Android多媒体开发（3）————使用Android NKD编译havlenapetr-FFMpeg-7c27aa2

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1、

使用NDK去编译官方的FFmpeg原版的话，还得自己实现JNI层与java层，工程量比较大。所以移植FFmpeg到Android平台时，可以移植一些已经实现JNI与JAVA层的开源项目，毕竟软件行业从来都是站在巨人肩膀上发展的。

2、移植havlenapetr/FFMpeg

havlenapetr的开源项目是比较出名的一个FFmpeg工程，很多Android多媒体项目都是在此基础上面修改的。

下载地址：https://github.com/havlenapetr/FFMpeg

可以直接ZIP包：https://github.com/havlenapetr/FFMpeg/zipball/debug

或者通过git方式下载，新建一个目录，然后在linux的终端下执行，当然了，你要事情安装git的相关工具

git clone https://github.com/havlenapetr/FFMpeg.git

3、利用NDK编译生成so库

下载后直接在havlenapetr-FFMpeg-7c27aa2的顶级目录下执行

$ndk/ndk-build

是可以编译通过的，不会提示任何error。

关于如何利用NDK编译，可以参考我之前的博文：http://blog.csdn.net/conowen/article/details/7518870

4、导入java工程，实现播放

然后把在eclipse里面，把havlenapetr-FFMpeg-7c27aa2这个项目import进来，就可以播放视频了。

4.1、需要注意的是：这个版本的havlenapetr FFmpeg工程只能在Android 2.2上面运行，因为havlenapetr采用的是音视频直接在JNI层输入。可以注意到havlenapetr-FFMpeg-7c27aa2目录下有prebuilt这样一个目录，此目录下有Android 2.2版本的libjniaudio.so和libjnivideo.so两个库文件。

4.2、Android版本不同导致不能播放：

havlenapetr的FFmpeg项目音视频输出如下

音频：采用Android底层的audiotrack输出。

视频：在FFmpeg解码之后，得到YUV信号，然后转换成RGB信号，最终通过Android底层的surface输出。

提示：可以移植SDL开源库实现音视频输出，因为SDL的视频输出机制是通过OPenGL呈现画面，这样就可以兼容所有的Android平台。

但是问题就来了，Android每个版本的framework都是不大一样的，所以要在底层使用Android的audiotrack和surface来输入音视频信号，就要在相应版本的Android源代码中，重新编译生成libjniaudio.so和libjnivideo.so两个库文件了。

5、编译havlenapetr FFmpeg工程Android 2.3版本的libjniaudio.so和libjnivideo.so

首先要明白一点，Android的官方源代码编译之后，是不会生成libjniaudio.so和libjnivideo.so的。所以要自己添加audiotrack.cpp、surface.cpp和Android.mk文件到Android源代码里面编译生成。（每次编译libjniaudio.so和libjnivideo.so都要重新编译这个Android源代码，时间比较长。）

5.1下载audio与video文件夹

可以在https://github.com/havlenapetr/android_frameworks_base下载audiotrack.cpp、surface.cpp和Android.mk，注意要选择正确的branch（分支）

froyo---->Android 2.2

gingerbread---->Android 2.3

ICS---->Android 4.0

5.2、编译Android系统源代码

下载之后，然后找到里面的native文件夹，把里面的audio和video文件夹拖进Android源代码的frameworks/base/native目录下。

需要注意的一点是：

gingerbread下载之后，里面是没有audio和video文件夹的，但是可以用froyo版本的audio和video文件夹。（也就是下载gingerbread感觉也没啥用Orz~~~）

但是我们可以使用froyo的audio和video文件夹，编译Android源代码是可以成功通过的，ndk-build也可以通过，但是在Android的java工程里面使用就会有以下错误信息。

java.lang.NoSuchFieldError: no field with name='mSurface' signature='I' in class Landroid/view/Surface;

加载库时，找不到mSruface类
修改方法是：
将surface.cpp中mSurface改为 mNativeSurface ,然后重新编译即可。当然了，你也可以用ICS的surface.cpp文件，这个版本是没有问题的。

另外编译havlenapetr FFmpeg工程Android 4.0版本的libjniaudio.so和libjnivideo.so与上面步骤差不多。

/************************************************************************/

附上我所使用的audio与video(来源havlenapetr的项目)

video/jni/surface.cpp(注意目录结构)

/*
 * Copyright (C) 2012 Havlena Petr
 *
 * 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.
 */

#define LOG_TAG "ASurface"
#include <utils/Log.h>

#include <surfaceflinger/Surface.h>

#include <SkCanvas.h>
#include <SkBitmap.h>
#include <SkMatrix.h>
#include <SkRect.h>

#include "surface.h"

#define CHECK(val) \
    if(!val) { \
        LOGE("%s [%i]: NULL pointer exception!", __func__, __LINE__); \
        return -1; \
    }

#define SDK_VERSION_FROYO 8

using namespace android;

typedef struct ASurface {
    /* our private members here */
    Surface* surface;
    SkCanvas canvas;
} ASurface;

static Surface* getNativeSurface(JNIEnv* env, jobject jsurface, int sdkVersion) {
    /* we know jsurface is a valid local ref, so use it */
    jclass clazz = env->GetObjectClass(jsurface);
    if(clazz == NULL) {
        LOGE("Can't find surface class!");
        return NULL;
    }

    jfieldID field_surface = env->GetFieldID(clazz,
                                             sdkVersion > SDK_VERSION_FROYO ? "mNativeSurface" : "mSurface",
                                             "I");
    if(field_surface == NULL) {
        LOGE("Can't find native surface field!");
        return NULL;
    }
    return (Surface *) env->GetIntField(jsurface, field_surface);
}

int ASurface_init(JNIEnv* env, jobject jsurface, int sdkVersion, ASurface** aSurface) {
    if(!env || jsurface == NULL) {
        LOGE("JNIEnv or jsurface obj is NULL!");
        return -1;
    }

    Surface* surface = getNativeSurface(env, jsurface, sdkVersion);
    if(!surface) {
        LOGE("Can't obtain native surface!");
        return -1;
    }

    *aSurface = (ASurface *) malloc(sizeof(ASurface));
    (*aSurface)->surface = surface;
    return 0;
}

void ASurface_deinit(ASurface** aSurface) {
    free(*aSurface);
    *aSurface = NULL;
}

int ASurface_lock(ASurface* aSurface, AndroidSurfaceInfo* info) {
    static Surface::SurfaceInfo surfaceInfo;

    CHECK(aSurface);
    CHECK(aSurface->surface);

    Surface* surface = aSurface->surface;
    if (!surface->isValid()) {
        LOGE("Native surface isn't valid!");
        return -1;
    }

    int res = surface->lock(&surfaceInfo);
    if(res < 0) {
        LOGE("Can't lock native surface!");
        return res;
    }

    info->w = surfaceInfo.w;
    info->h = surfaceInfo.h;
    info->s = surfaceInfo.s;
    info->usage = surfaceInfo.usage;
    info->format = surfaceInfo.format;
    info->bits = surfaceInfo.bits;

    return 0;
}

static SkBitmap::Config
convertPixelFormat(APixelFormat format) {
    switch(format) {
        case ANDROID_PIXEL_FORMAT_RGBX_8888:
        case ANDROID_PIXEL_FORMAT_RGBA_8888:
            return SkBitmap::kARGB_8888_Config;
        case ANDROID_PIXEL_FORMAT_RGB_565:
            return SkBitmap::kRGB_565_Config;
    }
    return SkBitmap::kNo_Config;
}

static void
initBitmap(SkBitmap& bitmap, AndroidSurfaceInfo* info) {
    bitmap.setConfig(convertPixelFormat(info->format), info->w, info->h);
    if (info->format == ANDROID_PIXEL_FORMAT_RGBX_8888) {
        bitmap.setIsOpaque(true);
    }
    if (info->w > 0 && info->h > 0) {
        bitmap.setPixels(info->bits);
    } else {
        // be safe with an empty bitmap.
        bitmap.setPixels(NULL);
    }
}

void ASurface_scaleToFullScreen(ASurface* aSurface, AndroidSurfaceInfo* src, AndroidSurfaceInfo* dst) {
    SkBitmap    srcBitmap;
    SkBitmap    dstBitmap;
    SkMatrix    matrix;

    initBitmap(srcBitmap, src);
    initBitmap(dstBitmap, dst);
    matrix.setRectToRect(SkRect::MakeWH(srcBitmap.width(), srcBitmap.height()),
                         SkRect::MakeWH(dstBitmap.width(), dstBitmap.height()),
                         SkMatrix::kFill_ScaleToFit);

    aSurface->canvas.setBitmapDevice(dstBitmap);
    aSurface->canvas.drawBitmapMatrix(srcBitmap, matrix);
}

int ASurface_rotate(ASurface* aSurface, AndroidSurfaceInfo* src, uint32_t degrees) {
    SkBitmap    bitmap;

    CHECK(aSurface);
    CHECK(src);

    initBitmap(bitmap, src);
    aSurface->canvas.setBitmapDevice(bitmap);
    return aSurface->canvas.rotate(SkScalar(degrees)) ? 0 : -1;
}

int ASurface_unlockAndPost(ASurface* aSurface) {
    CHECK(aSurface);
    CHECK(aSurface->surface);
    return aSurface->surface->unlockAndPost();
}

video/jni/Android.mk(注意目录结构)

LOCAL_PATH:= $(call my-dir)
include $(CLEAR_VARS)

# our source files
#
LOCAL_SRC_FILES:= \
	surface.cpp

LOCAL_SHARED_LIBRARIES := \
	libskia \
    	libsurfaceflinger_client \
    	libutils \
	liblog

LOCAL_C_INCLUDES += \
	$(JNI_H_INCLUDE) \
	external/skia/src/core \
	external/skia/include/core \
	frameworks/base/include \
	frameworks/base/native/include

# Optional tag would mean it doesn't get installed by default
LOCAL_MODULE_TAGS := optional

LOCAL_PRELINK_MODULE := false

LOCAL_MODULE:= libjnivideo

include $(BUILD_SHARED_LIBRARY)

/audio/jni/audiotrack.cpp(注意目录结构)

/*
 * 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 <android/audiotrack.h>
#include <utils/Log.h>
#include <media/AudioTrack.h>
#include <media/AudioSystem.h>
#include <utils/Errors.h>

#include <binder/MemoryHeapBase.h>
#include <binder/MemoryBase.h>

#define TAG "AudioTrackWrapper"

using namespace android;

//struct audiotrack_fields_t {
static AudioTrack*						track;
//sp<MemoryHeapBase>					memHeap;
//sp<MemoryBase>						memBase;
//};
//static struct audiotrack_fields_t audio;

static AudioTrack* getNativeAudioTrack(JNIEnv* env, jobject jaudioTrack) {
	jclass clazz = env->FindClass("android/media/AudioTrack");
	jfieldID field_track = env->GetFieldID(clazz, "mNativeTrackInJavaObj", "I");
	if(field_track == NULL) {
		return NULL;
	}
	return (AudioTrack *) env->GetIntField(jaudioTrack, field_track);
}

/*
static bool allocSharedMem(int sizeInBytes) {
	memHeap = new MemoryHeapBase(sizeInBytes);
	if (memHeap->getHeapID() < 0) {
		return false;
	}
	memBase = new MemoryBase(memHeap, 0, sizeInBytes);
	return true;
}
*/

int AndroidAudioTrack_register() {
	__android_log_print(ANDROID_LOG_INFO, TAG, "registering audio track");
	track = new AudioTrack();
	if(track == NULL) {
	     return ANDROID_AUDIOTRACK_RESULT_JNI_EXCEPTION;
	}
	__android_log_print(ANDROID_LOG_INFO, TAG, "registered");
	return ANDROID_AUDIOTRACK_RESULT_SUCCESS;
}

int AndroidAudioTrack_start() {
	//__android_log_print(ANDROID_LOG_INFO, TAG, "starting audio track");
    if(track == NULL) {
        return ANDROID_AUDIOTRACK_RESULT_ALLOCATION_FAILED;
    }
	track->start();
    return ANDROID_AUDIOTRACK_RESULT_SUCCESS;
}

int AndroidAudioTrack_set(int streamType,
						  uint32_t sampleRate,
						  int format,
						  int channels) {
	if(track == NULL) {
        return ANDROID_AUDIOTRACK_RESULT_ALLOCATION_FAILED;
    }
	
	__android_log_print(ANDROID_LOG_INFO, TAG, "setting audio track");
	
	status_t ret = track->set(streamType, 
							  sampleRate, 
							  format, 
							  channels, 
							  0, 
							  0,
							  0, 
							  0,
							  false);
	
	if (ret != NO_ERROR) {
		return ANDROID_AUDIOTRACK_RESULT_ERRNO;
	}
	return ANDROID_AUDIOTRACK_RESULT_SUCCESS;
}

int AndroidAudioTrack_flush() {
    if(track == NULL) {
        return ANDROID_AUDIOTRACK_RESULT_ALLOCATION_FAILED;
    }
	track->flush();
    return ANDROID_AUDIOTRACK_RESULT_SUCCESS;
}

int AndroidAudioTrack_stop() {
    if(track == NULL) {
        return ANDROID_AUDIOTRACK_RESULT_ALLOCATION_FAILED;
    }
	track->stop();
    return ANDROID_AUDIOTRACK_RESULT_SUCCESS;
}

int AndroidAudioTrack_reload() {
    if(track == NULL) {
        return ANDROID_AUDIOTRACK_RESULT_ALLOCATION_FAILED;
    }
	if(track->reload() != NO_ERROR) {
		return ANDROID_AUDIOTRACK_RESULT_ERRNO;
	}
    return ANDROID_AUDIOTRACK_RESULT_SUCCESS;
}

int AndroidAudioTrack_unregister() {
	__android_log_print(ANDROID_LOG_INFO, TAG, "unregistering audio track");
    if(!track->stopped()) {
        track->stop();
    }
	//memBase.clear();
	//memHeap.clear();
	free(track);
	//track = NULL;
	__android_log_print(ANDROID_LOG_INFO, TAG, "unregistered");
    return ANDROID_AUDIOTRACK_RESULT_SUCCESS;
}

int AndroidAudioTrack_write(void *buffer, int buffer_size) {
	// give the data to the native AudioTrack object (the data starts at the offset)
    ssize_t written = 0;
    // regular write() or copy the data to the AudioTrack's shared memory?
    if (track->sharedBuffer() == 0) {
        written = track->write(buffer, buffer_size);
    } else {
		// writing to shared memory, check for capacity
		if ((size_t)buffer_size > track->sharedBuffer()->size()) {
			__android_log_print(ANDROID_LOG_INFO, TAG, "buffer size was too small");
			buffer_size = track->sharedBuffer()->size();
		}
		memcpy(track->sharedBuffer()->pointer(), buffer, buffer_size);
		written = buffer_size;
	}
	return written;
}

/audio/jni/Android.mk(注意目录结构)

LOCAL_PATH:= $(call my-dir)
include $(CLEAR_VARS)

# our source files
#
LOCAL_SRC_FILES:= \
	audiotrack.cpp

LOCAL_SHARED_LIBRARIES := \
	libbinder \
    	libmedia \
    	libutils \
	liblog

LOCAL_C_INCLUDES += \
	$(JNI_H_INCLUDE) \
	frameworks/base/include \
	frameworks/base/native/include

# Optional tag would mean it doesn't get installed by default
LOCAL_MODULE_TAGS := optional

LOCAL_PRELINK_MODULE := false

LOCAL_MODULE:= libjniaudio

include $(BUILD_SHARED_LIBRARY)

评论

1 楼 light-chen 2012-05-30  

你好,很感謝你分享這麼有用的心得文,我這2天將havlenapetr/FFMPEG 的source抓下來,用 ndk r6去直接編譯他,
邊玩正常會在libs/armeabi/ 下也出現 libffmpeg_jni.so ,libjniaudio.so,libjnivideo.so

之後也將 android 2.2 導入進去成一可執行的專案檔,但執行的過程中,選擇要撥放的影片後,在DDMS下的log會出現

05-30 04:32:20.783: D/dalvikvm(31073): Trying to load lib /data/data/cz.havlena.ffmpeg.ui/lib/libjniaudio.so 0x40d23dd8
05-30 04:32:20.783: D/FFMpeg(31073): Couldn't load lib: jniaudio - Cannot load library: find_library[1204]: 140 'libjniaudio.so' failed to load previously
05-30 04:32:20.783: D/dalvikvm(31073): Trying to load lib /data/data/cz.havlena.ffmpeg.ui/lib/libjnivideo.so 0x40d23dd8
05-30 04:32:20.783: D/FFMpeg(31073): Couldn't load lib: jnivideo - Cannot load library: find_library[1204]: 140 'libjnivideo.so' failed to load previously
05-30 04:32:20.783: D/dalvikvm(31073): Trying to load lib /data/data/cz.havlena.ffmpeg.ui/lib/libffmpeg_jni.so 0x40d23dd8
05-30 04:32:20.783: D/FFMpeg(31073): Couldn't load lib: ffmpeg_jni - Cannot load library: find_library[1204]: 140 'libffmpeg_jni.so' failed to load previously
05-30 04:32:20.783: D/FFMpegPlayerActivity(31073): Error when inicializing ffmpeg: Couldn't load native libs


我想主要就是一開始連load lib都進不來
Couldn't load lib libjniaudio.so,libjnivideo.so,libffmpeg_jni.so

不知道是甚麼問題,不是原本這專案編譯完後,在android 2.2下是可以正常執行嗎?

非常感謝你