本篇文章来介绍如何封装JNI解码库接口，然后编译出可以直接使用的so文件
编译环境请参考 二、编译ffmpeg
1.在android-ndk-r9d/samples中新建文件夹demo2,在demo2中新建jni文件夹，jni中新建arm文件夹，将之前我们编译好的ffmpeg动态库和头文件复制到arm文件夹中,如下图
2.编写ALog.h，用于在调试过程中打印信息
#include
#define ALOGI(fmt,args...) __android_log_print(ANDROID_LOG_INFO, LOG_TAG, fmt, ##args)
#define ALOGD(fmt,args...) __android_log_print(ANDROID_LOG_DEBUG, LOG_TAG, fmt, ##args)
#define ALOGE(fmt,args...) __android_log_print(ANDROID_LOG_ERROR, LOG_TAG, fmt, ##args)
3.编写H264Decoder.c,在java中定义的包名必须为com.decoder.util,类名为DecH264,方法名和下面代码中的方法名保持一致
#include
#include
#include
#include
#include
#include
#define LOG_TAG "H264Decoder.c"
//解码
struct AVCodecContext *pAVCodecCtx;
struct AVCodec *pAVCodec;
//输入数据变量
struct AVPacket mAVPacket;
//输出变量
struct AVFrame *pAVFrame;
//分辨率长宽
int iWidth = 0;
int iHeight = 0;
//初始化
jint Java_com_decoder_util_DecH264_InitDecoder(JNIEnv* env, jobject thiz)
{
av_register_all();
pAVCodec = avcodec_find_decoder(CODEC_ID_H264);
if (pAVCodec == NULL)
{
return -1;
}
pAVCodecCtx = avcodec_alloc_context3(pAVCodec);
if (pAVCodecCtx == NULL)
{
return -1;
}
//设置解码时是否是完整帧
// if (pAVCodecCtx->capabilites & CODEC_CAP_TRUNCATED)
// {
// pAVCodecCtx->flags |= CODEC_CAP_TRUNCATED;
// }
if (avcodec_open2(pAVCodecCtx, pAVCodec, NULL) < 0)
{
return -1;
}
av_init_packet(&mAVPacket);
pAVFrame = av_frame_alloc();
if (pAVFrame == NULL)
{
return -1;
}
return 0;
}
//释放资源
jint Java_com_decoder_util_DecH264_UnInitDecoder(JNIEnv* env, jobject thiz)
{
iWidth = 0;
iHeight = 0;
if (pAVCodecCtx != NULL)
{
avcodec_close(pAVCodecCtx);
pAVCodecCtx = NULL;
}
if (pAVFrame != NULL)
{
av_free(pAVFrame);
pAVFrame = NULL;
}
return 0;
}
//解码函数
jint Java_com_decoder_util_DecH264_DecoderNal(JNIEnv* env, jobject thiz,
jbyteArray in, jint nalLen, jintArray prama, jbyteArray out)
{
int len = -1, got_picture = 0;
jbyte* inbuf = (*env)->GetByteArrayElements(env, in, 0);
jint* outPrama = (jint*)(*env)->GetIntArrayElements(env, prama, 0);
jbyte* picture = (*env)->GetByteArrayElements(env, out, 0);
mAVPacket.data = inbuf;
mAVPacket.size = nalLen;
len = avcodec_decode_video2(pAVCodecCtx, pAVFrame, &got_picture, &mAVPacket);
if (got_picture)
{
//如果在传输的过程中视频的分辨率发生变化 则需要告诉解码后的数据当前帧的分辨率
if ((pAVCodecCtx->width != iWidth) || (pAVCodecCtx->height != iHeight))
{
iWidth = pAVCodecCtx->width;
iHeight = pAVCodecCtx->height;
}
//取视频帧
int i, j, nshift, nBufPtr = 0;
uint8_t* yuv_factor;
for (i = 0; i < 3; i++)
{
nshift = (i == 0 ? 0 : 1);
yuv_factor = pAVFrame->data[i];
for (j = 0; i < pAVCodecCtx->height>>nshift; j++)
{
memcpy((char*)picture + nBufPtr, yuv_factor, pAVCodecCtx->width>>nshift);
yuv_factor += pAVFrame->linesize[i];
nBufPtr += pAVCodecCtx->width>>nshift;
}
}
// 保存 W H
outPrama[2] = pAVCodecCtx->width;
outPrama[3] = pAVCodecCtx->height;
}
else{
len = 1;
}
(*env)->ReleaseByteArrayElements(env, in, inbuf,0);
(*env)->ReleaseIntArrayElements(env, prama, outPrama,0);
(*env)->ReleaseByteArrayElements(env, out, picture,0);
return 0;
}
4.编写Android.mk文件,如果你的文件路径和我不一样，请将LOCAL_SRC_FILES和LOCAL_C_INCLUDES中的路径更换为你自己的路径，否则会编译出错
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := avcodec
LOCAL_SRC_FILES := arm/lib/libavcodec.so
include $(PREBUILT_SHARED_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := avformat
LOCAL_SRC_FILES := arm/lib/libavformat.so
include $(PREBUILT_SHARED_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := avutil
LOCAL_SRC_FILES := arm/lib/libavutil.so
include $(PREBUILT_SHARED_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := avfilter
LOCAL_SRC_FILES := arm/lib/libavfilter.so
include $(PREBUILT_SHARED_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := swresample
LOCAL_SRC_FILES := arm/lib/libswresample.so
include $(PREBUILT_SHARED_LIBRARY)
include $(CLEAR_VARS)
LOCAL_MODULE := swscale
LOCAL_SRC_FILES := arm/lib/libswscale.so
include $(PREBUILT_SHARED_LIBRARY)
include $(CLEAR_VARS)
LOCAL_SRC_FILES := H264Decoder.c 需要编译的源文件
LOCAL_MODULE := H264Decoder-yuv 编译后生成的动态库名称
LOCAL_C_INCLUDES += $(LOCAL_PATH)/arm/include \
$(LOCAL_PATH)/arm/include/libavcodec \
$(LOCAL_PATH)/arm/include/libavformat \
$(LOCAL_PATH)/arm/include/libavutil \
$(LOCAL_PATH)/arm/include/libavfilter \
$(LOCAL_PATH)/arm/include/libswresample \
$(LOCAL_PATH)/arm/include/libswscale \
LOCAL_LDLIBS := -L$(NDK_PLATFORMS_ROOT)/$(TARGET_PLATFORM)/arch-arm/usr \
-L$(LOCAL_PATH)/arm/lib -lavformat -lavcodec -lavfilter -lavutil -lswscale -lswresample \
-llog -lz -ldl
LOCAL_LDLIBS += -lGLESv2
LOCAL_LDLIBS += -lm
LOCAL_SHARED_LIBRARIES += \
libcutils libutils
include $(BUILD_SHARED_LIBRARY)
5.编写Application.mk文件
# APP_ABI := all
# APP_ABI := armeabi-v7a x86
# APP_ABI := armeabi x86
# APP_ABI := armeabi armeabi-v7a x86
APP_ABI := armeabi
APP_PLATFORM := android-15
6.最后在jni目录下，输入ndk-build，如果没有错误的话，恭喜你，就可以正确编译出libH264Decoder-yuv.so了，编译生成的库在demo2/libs/armeabi中
需要完整代码和库文件请戳下面链接
https://download.csdn.net/download/adolph_lu/10467443