微信网站的建立,做公司网站页面,泡棉制品东莞网站建设,万网域名查询网前言
我想大家都做过录音的功能吧#xff0c;首先想到的是不是MediaRecorder#xff1f;今天我们不用MediaRecorder#xff0c;而是使用LAME库自己编译音频编码模块#xff0c;很明显#xff0c;这个需要用到NDK。凡是涉及到音视频编解码这块的#xff0c;都需要用到And…前言
我想大家都做过录音的功能吧首先想到的是不是MediaRecorder今天我们不用MediaRecorder而是使用LAME库自己编译音频编码模块很明显这个需要用到NDK。凡是涉及到音视频编解码这块的都需要用到Android NDK(Native Development Kit)原生开发工具包。即使用C/C代码实现音频的采样和编码然后使用Java去调用原生模块实现录音功能。
音视频相关基础知识
我来简单过一下基础的音视频相关知识。 Audio Sample音频采样通常指录制音频采样文件PCM的过程PCM脉冲编码调制是一种音频流称为裸流。人耳听到的是模拟信号PCM是把声音从模拟信号转化为数字信号的技术。 Audio Track音轨封装格式的音频文件通常由多个音轨组成比如MP3文件就是一种封装格式的音频文件与之相对的就是音频原始采样数据PCM。比如一首歌歌声是一个音轨吉他声、鼓声等一些混合在其中的声音各自也是一个音轨。 Audio Channel声道比如左声道、右声道和环绕立体声。 Bitrate比特率俗称码率。它直接决定声音的清晰度即声音特征的详细程度SQ、HQ音质是通过它来判断的码率越高音频文件越大质量也越高。 Sample Rate采样率大多数沿用国际通用的标准采样率即44.100kHZ或者48.000kHZ肯定是不能录制超声波和次声波的因为人耳感知不到。 录音和播放声音的详细过程。 录音音频采样编码-音频封装 播放声音音频解封装-音频解码播放 录音首先采样并编码得到PCM文件然后封装PCM文件为MP3、WAV、FLAC等文件播放声音首先也要解封装成PCM文件然后对PCM文件解码播放。
编译共享库so
编译共享库so的过程有两种方式一种是使用ndk-buildAndroid.mkApplication.mk一种是CMakeCMakeLists.txt。今天我们采用最原始的方式mk文件。其实Android.mk和CMakeLists.txt很多东西是一一对应的。
Android.mkCMakeLists.txtLOCAL_MODULE、LOCAL_SRC_FILESadd_libraryLOCAL_CFLAGSadd_definitionsLOCAL_C_INCLUDESinclude_directoriesLOCAL_STATIC_LIBRARIES、LOCAL_SHARED_LIBRARIESadd_library set_target_propertiesLOCAL_LDLIBSfind_library
C文件 Android.mk
LOCAL_PATH : $(call my-dir)include $(CLEAR_VARS)LAME_LIBMP3_DIR : lame-3.100_libmp3lameLOCAL_MODULE : mp3lameLOCAL_SRC_FILES :\
$(LAME_LIBMP3_DIR)/bitstream.c \
$(LAME_LIBMP3_DIR)/fft.c \
$(LAME_LIBMP3_DIR)/id3tag.c \
$(LAME_LIBMP3_DIR)/mpglib_interface.c \
$(LAME_LIBMP3_DIR)/presets.c \
$(LAME_LIBMP3_DIR)/quantize.c \
$(LAME_LIBMP3_DIR)/reservoir.c \
$(LAME_LIBMP3_DIR)/tables.c \
$(LAME_LIBMP3_DIR)/util.c \
$(LAME_LIBMP3_DIR)/VbrTag.c \
$(LAME_LIBMP3_DIR)/encoder.c \
$(LAME_LIBMP3_DIR)/gain_analysis.c \
$(LAME_LIBMP3_DIR)/lame.c \
$(LAME_LIBMP3_DIR)/newmdct.c \
$(LAME_LIBMP3_DIR)/psymodel.c \
$(LAME_LIBMP3_DIR)/quantize_pvt.c \
$(LAME_LIBMP3_DIR)/set_get.c \
$(LAME_LIBMP3_DIR)/takehiro.c \
$(LAME_LIBMP3_DIR)/vbrquantize.c \
$(LAME_LIBMP3_DIR)/version.c \
MP3Encoder.cinclude $(BUILD_SHARED_LIBRARY)LOCAL_PATH :$(call my-dir) 当前文件在系统中的路径必须为Android.mk文件的第一行。include $(CLEAR_VARS) 清除上一次构建中的全局变量开始一次新的编译。LOCAL_MODULE 生成的模块的名称这里是动态库so文件的名称so文件的名称拼接为lib「模块名」.so 该模块的编译的目标名用于区分各个模块名字必须是唯一并不包含空格的如果编译目标是 so 库那么该 so 库的名称就是 lib 项目名 .so。LOCAL_SRC_FILES 要编译的.c或.cpp文件.h和.hpp文件可以不用出现在这里系统会自动包含。include $(BUILD_SHARED_LIBRARY) include开头的是构建系统的内置变量此行代码的意思是构建动态库也称共享库还有以下几种取值。 BUILD_STATIC_LIBRARY: 构建静态库。 PREBUILT_STATIC_LIBRARY: 将静态库包装成一个模块。 PREBUILT_SHARED_LIBRARY: 将静态库包装成一个模块。 BUILD_EXECUTABLE: 构建可执行文件。
Application.mk
APP_ABI : armeabi armeabi-v7a arm64-v8a x86 x86_64 mips mips64
APP_MODULES : mp3lame
APP_CFLAGS -DSTDC_HEADERS
APP_PLATFORM : android-21APP_ABI ABIApplication Binary Interface应用二级制接口这是一种计算机科学中的概念用于描述软件库或操作系统与应用程序之间的二进制通信方式。它跟CPU指令集对应。APP_MODULES 指定模块APP_FLAGS 指定编译过程的flag“DSTDC_HEADERS” 是一个编程中常见的宏定义通常用于检查标准库头文件是否已经包含。这个宏定义通常在C/C代码中使用用于确保标准库的头文件已经正确包含以便程序可以正常编译和运行。如果没有正确包含标准库头文件编译器可能会报错或者出现未定义的行为。APP_PLATFORM 指定创建的动态库的平台。
与JNI相关的文件
/* DO NOT EDIT THIS FILE - it is machine generated */
#include jni.h#ifndef _Included_Mp3Encoder
#define _Included_Mp3Encoder
#ifdef __cplusplus
extern C {
#endifJNIEXPORT void JNICALL Java_com_dorachat_dorachat_recorder_mp3_Mp3Encoder_init(JNIEnv *, jclass, jint, jint, jint, jint, jint);JNIEXPORT jint JNICALL Java_com_dorachat_dorachat_recorder_mp3_Mp3Encoder_encode(JNIEnv *, jclass, jshortArray, jshortArray, jint, jbyteArray);JNIEXPORT jint JNICALL Java_com_dorachat_dorachat_recorder_mp3_Mp3Encoder_flush(JNIEnv *, jclass, jbyteArray);JNIEXPORT void JNICALL Java_com_dorachat_dorachat_recorder_mp3_Mp3Encoder_close(JNIEnv *, jclass);#ifdef __cplusplus
}
#endif
#endiflame的jni层主要定义4个方法init、encode、flush和close。
#include lame-3.100_libmp3lame/lame.h
#include Mp3Encoder.hstatic lame_global_flags *glf NULL;JNIEXPORT void JNICALL Java_com_dorachat_dorachat_recorder_mp3_Mp3Encoder_init(JNIEnv *env, jclass cls, jint inSamplerate, jint outChannel,jint outSamplerate, jint outBitrate, jint quality) {if (glf ! NULL) {lame_close(glf);glf NULL;}glf lame_init();lame_set_in_samplerate(glf, inSamplerate);lame_set_num_channels(glf, outChannel);lame_set_out_samplerate(glf, outSamplerate);lame_set_brate(glf, outBitrate);lame_set_quality(glf, quality);lame_init_params(glf);
}JNIEXPORT jint JNICALL
Java_com_dorachat_dorachat_recorder_mp3_Mp3Encoder_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(glf, 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_dorachat_dorachat_recorder_mp3_Mp3Encoder_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(glf, j_mp3buf, mp3buf_size);(*env)-ReleaseByteArrayElements(env, mp3buf, j_mp3buf, 0);return result;
}JNIEXPORT void JNICALL Java_com_dorachat_dorachat_recorder_mp3_Mp3Encoder_close(JNIEnv *env, jclass cls) {lame_close(glf);glf NULL;
}这个需要你会一点C语言的基础然后就可以轻松调用lame库的函数了。
package com.dorachat.dorachat.recorder.mp3;public class Mp3Encoder {static {System.loadLibrary(mp3lame);}public native static void close();public native static int encode(short[] buffer_l, short[] buffer_r, int samples, byte[] mp3buf);public native static int flush(byte[] mp3buf);public native static void init(int inSampleRate, int outChannel, int outSampleRate, int outBitrate, int quality);public static void init(int inSampleRate, int outChannel, int outSampleRate, int outBitrate) {init(inSampleRate, outChannel, outSampleRate, outBitrate, 7);}
}我们再看一下java层。
Java层大致实现
我们录音肯定是要在后台Service中进行的可以使用onStartCommand进行调用这里只是一个简单的功能就不使用aidl跨进程了。开始录音时我们需要开一个线程去采样音频数据。
public void start(String filePath, RecordConfig config) {this.currentConfig config;if (state ! RecordState.IDLE state ! RecordState.STOP) {Logger.e(TAG, 状态异常当前状态 %s, state.name());return;}resultFile new File(filePath);String tempFilePath getTempFilePath();LogUtils.dformat(TAG, ----------------开始录制 %s------------------------, currentConfig.getFormat().name());LogUtils.dformat(TAG, 参数 %s, currentConfig.toString());LogUtils.iformat(TAG, pcm缓存 tmpFile: %s, tempFilePath);LogUtils.iformat(TAG, 录音文件 resultFile: %s, filePath);tmpFile new File(tempFilePath);audioRecordThread new AudioRecordThread();audioRecordThread.start();
}private class AudioRecordThread extends Thread {private AudioRecord audioRecord;private int bufferSize;AudioRecordThread() {bufferSize AudioRecord.getMinBufferSize(currentConfig.getSampleRate(),currentConfig.getChannelConfig(), currentConfig.getEncodingConfig()) * RECORD_AUDIO_BUFFER_TIMES;Logger.d(TAG, record buffer size %s, bufferSize);audioRecord new AudioRecord(MediaRecorder.AudioSource.MIC, currentConfig.getSampleRate(),currentConfig.getChannelConfig(), currentConfig.getEncodingConfig(), bufferSize);if (currentConfig.getFormat() RecordConfig.RecordFormat.MP3) {if (mp3EncodeThread null) {initMp3EncoderThread(bufferSize);} else {LogUtils.e(mp3EncodeThread ! null, 请检查代码);}}}Overridepublic void run() {super.run();switch (currentConfig.getFormat()) {case MP3:startMp3Recorder();break;default:startPcmRecorder();break;}}private void startPcmRecorder() {state RecordState.RECORDING;notifyState();LogUtils.d(开始录制PCM);FileOutputStream fos null;try {fos new FileOutputStream(tmpFile);audioRecord.startRecording();byte[] byteBuffer new byte[bufferSize];while (state RecordState.RECORDING) {int end audioRecord.read(byteBuffer, 0, byteBuffer.length);notifyData(byteBuffer);fos.write(byteBuffer, 0, end);fos.flush();}audioRecord.stop();files.add(tmpFile);if (state RecordState.STOP) {makeFile();} else {LogUtils.i(暂停);}} catch (Exception e) {LogUtils.e(e.getMessage());notifyError(录音失败);} finally {try {if (fos ! null) {fos.close();}} catch (IOException e) {e.printStackTrace();}}if (state ! RecordState.PAUSE) {state RecordState.IDLE;notifyState();LogUtils.d(录音结束);}}private void startMp3Recorder() {state RecordState.RECORDING;notifyState();try {audioRecord.startRecording();short[] byteBuffer new short[bufferSize];while (state RecordState.RECORDING) {int end audioRecord.read(byteBuffer, 0, byteBuffer.length);if (mp3EncodeThread ! null) {mp3EncodeThread.addChangeBuffer(new Mp3EncodeThread.ChangeBuffer(byteBuffer, end));}notifyData(ByteUtils.toBytes(byteBuffer));}audioRecord.stop();} catch (Exception e) {LogUtils.e(e.getMessage());notifyError(录音失败);}if (state ! RecordState.PAUSE) {state RecordState.IDLE;notifyState();stopMp3Encoded();} else {LogUtils.d(暂停);}}
}private void stopMp3Encoded() {if (mp3EncodeThread ! null) {mp3EncodeThread.stopSafe(new Mp3EncodeThread.EncordFinishListener() {Overridepublic void onFinish() {notifyFinish();mp3EncodeThread null;}});} else {LogUtils.e(mp3EncodeThread is null, 代码业务流程有误请检查);}
}private void makeFile() {switch (currentConfig.getFormat()) {case MP3:return;case WAV:mergePcmFile();makeWav();break;case PCM:mergePcmFile();break;default:break;}notifyFinish();LogUtils.i(录音完成 path: %s 大小%s, resultFile.getAbsoluteFile(), resultFile.length());
}/*** 添加Wav头文件。*/
private void makeWav() {if (!FileUtils.isFile(resultFile) || resultFile.length() 0) {return;}byte[] header WavUtils.generateWavFileHeader((int) resultFile.length(), currentConfig.getSampleRate(), currentConfig.getChannelCount(), currentConfig.getEncoding());WavUtils.writeHeader(resultFile, header);
}/*** 合并文件。*/
private void mergePcmFile() {boolean mergeSuccess mergePcmFiles(resultFile, files);if (!mergeSuccess) {notifyError(合并失败);}
}/*** 合并PCM文件。** param recordFile 输出文件* param files 多个文件源* return 是否成功*/
private boolean mergePcmFiles(File recordFile, ListFile files) {if (recordFile null || files null || files.size() 0) {return false;}FileOutputStream fos null;BufferedOutputStream outputStream null;byte[] buffer new byte[1024];try {fos new FileOutputStream(recordFile);outputStream new BufferedOutputStream(fos);for (int i 0; i files.size(); i) {BufferedInputStream inputStream new BufferedInputStream(new FileInputStream(files.get(i)));int readCount;while ((readCount inputStream.read(buffer)) 0) {outputStream.write(buffer, 0, readCount);}inputStream.close();}} catch (Exception e) {LogUtils.e(e.getMessage());return false;} finally {try {if (outputStream ! null) {outputStream.close();}if (fos ! null) {fos.close();}} catch (IOException e) {e.printStackTrace();}}for (int i 0; i files.size(); i) {files.get(i).delete();}files.clear();return true;
}/*** 根据当前的时间生成相应的文件名。*/
private String getTempFilePath() {String fileDir String.format(Locale.getDefault(), %s/Record/, Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_MUSIC).getAbsolutePath());if (!FileUtils.createOrExistsDir(fileDir)) {LogUtils.e(文件夹创建失败 fileDir);}String fileName String.format(Locale.getDefault(), record_tmp_%s, FileUtils.getNowString(new SimpleDateFormat(yyyyMMdd_HH_mm_ss, Locale.SIMPLIFIED_CHINESE)));return String.format(Locale.getDefault(), %s%s.pcm, fileDir, fileName);
}/*** 表示当前录制状态。*/
public enum RecordState {/*** 空闲状态。*/IDLE,/*** 录音中。*/RECORDING,/*** 暂停中。*/PAUSE,/*** 正在停止。*/STOP,/*** 录音流程结束转换结束。*/FINISH
}在Mp3EncodeThread中init初始化录制参数然后调用encode进行编码录制录制完成调用flush把缓冲区冲一下水清洗一下。最后调用一下close完美。 最后附上录制流程细节的代码。
package com.dorachat.dorachat.recorder.mp3;import com.dorachat.dorachat.recorder.RecordConfig;
import com.dorachat.dorachat.recorder.RecordService;import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Collections;
import java.util.LinkedList;
import java.util.List;public class Mp3EncodeThread extends Thread {private static final String TAG Mp3EncodeThread.class.getSimpleName();private ListChangeBuffer cacheBufferList Collections.synchronizedList(new LinkedListChangeBuffer());private File file;private FileOutputStream os;private byte[] mp3Buffer;private EncodeFinishListener encodeFinishListener;/*** 是否已停止录音。*/private volatile boolean isOver false;/*** 是否继续轮询数据队列。*/private volatile boolean start true;public Mp3EncodeThread(File file, int bufferSize) {this.file file;mp3Buffer new byte[(int) (7200 (bufferSize * 2 * 1.25))];RecordConfig currentConfig RecordService.getCurrentConfig();int sampleRate currentConfig.getSampleRate();Mp3Encoder.init(sampleRate, currentConfig.getChannelCount(), sampleRate, currentConfig.getRealEncoding());}Overridepublic void run() {try {this.os new FileOutputStream(file);} catch (FileNotFoundException e) {return;}while (start) {ChangeBuffer next next();lameData(next);}}public void addChangeBuffer(ChangeBuffer changeBuffer) {if (changeBuffer ! null) {cacheBufferList.add(changeBuffer);synchronized (this) {notify();}}}public void stopSafe(EncodeFinishListener encodeFinishListener) {this.encodeFinishListener encodeFinishListener;isOver true;synchronized (this) {notify();}}private ChangeBuffer next() {for (;;) {if (cacheBufferList null || cacheBufferList.size() 0) {try {if (isOver) {finish();}synchronized (this) {wait();}} catch (Exception e) {}} else {return cacheBufferList.remove(0);}}}private void lameData(ChangeBuffer changeBuffer) {if (changeBuffer null) {return;}short[] buffer changeBuffer.getData();int readSize changeBuffer.getReadSize();if (readSize 0) {int encodedSize Mp3Encoder.encode(buffer, buffer, readSize, mp3Buffer);try {os.write(mp3Buffer, 0, encodedSize);} catch (IOException e) {}}}private void finish() {start false;final int flushResult Mp3Encoder.flush(mp3Buffer);if (flushResult 0) {try {os.write(mp3Buffer, 0, flushResult);os.close();} catch (final IOException e) {}}if (encodeFinishListener ! null) {encodeFinishListener.onFinish();}}public static class ChangeBuffer {private short[] rawData;private int readSize;public ChangeBuffer(short[] rawData, int readSize) {this.rawData rawData.clone();this.readSize readSize;}short[] getData() {return rawData;}int getReadSize() {return readSize;}}public interface EncodeFinishListener {/*** 格式转换完毕。*/void onFinish();}
}总结
这只是Android音视频开发的冰山一角主要是为了演示大概的开发流程如果需要深入研究Android NDK一定需要先把C/C语言学好这样才能走得更远。
