前一篇[原]如何用Android NDK编译FFmpeg 我们知道了如何使用NDK来编译Android平台下使用的FFmpeg动态库。这篇文章我们就可以使用Android下的JNI来调用FFMpeg进行解码了。
一、编译出来可以使用的动态库，我们会看到如下输出则表示link完成了：
CC libavcodec/log2_tab.o CC libavutil/log2_tab.o CC libswresample/log2_tab.o AR libavcodec/libavcodec.a LD libavutil/libavutil.so.52 AR libavutil/libavutil.a AR libswresample/libswresample.a LD libavcodec/libavcodec.so.55 LD libswresample/libswresample.so.0 LD libswscale/libswscale.so.2 LD libavformat/libavformat.so.55 INSTALL libavformat/libavformat.a INSTALL libavformat/libavformat.so STRIP install-libavformat-shared INSTALL libavcodec/libavcodec.a INSTALL libavcodec/libavcodec.so STRIP install-libavcodec-shared INSTALL libswresample/libswresample.a INSTALL libswresample/libswresample.so STRIP install-libswresample-shared INSTALL libswscale/libswscale.a INSTALL libswscale/libswscale.so STRIP install-libswscale-shared INSTALL libavutil/libavutil.a INSTALL libavutil/libavutil.so STRIP install-libavutil-shared INSTALL libavformat/avformat.h INSTALL libavformat/avio.h INSTALL libavformat/version.h INSTALL libavformat/libavformat.pc INSTALL libavcodec/avcodec.h INSTALL libavcodec/avfft.h INSTALL libavcodec/dxva2.h INSTALL libavcodec/old_codec_ids.h INSTALL libavcodec/vaapi.h INSTALL libavcodec/vda.h INSTALL libavcodec/vdpau.h INSTALL libavcodec/version.h INSTALL libavcodec/xvmc.h INSTALL libavcodec/libavcodec.pc INSTALL libswresample/swresample.h INSTALL libswresample/version.h INSTALL libswresample/libswresample.pc INSTALL libswscale/swscale.h INSTALL libswscale/version.h INSTALL libswscale/libswscale.pc INSTALL libavutil/adler32.h INSTALL libavutil/aes.h INSTALL libavutil/attributes.h INSTALL libavutil/audio_fifo.h INSTALL libavutil/audioconvert.h INSTALL libavutil/avassert.h INSTALL libavutil/avstring.h INSTALL libavutil/avutil.h INSTALL libavutil/base64.h INSTALL libavutil/blowfish.h INSTALL libavutil/bprint.h INSTALL libavutil/bswap.h INSTALL libavutil/buffer.h INSTALL libavutil/channel_layout.h INSTALL libavutil/common.h INSTALL libavutil/cpu.h INSTALL libavutil/crc.h INSTALL libavutil/error.h INSTALL libavutil/eval.h INSTALL libavutil/fifo.h INSTALL libavutil/file.h INSTALL libavutil/frame.h INSTALL libavutil/hmac.h INSTALL libavutil/imgutils.h INSTALL libavutil/intfloat.h INSTALL libavutil/intfloat_readwrite.h INSTALL libavutil/intreadwrite.h INSTALL libavutil/lfg.h INSTALL libavutil/log.h INSTALL libavutil/mathematics.h INSTALL libavutil/md5.h INSTALL libavutil/mem.h INSTALL libavutil/murmur3.h INSTALL libavutil/dict.h INSTALL libavutil/old_pix_fmts.h INSTALL libavutil/opt.h INSTALL libavutil/parseutils.h INSTALL libavutil/pixdesc.h INSTALL libavutil/pixfmt.h INSTALL libavutil/random_seed.h INSTALL libavutil/rational.h INSTALL libavutil/ripemd.h INSTALL libavutil/samplefmt.h INSTALL libavutil/sha.h INSTALL libavutil/sha512.h INSTALL libavutil/time.h INSTALL libavutil/timecode.h INSTALL libavutil/timestamp.h INSTALL libavutil/version.h INSTALL libavutil/xtea.h INSTALL libavutil/lzo.h INSTALL libavutil/avconfig.h INSTALL libavutil/libavutil.pc link ffmpeg.
二、新建一个Android工程，在工程目录下新建一个jni文件夹，在文件夹下新建一个ffmpeg文件夹，用来放ffmpeg相关的头文件。在ffmpeg文件夹下新建Android.mk文件用来预先加载ffmpeg动态库。Android.mk文件内容如下：
LOCAL_PATH := $(call my-dir) include $(CLEAR_VARS) LOCAL_MODULE := ffmpeg LOCAL_SRC_FILES := /path/to/build/output/libffmpeg.so include $(PREBUILT_SHARED_LIBRARY)
三、在jni下新建Android.mk文件和Application.mk两个文件用来指定编译的顺序和编译的平台以及对应的cpu指令集。
Application.mk APP_ABI := armeabi APP_PLATFORM := android-9
Android.mk include $(call all-subdir-makefiles)
四、编写JNI文件，用来绑定java文件与.c文件的交互，文件内容如下：
/*
* ffmpeg_jni.c
*
* Created on: Sep 1, 2014
* Author: clarck
*/
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <jni.h>
#include "../include/ffmpeg_logger.h"
#include "../include/ffmpeg.h"
// 指定要注册的类，对应完整的java类名
#define JNIREG_CLASS "com/clarck/android/ffmpeg/MainActivity"
JNIEXPORT void JNICALL native_setDataSource(JNIEnv *env, jclass classzz, jstring path) {
char *filepath = ffmpeg_jstringTostr(env, path);
ffmpeg_setDataSource(filepath);
}
//Java和JNI函数的绑定
static JNINativeMethod method_table[] = {
{ "setDataSource", "(Ljava/lang/String;)V", native_setDataSource }
};
//注冊native方法到java中
static int registerNativeMethods(JNIEnv *env, const char *className,
JNINativeMethod *gMethods, int numMethods) {
jclass clazz;
clazz = (*env)->FindClass(env, className);
if (clazz == NULL) {
return JNI_FALSE;
}
if ((*env)->RegisterNatives(env, clazz, gMethods, numMethods) < 0) {
return JNI_FALSE;
}
return JNI_TRUE;
}
//調用註冊方法
int register_ndk_load(JNIEnv *env) {
return registerNativeMethods(env, JNIREG_CLASS, method_table,
(int) (sizeof(method_table) / sizeof(method_table[0])));
}
JNIEXPORT jint JNI_OnLoad(JavaVM *vm, void *reserved) {
JNIEnv *env = NULL;
jint result = -1;
if ((*vm)->GetEnv(vm, (void**)&env, JNI_VERSION_1_6) != JNI_OK) {
return result;
}
register_ndk_load(env);
//返回JNI的版本
return JNI_VERSION_1_6;
}
五、编写ffmpeg调用函数，内容如下：
/*
* ffmpeg.c
*
* Created on: Sep 1, 2014
* Author: clarck
*/
#include <jni.h>
#include <android/native_window_jni.h>
#include "../include/ffmpeg.h"
#include "../include/ffmpeg_logger.h"
#include "../ffmpeg/include/libavcodec/avcodec.h"
#include "../ffmpeg/include/libavformat/avformat.h"
#include "../ffmpeg/include/libavutil/pixfmt.h"
#include "../ffmpeg/include/libswscale/swscale.h"
char* ffmpeg_jstringTostr(JNIEnv* env, jstring jstr) {
char* pStr = NULL;
jclass jstrObj = (*env)->FindClass(env, "java/lang/String");
jstring encode = (*env)->NewStringUTF(env, "utf-8");
jmethodID methodId = (*env)->GetMethodID(env, jstrObj, "getBytes",
"(Ljava/lang/String;)[B");
jbyteArray byteArray = (jbyteArray) (*env)->CallObjectMethod(env, jstr,
methodId, encode);
jsize strLen = (*env)->GetArrayLength(env, byteArray);
jbyte *jBuf = (*env)->GetByteArrayElements(env, byteArray, JNI_FALSE);
if (jBuf > 0) {
pStr = (char*) malloc(strLen + 1);
if (!pStr) {
return NULL ;
}
memcpy(pStr, jBuf, strLen);
pStr[strLen] = 0;
}
(*env)->ReleaseByteArrayElements(env, byteArray, jBuf, 0);
return pStr;
}
void ffmpeg_setDataSource(char *file_path) {
LOGI("ffmpeg_setDataSource:%s", file_path);
AVFormatContext *pFormatCtx;
AVCodecContext *pCodecCtx;
AVCodec *pCodec;
AVFrame *pFrame, *pFrameYUV;
AVPacket *packet;
uint8_t *out_buffer;
static struct SwsContext *img_convert_ctx;
int videoStream, i, numBytes;
int ret, got_picture;
av_register_all();
pFormatCtx = avformat_alloc_context();
if (avformat_open_input(&pFormatCtx, file_path, NULL, NULL) != 0) {
LOGE("can‘t open the file. \n");
return;
}
if (avformat_find_stream_info(pFormatCtx, NULL) < 0) {
LOGE("Could‘t find stream infomation.\n");
return;
}
videoStream = 1;
for (i = 0; i < pFormatCtx->nb_streams; i++) {
if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
videoStream = i;
}
}
if (videoStream == -1) {
LOGE("Didn‘t find a video stream.\n");
return;
}
pCodecCtx = pFormatCtx->streams[videoStream]->codec;
pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
if (pCodec == NULL) {
LOGE("Codec not found.\n");
return;
}
if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0) {
LOGE("Could not open codec.\n");
return;
}
pFrame = av_frame_alloc();
pFrameYUV = av_frame_alloc();
numBytes = avpicture_get_size(AV_PIX_FMT_YUV420P, pCodecCtx->width,
pCodecCtx->height);
out_buffer = (uint8_t *) av_malloc(numBytes * sizeof(uint8_t));
avpicture_fill((AVPicture *) pFrameYUV, out_buffer, AV_PIX_FMT_YUV420P,
pCodecCtx->width, pCodecCtx->height);
int y_size = pCodecCtx->width * pCodecCtx->height;
packet = (AVPacket *) malloc(sizeof(AVPacket));
av_new_packet(packet, y_size);
av_dump_format(pFormatCtx, 0, file_path, 0);
while (av_read_frame(pFormatCtx, packet) >= 0) {
if (packet->stream_index == videoStream) {
ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture,
packet);
LOGI("avcodec_decode_video2 ret:%d", ret);
if (ret < 0) {
LOGE("decode error.\n");
return;
}
if (got_picture) {
//TODO 此处可以将解码出来的图片保存起来。
}
}
av_free_packet(packet);
}
av_free(out_buffer);
av_free(pFrameYUV);
avcodec_close(pCodecCtx);
avformat_close_input(&pFormatCtx);
}
六、编写Android.mk用来编译相关的.c文件，内容如下：
LOCAL_PATH := $(call my-dir) include $(CLEAR_VARS) FFMPEG_PATH := ../ffmpeg LOCAL_C_INCLUDES := $(LOCAL_PATH)/$(FFMPEG_PATH)/include LOCAL_MODULE := ffmpeg_player LOCAL_SRC_FILES += ffmpeg_jni.c LOCAL_SRC_FILES += ffmpeg.c LOCAL_SHARED_LIBRARIES := ffmpeg LOCAL_LDLIBS := -llog include $(BUILD_SHARED_LIBRARY)
七、编写java文件中相关执行调用方法
package com.clarck.android.ffmpeg;
import android.app.Activity;
import android.os.Bundle;
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
setDataSource("/sdcard/a.mp4");
}
public native void setDataSource(String path);
static {
System.loadLibrary("ffmpeg");
System.loadLibrary("ffmpeg_player");
}
}
八、执行结果如下图：
时间： 2024-10-11 05:12:09