FFmpeg在Android使用3

android 移植ffmpeg后so库的使用

只需要将我们编译好的ffmpeg的so包（在/obj/local/armeabi/libffmpeg.so）copy到所在ndk下的\platforms\android-8\arch-arm\usr\lib文件夹下就可以了。
再看下我们的代码吧：

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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);

String str = String.valueOf(stringFromJNI());

str = str +"\n"+getVoice();

tv.setText(str);

setContentView(tv);

}

public native int getVoice();

public native String stringFromJNI();

public native String unimplementedStringFromJNI();

static {

System.loadLibrary("ffmpeg");

System.loadLibrary("hello-jni");

}

}

这个是Android上层的使用。下面附上c层的代码

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/*

* 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 <jni.h>

#include <android/log.h>

#include <ffmpeg/libavcodec/avcodec.h>

#include <ffmpeg/libavformat/avformat.h>

#include <ffmpeg/libswscale/swscale.h>

#include <string.h>

#define LOG_TAG "***************************lixingyun*****************" // 这个是自定义的LOG的标识

#undef LOG // 取消默认的LOG

#define LOGD(...) __android_log_print(ANDROID_LOG_DEBUG,LOG_TAG,__VA_ARGS__) // 定义LOG类型

#define LOGI(...) __android_log_print(ANDROID_LOG_INFO,LOG_TAG,__VA_ARGS__) // 定义LOG类型

#define LOGW(...) __android_log_print(ANDROID_LOG_WARN,LOG_TAG,__VA_ARGS__) // 定义LOG类型

#define LOGE(...) __android_log_print(ANDROID_LOG_ERROR,LOG_TAG,__VA_ARGS__) // 定义LOG类型

#define LOGF(...) __android_log_print(ANDROID_LOG_FATAL,LOG_TAG,__VA_ARGS__) // 定义LOG类型

/* 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

*/

JNIEXPORT jstring Java_com_example_hellojni_HelloJni_stringFromJNI(JNIEnv* env,

jobject thiz) {

char str[25];

sprintf(str, "%d", avcodec_version());

return (*env)->NewStringUTF(env, str);

// return (*env)->NewStringUTF(env, "Hello from JNI !");0

}

JNIEXPORT jint Java_com_example_hellojni_HelloJni_getVoice(JNIEnv* env,

jobject thiz) {

int flag = 0;

AVPacket aacpkt;

aacpkt.data = NULL;

aacpkt.size = 0;

const char *filename = "file:/sdcard/test.mp3";

av_init_packet(&aacpkt);

av_register_all(); //注册所有可解码类型

AVFormatContext *pInFmtCtx = NULL; //文件格式

AVCodecContext *pInCodecCtx = NULL; //编码格式

pInFmtCtx = avformat_alloc_context();

if (av_open_input_file(&pInFmtCtx, filename, NULL, 0, NULL) != 0) //获取文件格式

LOGE("av_open_input_file error\n");

if (av_find_stream_info(pInFmtCtx) < 0) //获取文件内音视频流的信息

LOGE("av_find_stream_info error\n");

unsigned int j;

// Find the first audio stream

int audioStream = -1;

// Dump information about file onto standard error

dump_format(pInFmtCtx, 0, filename, 0);

//从FormatdContext的中找到对应流对应的编码类型，若是CODEC_TYPE_AUDIO则表示是音频

for (j = 0; j < pInFmtCtx->nb_streams; j++) //找到音频对应的stream

if (pInFmtCtx->streams[j]->codec->codec_type == CODEC_TYPE_AUDIO) {

audioStream = j;

break;

}

if (audioStream == -1) {

printf("input file has no audio stream\n");

return 0; // Didn't find a audio stream

}

LOGE("audio stream num: %d\n", audioStream);

pInCodecCtx = pInFmtCtx->streams[audioStream]->codec; //音频的编码上下文

AVCodec *pInCodec = NULL;

/* FILE *file3 = fopen("codec_private_data_size.txt","w");

for(int i = 0; i <200000; i++)

{

pInCodec = avcodec_find_decoder((CodecID)i);

if (pInCodec!=NULL)

{

fprintf(file3,"%s %d\n",pInCodec->name,pInCodec->priv_data_size );

}

}

fclose(file3);

system("pause");

*/

pInCodec = avcodec_find_decoder(pInCodecCtx->codec_id); //根据编码ID找到用于解码的结构体

if (pInCodec == NULL) {

printf("error no Codec found\n");

return -1; // Codec not found

}

//使用test的代替pInCodecCtx也可以完成解码，可以看出只要获取以下几个重要信息就可以实现解码和重采样

AVCodecContext *test = avcodec_alloc_context();

test->bit_rate = pInCodecCtx->bit_rate; //重采样用

test->sample_rate = pInCodecCtx->sample_rate; //重采样用

test->channels = pInCodecCtx->channels; //重采样用

test->extradata = pInCodecCtx->extradata; //若有则必有

test->extradata_size = pInCodecCtx->extradata_size; //若有则必要

test->codec_type = CODEC_TYPE_AUDIO; //不必要

test->block_align = pInCodecCtx->block_align; //必要

if (avcodec_open(test, pInCodec) < 0) //将两者结合以便在下面的解码函数中调用pInCodec中的对应解码函数

{

printf("error avcodec_open failed.\n");

return -1; // Could not open codec

}

if (avcodec_open(pInCodecCtx, pInCodec) < 0) {

printf("error avcodec_open failed.\n");

return -1; // Could not open codec

}

static AVPacket packet;

LOGI(" bit_rate = %d \r\n", pInCodecCtx->bit_rate);

LOGI(" sample_rate = %d \r\n", pInCodecCtx->sample_rate);

LOGI(" channels = %d \r\n", pInCodecCtx->channels);

LOGI(" code_name = %s \r\n", pInCodecCtx->codec->name);

//LOGI("extra data size: %d :data%x %x %x %x\n",pInCodecCtx->extradata_size,pInCodecCtx->extradata[0]

// ,pInCodecCtx->extradata[1],pInCodecCtx->extradata[2],pInCodecCtx->extradata[3]);

LOGI(" block_align = %d\n", pInCodecCtx->block_align);

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

unsigned char *outbuf = NULL;

outbuf = (unsigned char *) malloc(AVCODEC_MAX_AUDIO_FRAME_SIZE * 2);

int outsize;

outsize = AVCODEC_MAX_AUDIO_FRAME_SIZE * 2;

int len = 0;

int size = 0;

FILE *out_fp;

out_fp = fopen("out.dat", "wb+");

while (av_read_frame(pInFmtCtx, &aacpkt) >= 0) {

LOGI("***************************");

if (aacpkt.stream_index == audioStream) {

int declen = 0;

size = aacpkt.size;

while (aacpkt.size > 0) {

outsize = AVCODEC_MAX_AUDIO_FRAME_SIZE * 2;

memset(outbuf, 0, outsize);

len = avcodec_decode_audio3(pInCodecCtx, (int16_t *) outbuf,

&outsize, &aacpkt);

if (len < 0) {

printf("avcodec_decode_audio3 failed!\n");

break;

}

if (outsize > 0) {

fwrite(outbuf, 1, outsize, out_fp);

printf("write %d bytes\n", outsize);

}

declen += len;

if (declen == size) {

av_free_packet(&aacpkt);

printf("packet decoded succeed!\n");

break;

} else if (declen < size) {

aacpkt.size -= len;

aacpkt.data += len;

} else {

printf("decode error!\n");

break;

}

}

}

}

fclose(out_fp);

// Close the codec

avcodec_close(pInCodecCtx);

// Close the video file

av_close_input_file(pInFmtCtx);

return flag;

}


其中的LOGE那几个就是Android下的哦。
再附上Android.mk的东西吧：

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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 -llog

LOCAL_MODULE := hello-jni

LOCAL_SRC_FILES := hello-jni.c

include $(BUILD_SHARED_LIBRARY)

哈哈，这样就Ok了。
源码也附上吧.