MP3 录音开发

Dear 丶 2024-02-17 21:03 8阅读 0赞

### NDK环境配置 ###

这里主要是介绍Eclipse的NDK开发环境配置，至于Android Studio的配置比较简单，自行Google吧。。。

###### 下载安装CDT ######

多的不解释，Eclipse插件安装

[https://dl.google.com/android/eclipse/][https_dl.google.com_android_eclipse]

![j7BlaWh.png][]

安装完成重启即可

###### 下载安装NDK ######

同样，上官网下载相应的NDK

[NDK下载地址][NDK]

下载完成解压放在适当的目录下

若出现下面的情况

![GvKciUB.png][]

说明NDK版本过高，请下载低一些的版本，正确后如下

![bcmOhpM.png][]

到此NDK开发环境就配置完成了，当然这是基于安装的jdk版本是1.7以上的情况，若是1.6的话，还要安装cygwin,当然也还有其他一些配置

实在是必须在1.6环境下进行NDK开发，可以看这篇文章  
[Android NDK开发(一)——环境搭建][Android NDK]

### LAME编译 ###

[Lame在线下载地址][Lame]

1.  新建的项目根目录下建立jni目录
2.  解压下载的lame-3.99.5.tar.gz文件，拷贝libmp3lame文件夹下的文件到jni目录下
3.  拷贝 lame.h到jni目录 （include目录下）
4.  删除非.c /.h文件
5.  编辑 jni/util.h,在574行把 extern ieee754\_float32\_t fast\_log2(ieee754\_float32\_t x);替换为 extern float fast\_log2(float x);。
6.  创建Android.mk  
    LOCAL\_PATH := $(call my-dir)
    
    include $(CLEAR\_VARS)
    
    LOCAL\_MODULE := mp3lame
    
    LOCAL\_SRC\_FILES := bitstream.c fft.c id3tag.c mpglib\_interface.c presets.c quantize.c reservoir.c tables.c util.c VbrTag.c encoder.c gain\_analysis.c lame.c newmdct.c psymodel.c quantize\_pvt.c set\_get.c takehiro.c vbrquantize.c version.c lame\_util.c
    
    LOCAL\_LDLIBS += -llog
    
    include $(BUILD\_SHARED\_LIBRARY)
7.  创建Application.mk
    
    APP\_PLATFORM := android-9
    
    APP\_ABI := all //输出的.so版本,all表示全部
    
    APP\_CFLAGS += -DSTDC\_HEADERS

### 在Java层编写调用C端的代码 ###

public class LameUtil {
        
            static{
                System.loadLibrary("mp3lame");
            }
    
        /**
         * Initialize LAME.
         */
        public native static void init(int inSamplerate, int inChannel,
                    int outSamplerate, int outBitrate, int quality);
    
    
        /**
         * Encode buffer to mp3.
         */
        public native static int encode(short[] bufferLeft, short[] bufferRight,
                                        int samples, byte[] mp3buf);
    
        /**
         * Flush LAME buffer.
         */
        public native static int flush(byte[] mp3buf);
    
        /**
         * Close LAME.
         */
        public native static void close();
        }

### 编译头文件 ###

jdk\_1.7 及以上版本直接到项目src目录，以下到class目录

![hGcb7tn.png][]

如此成功后会在jni目录下生成如下文件

![8yUBg0H.png][]

看下生成的文件内容

/* DO NOT EDIT THIS FILE - it is machine generated */
        #include <jni.h>
        /* Header for class com_autolink_mp3library_util_LameUtil */
    
        #ifndef _Included_com_autolink_mp3library_util_LameUtil
        #define _Included_com_autolink_mp3library_util_LameUtil
        #ifdef __cplusplus
        extern "C" {
        #endif
        /*
         * Class:     com_autolink_mp3library_util_LameUtil
         * Method:    init
         * Signature: (IIIII)V
         */
        JNIEXPORT void JNICALL Java_com_autolink_mp3library_util_LameUtil_init
          (JNIEnv *, jclass, jint, jint, jint, jint, jint);
    
        /*
         * Class:     com_autolink_mp3library_util_LameUtil
         * Method:    encode
         * Signature: ([S[SI[B)I
         */
        JNIEXPORT jint JNICALL Java_com_autolink_mp3library_util_LameUtil_encode
          (JNIEnv *, jclass, jshortArray, jshortArray, jint, jbyteArray);
    
        /*
         * Class:     com_autolink_mp3library_util_LameUtil
         * Method:    flush
         * Signature: ([B)I
         */
        JNIEXPORT jint JNICALL Java_com_autolink_mp3library_util_LameUtil_flush
          (JNIEnv *, jclass, jbyteArray);
    
        /*
         * Class:     com_autolink_mp3library_util_LameUtil
         * Method:    close
         * Signature: ()V
         */
        JNIEXPORT void JNICALL Java_com_autolink_mp3library_util_LameUtil_close
          (JNIEnv *, jclass);
    
        #ifdef __cplusplus
        }
        #endif
        #endif

### 编写本地C语言代码，实现音频文件的转码 ###

#include "lame.h"
        #include "com_autolink_mp3library_util_LameUtil.h"
        #include <stdio.h>
        #include <jni.h>
    
        static lame_global_flags *lame = NULL;
    
        JNIEXPORT void JNICALL Java_com_autolink_mp3library_util_LameUtil_init(
                JNIEnv *env, jclass cls, jint inSamplerate, jint inChannel, jint outSamplerate, jint outBitrate, jint quality) {
            if (lame != NULL) {
                lame_close(lame);
                lame = NULL;
            }
            lame = lame_init();
            lame_set_in_samplerate(lame, inSamplerate);
            lame_set_num_channels(lame, inChannel);//杈撳叆娴佺殑澹伴亾
            lame_set_out_samplerate(lame, outSamplerate);
            lame_set_brate(lame, outBitrate);
            lame_set_quality(lame, quality);
            lame_init_params(lame);
        }
    
        JNIEXPORT jint JNICALL Java_com_autolink_mp3library_util_LameUtil_encode(
                JNIEnv *env, jclass cls, jshortArray buffer_l, jshortArray buffer_r,
                jint samples, jbyteArray mp3buf) {
            jshort* j_buffer_l = (*env)->GetShortArrayElements(env, buffer_l, NULL);
    
            jshort* j_buffer_r = (*env)->GetShortArrayElements(env, buffer_r, NULL);
    
            const jsize mp3buf_size = (*env)->GetArrayLength(env, mp3buf);
            jbyte* j_mp3buf = (*env)->GetByteArrayElements(env, mp3buf, NULL);
    
            int result = lame_encode_buffer(lame, j_buffer_l, j_buffer_r,
                    samples, j_mp3buf, mp3buf_size);
    
            (*env)->ReleaseShortArrayElements(env, buffer_l, j_buffer_l, 0);
            (*env)->ReleaseShortArrayElements(env, buffer_r, j_buffer_r, 0);
            (*env)->ReleaseByteArrayElements(env, mp3buf, j_mp3buf, 0);
    
            return result;
        }
    
        JNIEXPORT jint JNICALL Java_com_autolink_mp3library_util_LameUtil_flush(
                JNIEnv *env, jclass cls, jbyteArray mp3buf) {
            const jsize mp3buf_size = (*env)->GetArrayLength(env, mp3buf);
            jbyte* j_mp3buf = (*env)->GetByteArrayElements(env, mp3buf, NULL);
    
            int result = lame_encode_flush(lame, j_mp3buf, mp3buf_size);
    
            (*env)->ReleaseByteArrayElements(env, mp3buf, j_mp3buf, 0);
    
            return result;
        }
    
        JNIEXPORT void JNICALL Java_com_autolink_mp3library_util_LameUtil_close
        (JNIEnv *env, jclass cls) {
            lame_close(lame);
            lame = NULL;
        }

### 新建C++编译器 ###

右键项目Properties->Builders在右边的选项卡中点击“New”新建编译器（选择Program）：

![jLI63Oy.png][]

配置Main、Refresh和Build Options选项卡，如图

![gib1D6x.png][]

![8cPlbOK.png][]

![EpPhhtV.png][]

如此之后，clean一下工程即会自动编译获得.so文件

最后给项目加上下面两个权限

<uses-permission android:name="android.permission.RECORD_AUDIO" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

如何使用呢

package com.autolink.mp3library;
    
        import java.io.File;
        import java.io.IOException;
    
        import com.autolink.mp3library.util.MP3Recorder;
    
        import android.app.Activity;
        import android.os.Bundle;
        import android.os.Environment;
        import android.view.View;
        import android.view.View.OnClickListener;
    
    
        public class MainActivity extends Activity {
        
    
            private MP3Recorder mRecorder = new MP3Recorder(new File(Environment.getExternalStorageDirectory(), "test.mp3"));
    
            @Override
            protected void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
                setContentView(R.layout.activity_main);
    
                findViewById(R.id.StartButton).setOnClickListener(new OnClickListener() {
    
                    @Override
                    public void onClick(View v) {
                        try {
                            mRecorder.start();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                });
    
                findViewById(R.id.StopButton).setOnClickListener(new OnClickListener() {
    
                    @Override
                    public void onClick(View v) {
                        mRecorder.stop();
                    }
                });
            }
    
            @Override
            protected void onDestroy() {
                super.onDestroy();
                mRecorder.stop();
            }
    
        }

参考链接：

[http://blog.csdn.net/allen315410/article/details/42456661][http_blog.csdn.net_allen315410_article_details_42456661]

[http://blog.csdn.net/whurs/article/details/45487521][http_blog.csdn.net_whurs_article_details_45487521]

Android studio 可看下面这个

[http://www.cnblogs.com/ct2011/p/4080193.html][http_www.cnblogs.com_ct2011_p_4080193.html]

[https_dl.google.com_android_eclipse]: https://dl.google.com/android/eclipse/
[j7BlaWh.png]: http://i.imgur.com/j7BlaWh.png
[NDK]: https://developer.android.com/ndk/index.html
[GvKciUB.png]: http://i.imgur.com/GvKciUB.png
[bcmOhpM.png]: http://i.imgur.com/bcmOhpM.png
[Android NDK]: http://blog.csdn.net/allen315410/article/details/41800955
[Lame]: http://lame.sourceforge.net/
[hGcb7tn.png]: http://i.imgur.com/hGcb7tn.png
[8yUBg0H.png]: http://i.imgur.com/8yUBg0H.png
[jLI63Oy.png]: http://i.imgur.com/jLI63Oy.png
[gib1D6x.png]: http://i.imgur.com/gib1D6x.png
[8cPlbOK.png]: http://i.imgur.com/8cPlbOK.png
[EpPhhtV.png]: http://i.imgur.com/EpPhhtV.png
[http_blog.csdn.net_allen315410_article_details_42456661]: http://blog.csdn.net/allen315410/article/details/42456661
[http_blog.csdn.net_whurs_article_details_45487521]: http://blog.csdn.net/whurs/article/details/45487521
[http_www.cnblogs.com_ct2011_p_4080193.html]: http://www.cnblogs.com/ct2011/p/4080193.html