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platformsandroid-8arch-armusrlib文件夹下就可以了。

  再看下我们的代码吧：

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 +"
"+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

/*
 * 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
");
    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
");
    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
");
        return 0; // Didn't find a audio stream

    }
    LOGE("audio stream num: %d
", 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
",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
");
        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.
");
        return -1; // Could not open codec

    }

    if (avcodec_open(pInCodecCtx, pInCodec) < 0) {
        printf("error avcodec_open failed.
");
        return -1; // Could not open codec

    }

    static AVPacket packet;

    LOGI(" bit_rate = %d 
", pInCodecCtx->bit_rate);
    LOGI(" sample_rate = %d 
", pInCodecCtx->sample_rate);
    LOGI(" channels = %d 
", pInCodecCtx->channels);
    LOGI(" code_name = %s 
", pInCodecCtx->codec->name);
    //LOGI("extra data size: %d :data%x %x %x %x
",pInCodecCtx->extradata_size,pInCodecCtx->extradata[0]
    // ,pInCodecCtx->extradata[1],pInCodecCtx->extradata[2],pInCodecCtx->extradata[3]);
    LOGI(" block_align = %d
", 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!
");
                    break;
                }
                if (outsize > 0) {
                    fwrite(outbuf, 1, outsize, out_fp);
                    printf("write %d bytes
", outsize);
                }
                declen += len;
                if (declen == size) {
                    av_free_packet(&aacpkt);
                    printf("packet decoded succeed!
");
                    break;
                } else if (declen < size) {
                    aacpkt.size -= len;
                    aacpkt.data += len;
                } else {
                    printf("decode error!
");
                    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：

 

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.