg
4.编译准备
· cd到ffmpeg目录，执行dos2unix configure，转换文件格式
· 在ffmpeg源码目录新建config.sh，并转换成 unix格式,
内容如下：
#!/bin/bash
export TMPDIR="c:/temp/android"
export NDKROOT="C:/cygwin/home/Administrator/android-ndk-r4b"
PREBUILT=$NDKROOT/build/prebuilt/windows/arm-eabi-4.4.0
PLATFORM=$NDKROOT/build/platforms/android-8/arch-arm
./configure --target-os=linux \
--arch=arm \
--enable-version3 \
--enable-gpl \
--enable-nonfree \
--disable-stripping \
--disable-ffmpeg \
--disable-ffplay \
--disable-ffserver \
--disable-ffprobe \
--disable-encoders \
--disable-muxers \
--disable-devices \
--disable-protocols \
--enable-protocol=file \
--enable-avfilter \
--disable-network \
--disable-mpegaudio-hp \
--disable-avdevice \
--enable-cross-compile \
--cc=$PREBUILT/bin/arm-eabi-gcc \
--cross-prefix=$PREBUILT/bin/arm-eabi- \
--nm=$PREBUILT/bin/arm-eabi-nm \
--extra-cflags="-fPIC -DANDROID" \
--disable-asm \
--enable-neon \
--enable-armv5te \
--extra-ldflags="-Wl,-T,$PREBUILT/arm-eabi/lib/ldscripts/armelf.x -Wl,-rpath-link=$PLATFORM/usr/lib -L$PLATFORM/usr/lib -nostdlib $PREBUILT/lib/gcc/arm-eabi/4.4.0/crtbegin.o $PREBUILT/lib/gcc/arm-eabi/4.4.0/crtend.o -lc -lm -ldl"
执行： chmod +x config.sh && ./config.sh
输出：creating config.mak and config.h...
执行成功
· 修改生成的config.h，将其中的
#define restrict restrict改成 #define restrict
转换文件格式
· 编辑libavutil/libm.h，将其中的所有static方法删除
转换文件格式
· 修改libavcodec,libavfilter,libavformat,libavutil,libpostproc和libswscale目录的MakeFile文件，
将以下内容删除：
include $( SUBDIR ) ../config.mak
include $ (SUBDIR) .. / subdir.mak
修改之后转换文件格式
· 在ffmpeg源码目录新建av.mk文件
内容如下：
# LOCAL_PATH is one of libavutil, libavcodec, libavformat, or libswscale
#include $(LOCAL_PATH)/../config-$(TARGET_ARCH).mak
include $(LOCAL_PATH)/../config.mak
OBJS :=
OBJS-yes :=
MMX-OBJS-yes :=
include $(LOCAL_PATH)/Makefile
# collect objects
OBJS-$(HAVE_MMX) += $(MMX-OBJS-yes)
OBJS += $(OBJS-yes)
FFNAME := lib$(NAME)
FFLIBS := $(foreach,NAME,$(FFLIBS),lib$(NAME))
FFCFLAGS = -DHAVE_AV_CONFIG_H -Wno-sign-compare -Wno-switch -Wno-pointer-sign
FFCFLAGS += -DTARGET_CONFIG=\"config-$(TARGET_ARCH).h\"
ALL_S_FILES := $(wildcard $(LOCAL_PATH)/$(TARGET_ARCH)/*.S)
ALL_S_FILES := $(addprefix $(TARGET_ARCH)/, $(notdir $(ALL_S_FILES)))
ifneq ($(ALL_S_FILES),)
ALL_S_OBJS := $(patsubst %.S,%.o,$(ALL_S_FILES))
C_OBJS := $(filter-out $(ALL_S_OBJS),$(OBJS))
S_OBJS := $(filter $(ALL_S_OBJS),$(OBJS))
else
C_OBJS := $(OBJS)
S_OBJS :=
endif
C_FILES := $(patsubst %.o,%.c,$(C_OBJS))
S_FILES := $(patsubst %.o,%.S,$(S_OBJS))
FFFILES := $(sort $(S_FILES)) $(sort $(C_FILES))
创建一系列Android.mk文件
在jni目录，创建Android.mk，内容如下：
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_WHOLE_STATIC_LIBRARIES := libavformat libavcodec libavutil libpostproc libswscale
LOCAL_MODULE := ffmpeg
include $(BUILD_SHARED_LIBRARY)
include $(call all-makefiles-under,$(LOCAL_PATH))
在libavformat/目录，创建Android.mk，文件如下：
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
include $(LOCAL_PATH)/../av.mk
LOCAL_SRC_FILES := $(FFFILES)
LOCAL_C_INCLUDES := \
$(LOCAL_PATH) \
$(LOCAL_PATH)/..
LOCAL_CFLAGS += $(FFCFLAGS)
LOCAL_CFLAGS += -include "string.h" -Dipv6mr_interface=ipv6mr_ifindex
LOCAL_LDLIBS := -lz
LOCAL_STATIC_LIBRARIES := $(FFLIBS)
LOCAL_MODULE := $(FFNAME)
include $(BUILD_STATIC_LIBRARY)
在libavcodec/目录，创建Android.mk，文件如下：
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
include $(LOCAL_PATH)/../av.mk
LOCAL_SRC_FILES := $(FFFILES)
LOCAL_C_INCLUDES := \
$(LOCAL_PATH) \
$(LOCAL_PATH)/..
LOCAL_CFLAGS += $(FFCFLAGS)
LOCAL_LDLIBS := -lz
LOCAL_STATIC_LIBRARIES := $(FFLIBS)
LOCAL_MODULE := $(FFNAME)
include $(BUILD_STATIC_LIBRARY)
在libavfilter创建Android.mk，文件如下：
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
include $(LOCAL_PATH)/../av.mk
LOCAL_SRC_FILES := $(FFFILES)
LOCAL_C_INCLUDES := \
$(LOCAL_PATH) \
$(LOCAL_PATH)/..
LOCAL_CFLAGS += $(FFCFLAGS)
LOCAL_STATIC_LIBRARIES := $(FFLIBS)
LOCAL_MODULE := $(FFNAME)
include $(BUILD_STATIC_LIBRARY)
在libavutil创建Android.mk，文件如下：
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
include $(LOCAL_PATH)/../av.mk
LOCAL_SRC_FILES := $(FFFILES)
LOCAL_C_INCLUDES := \
$(LOCAL_PATH) \
$(LOCAL_PATH)/..
LOCAL_CFLAGS += $(FFCFLAGS)
LOCAL_STATIC_LIBRARIES := $(FFLIBS)
LOCAL_MODULE := $(FFNAME)
include $(BUILD_STATIC_LIBRARY)
在libpostproc创建Android.mk，文件如下：
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
include $(LOCAL_PATH)/../av.mk
LOCAL_SRC_FILES := $(FFFILES)
LOCAL_C_INCLUDES := \
$(LOCAL_PATH) \
$(LOCAL_PATH)/..
LOCAL_CFLAGS += $(FFCFLAGS)
LOCAL_STATIC_LIBRARIES := $(FFLIBS)
LOCAL_MODULE := $(FFNAME)
include $(BUILD_STATIC_LIBRARY)
在libswscale目录，创建Android.mk，文件如下：
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
include $(LOCAL_PATH)/../av.mk
LOCAL_SRC_FILES := $(FFFILES)
LOCAL_C_INCLUDES := \
$(LOCAL_PATH) \
$(LOCAL_PATH)/..
LOCAL_CFLAGS += $(FFCFLAGS)
LOCAL_STATIC_LIBRARIES := $(FFLIBS)
LOCAL_MODULE := $(FFNAME)
include $(BUILD_STATIC_LIBRARY)
5.进行编译
执行： $NDK_ROOT/ndk-build NDK_PROJECT_PATH=$NDK_ROOT/samples/FFMPEG
编译成功，在生成的libs目录看到.a和.so文件
6.可能出现的错误
6.1 执行config.sh时，出现错误：
Unknown option "--target-os=linux".
See ./configure --help for available options.
解决办法：ffmpeg的版本不支持，换成0.6.1即可
6.2 执行config.sh是，出现错误：
./config.sh: line 8: --enable-nonfree: command not found
./config.sh: line 9: --disable-ffprobe: command not found
.........
解决办法：config.sh中的configure命令，后面跟的参数有换行符，导致系统认为
参数是新的命令行。将换行符删除即可
7.其他问题
编辑的文件，都要转换成unix文件格式。
在unix文件格式中， '\'可以代表空格。
8.libffmpeg文件很小是空文件问题解决
很多人在用 havlenapetr的方法编译 FFmpeg时只得到一个 1599字节 1.6KB 大小的 libffmpeg.so 文件，无论是用 Android NDK r4b编译还是用 Android NDK r5编译结果都是如此，很让人抓狂。我也很郁闷，最后花时间研究了一下 NDK，终于发现了解决方法，而且 Android NDK r4b和 Android NDK r5 的情况还是完全不同的，请继续往下读。
1 使用 Android NDK r4b编译
打开 android-ndk-r4b/build/toolchains/arm-eabi-4.4.0目录中的 setup.mk文件，你会发现 Google在里面定义了一个用于编译动态库的 cmd-build-shared-library函数。在cmd-build-shared-library函数中Google 使用了 PRIVATE_WHOLE_STATIC_LIBRARIES函数。但是你在 android-ndk-r4b/build/core目录中的 build-binary.mk文件里却找不到 PRIVATE_WHOLE_STATIC_LIBRARIES函数……外？WHY？终于搞清楚了，原来得不到正确的 libffmpeg.so 文件不是我的错，而是 Android NDK r4b的 BUG！你妹啊！你大爷啊！坑爹呢这是！发布前不做测试吗！居然漏掉一个函数！！！（我敢说这是个 BUG是因为 Google 在 Android NDK r5 中修复了这个 BUG）
木办法，只好手动替 Google修补这个 BUG。好在修改方法很简单，只需要照 build-binary.mk文件里的 PRIVATE_STATIC_LIBRARIES增加一个 PRIVATE_WHOLE_STATIC_LIBRARIES就行了。具体方法见下图
修改前的 build-binary.mk文件
修改后的 build-binary.mk文件
1 使用 Android NDK r5编译
打开 android-ndk-r5/build/core目录中的 build-binary.mk文件，发现 Google这次没有忘记PRIVATE_WHOLE_STATIC_LIBRARIES，但还最后编译得到的 libffmpeg.so文件大小还是不正确。这次的问题是，android-ndk-r5默认是使用 arm-linux-androideabi-4.4.3编译，而不是 arm-eabi-4.4.0。但 android-ndk-r5/toolchains/arm-linux-androideabi-4.4.3目录中的 setup.mk文件里定义的 cmd-build-shared-library 函数并没有将静态库文件链接在一起生成动态库文件。所以解决的办法就是在执行 ndk-build时加上 NDK_TOOLCHAIN参数，指定使用 arm-eabi-4.4.0来编译。完整命令如下
/root/android-ndk-r5/ndk-build NDK_PROJECT_PATH=/root/ffmpeg NDK_TOOLCHAIN=arm-eabi-4.4.0 NDK_PLATFORM=android-8
9.编译好libffmpeg.so后，我们要怎么应用呢，如下
折腾了几天，成功的用jni调用了libffmpeg中的一个方法-----avcodec_version()，
还得编译一个so文件，这个so里的是jni方法，可以由java层调用的，而这些jni方法里用到的函数则就是来至libffmpeg.so了。思路是有了，但是具体怎么做呢？又经过一顿摸索，n次的编译，终于编译成功了。我是拿一个标准的ndk例子来做的测试就是ndk samples文件夹里的hello-jni工程。进入该工程的jni目录，将ffmpeg的源代码（就是你用来编译libffmpeg的那个增加了Android.mk的那个源码）拷到该目录下，做这部的原因是你要编译的so文件里需要调用ffmpeg的方法，自然要引用ffmpeg里的h文件，然后将libffmpeg.so文件拷到ndk目录下的platforms/android-5/arch-arm/usr/lib目录下(你会发现platfroms里有好几个android文件夹如 -3 -4 -5分别代表不同的版本，本以为只要拷其中一个就可以，可编译的时候老出错，什么找不到-lffmpeg什么错，还是要全部都拷)，因为等等系统编译的时候要用。接下来就编辑android.mk和hello-jni.c文件了 代码如下
android.mk
C代码
- # Copyright (C) 2009 The Android Open Source Project
- #
- # 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.
- #
- LOCAL_PATH := $(call my-dir)
- include $(CLEAR_VARS)
- PATH_TO_FFMPEG_SOURCE:=$(LOCAL_PATH)/ffmpeg
- LOCAL_C_INCLUDES += $(PATH_TO_FFMPEG_SOURCE)
- LOCAL_LDLIBS := -lffmpeg
- LOCAL_MODULE := hello-jni
- LOCAL_SRC_FILES := hello-jni.c
- include $(BUILD_SHARED_LIBRARY)
# Copyright (C) 2009 The Android Open Source Project
#
# 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.
#
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
PATH_TO_FFMPEG_SOURCE:=$(LOCAL_PATH)/ffmpeg
LOCAL_C_INCLUDES += $(PATH_TO_FFMPEG_SOURCE)
LOCAL_LDLIBS := -lffmpeg
LOCAL_MODULE := hello-jni
LOCAL_SRC_FILES := hello-jni.c
include $(BUILD_SHARED_LIBRARY)
PATH_TO_FFMPEG_SOURCE:=$(LOCAL_PATH)/ffmpeg
这行是定义一个变量，也就是ffmpeg源码的路径
LOCAL_C_INCLUDES += $(PATH_TO_FFMPEG_SOURCE)
这行是指定源代码的路径，也就是刚才拷过去的ffmpeg源码，$(LOCAL_PATH)是根目录，如果没有加这行那么引入ffmpeg库中的h文件编译就会出错说找不到该h文件。
LOCAL_LDLIBS := -lffmpeg
这行很重要，这是表示你这个so运行的时候依赖于libffmpeg.so这个库，再举个例子：如果你要编译的so不仅要用到libffmpeg.so这个库还要用的libopencv.so这个库的话，你这个参数就应该写成
LOCAL_LDLIBS := -lffmpeg -lopencv
其他的参数都是正常的ndk编译用的了，不明白的话google一下。
hello-jni.c
C代码
- /*
- * Copyright (C) 2009 The Android Open Source Project
- *
- * 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.
- *
- */
- #include <string.h>
- #include <stdio.h>
- #include <android/log.h>
- #include <stdlib.h>
- #include <jni.h>
- #include <ffmpeg/libavcodec/avcodec.h>
- /* This is a trivial JNI example where we use a native method
- * to return a new VM String. See the corresponding Java source
- * file located at:
- *
- * apps/samples/hello-jni/project/src/com/example/HelloJni/HelloJni.java
- */
- jstring
- Java_com_example_hellojni_HelloJni_stringFromJNI( JNIEnv* env,
- jobject thiz )
- {
- char str[25];
- sprintf(str, "%d", avcodec_version());
- return (*env)->NewStringUTF(env, str);
- }
/*
* Copyright (C) 2009 The Android Open Source Project
*
* 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.
*
*/
#include <string.h>
#include <stdio.h>
#include <android/log.h>
#include <stdlib.h>
#include <jni.h>
#include <ffmpeg/libavcodec/avcodec.h>
/* This is a trivial JNI example where we use a native method
* to return a new VM String. See the corresponding Java source
* file located at:
*
* apps/samples/hello-jni/project/src/com/example/HelloJni/HelloJni.java
*/
jstring
Java_com_example_hellojni_HelloJni_stringFromJNI( JNIEnv* env,
jobject thiz )
{
char str[25];
sprintf(str, "%d", avcodec_version());
return (*env)->NewStringUTF(env, str);
}
#include <ffmpeg/libavcodec/avcodec.h>
这行是因为下面要用到avcodec_version()这个函数。
改完这两个文件以后就可以编译了~~用ndk-build命令编译完后在工程的libs/armeabi目录底下就会有一个libhello-jni.so文件了！（两行眼泪啊~终于编译成功了）
编译完成后就可以进行测试了，记得将libffmpeg.so也拷到armeabi目录底下，并在java代码中写上
Java代码
- static {
- System.loadLibrary("ffmpeg");
- System.loadLibrary("hello-jni");
- }
static {
System.loadLibrary("ffmpeg");
System.loadLibrary("hello-jni");
}
HelloJni.java
Java代码
- /*
- * Copyright (C) 2009 The Android Open Source Project
- *
- * 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.
- */
- package com.example.hellojni;
- import android.app.Activity;
- import android.widget.TextView;
- import android.os.Bundle;
- public class HelloJni extends Activity
- {
- /** Called when the activity is first created. */
- @Override
- public void onCreate(Bundle savedInstanceState)
- {
- super.onCreate(savedInstanceState);
- /* Create a TextView and set its content.
- * the text is retrieved by calling a native
- * function.
- */
- TextView tv = new TextView(this);
- tv.setText( "1111" );
- //System.out.println();
- setContentView(tv);
- tv.setText(String.valueOf(stringFromJNI()));
- }
- /* A native method that is implemented by the
- * 'hello-jni' native library, which is packaged
- * with this application.
- */
- public native String stringFromJNI();
- /* This is another native method declaration that is *not*
- * implemented by 'hello-jni'. This is simply to show that
- * you can declare as many native methods in your Java code
- * as you want, their implementation is searched in the
- * currently loaded native libraries only the first time
- * you call them.
- *
- * Trying to call this function will result in a
- * java.lang.UnsatisfiedLinkError exception !
- */
- public native String unimplementedStringFromJNI();
- /* this is used to load the 'hello-jni' library on application
- * startup. The library has already been unpacked into
- * /data/data/com.example.HelloJni/lib/libhello-jni.so at
- * installation time by the package manager.
- */
- static {
- System.loadLibrary("ffmpeg");
- System.loadLibrary("hello-jni");
- }
- }
/*
* Copyright (C) 2009 The Android Open Source Project
*
* 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.
*/
package com.example.hellojni;
import android.app.Activity;
import android.widget.TextView;
import android.os.Bundle;
public class HelloJni extends Activity
{
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
/* Create a TextView and set its content.
* the text is retrieved by calling a native
* function.
*/
TextView tv = new TextView(this);
tv.setText( "1111" );
//System.out.println();
setContentView(tv);
tv.setText(String.valueOf(stringFromJNI()));
}
/* A native method that is implemented by the
* 'hello-jni' native library, which is packaged
* with this application.
*/
public native String stringFromJNI();
/* This is another native method declaration that is *not*
* implemented by 'hello-jni'. This is simply to show that
* you can declare as many native methods in your Java code
* as you want, their implementation is searched in the
* currently loaded native libraries only the first time
* you call them.
*
* Trying to call this function will result in a
* java.lang.UnsatisfiedLinkError exception !
*/
public native String unimplementedStringFromJNI();
/* this is used to load the 'hello-jni' library on application
* startup. The library has already been unpacked into
* /data/data/com.example.HelloJni/lib/libhello-jni.so at
* installation time by the package manager.
*/
static {
System.loadLibrary("ffmpeg");
System.loadLibrary("hello-jni");
}
}
到此就完成了，将程序装到手机可看到打印出3426306
