Opus从入门到精通(三)手撸一个Opus编码程序
前面Opus从入门到精通(二):编解码器使用介绍了opus编解码器的API,这边文章介绍编码API的具体使用示例.分Android,ios,Linux三个系统进行实现.
编码是我们对脉冲编码调制(Pulse Code Modulation,PCM)的数据进行压缩操作,我们通常通过操作系统麦克风API获取PCM数据,或者从存储的现成的文件的PCM数据:
麦克风回调二进制:
- Android的AudioRecorder - IOS的Audio Unit麦克风存储到文件:
- Android的MediaRecorder - IOS的AVFoundation AVAudioRecorder
PCM数据大小怎么计算呢?根据采样率采样格式,声道数计算.根据前面文章音视频之音频知识入门介绍:
PCM文件大小 = 采样率 采样格式 声道数 * 录制时长
采样率即一秒多少采样,采样格式指一个采用占多少字节,通常一个采用使用一个字节或者两个字节,所以采样率*采样格式计算出一秒钟一个声道PCM多少字节,乘以声道数,算出一秒钟PCM大小,再乘以时长就可以计算出PCM文件大小.
下面分别使用Android平台的麦克风二进制回调方式和IOS平台的麦克风文件回调方式采集,并使用OPUS编码器进行编码.
Android平台编码程序实现
配置工程
AndroidStudio新建工程,在见一个Andorid Library模块library,在library下面新建类OpusUtil,并写好native方法:
public class OpusUtil {
static {
System.loadLibrary("opusutil-lib");
}
//创建编码器
public static native long _createOpusEncoder(int sampleRateInHz, int channel, int bitrate,
int complexity);
//编码一帧PCM数据
public static native int _encodeOpus(long enc, short[] buffer, int offset, byte[] encoded);
//释放编码器
public static native void _destroyOpusEncoder(long enc);
}在src/main下面新建cpp目录,把从官网下载的opus编码器拷贝到cpp下,新建media_jni.c用于实现JNI方法
在library根目录下创建我们的CMakeLists.txt,并在build.gradle下面配置cmake文件:
externalNativeBuild {
cmake {
path file('CMakeLists.txt')
}CMakeLists.txt将opus编码器文件配置好:
# For more information about using CMake with Android Studio, read the
# documentation: https://d.android.com/studio/projects/add-native-code.html
# Sets the minimum version of CMake required to build the native library.
cmake_minimum_required(VERSION 3.4.1)
set(CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE} -s")
set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -s")
set(libs_include_opus_DIR src/main/cpp/libopus)
include_directories(
${libs_include_opus_DIR}/include
${libs_include_opus_DIR}/celt
${libs_include_opus_DIR}/silk
${libs_include_opus_DIR}/silk/float
${libs_include_opus_DIR}/src)
add_library(
opusutil-lib
SHARED
src/main/cpp/util.c
src/main/cpp/media_jni.c
src/main/cpp/jni_utils.c
src/main/cpp/libopus/src/opus_multistream_decoder.c
src/main/cpp/libopus/src/opus_multistream_encoder.c
src/main/cpp/libopus/src/opus_multistream.c
src/main/cpp/libopus/src/opus_encoder.c
src/main/cpp/libopus/celt/celt_encoder.c
src/main/cpp/libopus/celt/bands.c
src/main/cpp/libopus/celt/entcode.c
src/main/cpp/libopus/celt/entdec.c
src/main/cpp/libopus/celt/entenc.c
src/main/cpp/libopus/celt/mathops.c
src/main/cpp/libopus/celt/vq.c
src/main/cpp/libopus/celt/cwrs.c
src/main/cpp/libopus/celt/celt.c
src/main/cpp/libopus/celt/mdct.c
src/main/cpp/libopus/celt/kiss_fft.c
src/main/cpp/libopus/celt/bands.c
src/main/cpp/libopus/celt/pitch.c
src/main/cpp/libopus/celt/celt_lpc.c
src/main/cpp/libopus/celt/quant_bands.c
src/main/cpp/libopus/celt/laplace.c
src/main/cpp/libopus/celt/modes.c
src/main/cpp/libopus/celt/rate.c
src/main/cpp/libopus/silk/lin2log.c
src/main/cpp/libopus/silk/enc_API.c
src/main/cpp/libopus/silk/resampler.c
src/main/cpp/libopus/silk/resampler_private_IIR_FIR.c
src/main/cpp/libopus/silk/resampler_private_up2_HQ.c
src/main/cpp/libopus/silk/resampler_private_down_FIR.c
src/main/cpp/libopus/silk/resampler_private_AR2.c
src/main/cpp/libopus/silk/resampler_rom.c
src/main/cpp/libopus/silk/float/encode_frame_FLP.c
src/main/cpp/libopus/silk/gain_quant.c
src/main/cpp/libopus/silk/log2lin.c
src/main/cpp/libopus/silk/encode_pulses.c
src/main/cpp/libopus/silk/code_signs.c
src/main/cpp/libopus/silk/tables_pulses_per_block.c
src/main/cpp/libopus/silk/tables_other.c
src/main/cpp/libopus/silk/shell_coder.c
src/main/cpp/libopus/silk/encode_indices.c
src/main/cpp/libopus/silk/tables_LTP.c
src/main/cpp/libopus/silk/tables_pitch_lag.c
src/main/cpp/libopus/silk/NLSF_unpack.c
src/main/cpp/libopus/silk/tables_gain.c
src/main/cpp/libopus/silk/float/wrappers_FLP.c
src/main/cpp/libopus/silk/quant_LTP_gains.c
src/main/cpp/libopus/silk/VQ_WMat_EC.c
src/main/cpp/libopus/silk/NSQ.c
src/main/cpp/libopus/silk/LPC_analysis_filter.c
src/main/cpp/libopus/silk/NSQ_del_dec.c
src/main/cpp/libopus/silk/process_NLSFs.c
src/main/cpp/libopus/silk/NLSF2A.c
src/main/cpp/libopus/silk/bwexpander_32.c
src/main/cpp/libopus/silk/LPC_inv_pred_gain.c
src/main/cpp/libopus/silk/table_LSF_cos.c
src/main/cpp/libopus/silk/NLSF_encode.c
src/main/cpp/libopus/silk/NLSF_decode.c
src/main/cpp/libopus/silk/NLSF_stabilize.c
src/main/cpp/libopus/silk/sort.c
src/main/cpp/libopus/silk/NLSF_VQ_weights_laroia.c
src/main/cpp/libopus/silk/NLSF_del_dec_quant.c
src/main/cpp/libopus/silk/NLSF_VQ.c
src/main/cpp/libopus/silk/interpolate.c
src/main/cpp/libopus/silk/float/wrappers_FLP.c
src/main/cpp/libopus/silk/A2NLSF.c
src/main/cpp/libopus/silk/float/process_gains_FLP.c
src/main/cpp/libopus/silk/float/find_pred_coefs_FLP.c
src/main/cpp/libopus/silk/float/residual_energy_FLP.c
src/main/cpp/libopus/silk/float/energy_FLP.c
src/main/cpp/libopus/silk/float/LPC_analysis_filter_FLP.c
src/main/cpp/libopus/silk/float/find_LPC_FLP.c
src/main/cpp/libopus/silk/float/burg_modified_FLP.c
src/main/cpp/libopus/silk/float/inner_product_FLP.c
src/main/cpp/libopus/silk/float/scale_copy_vector_FLP.c
src/main/cpp/libopus/silk/float/LTP_analysis_filter_FLP.c
src/main/cpp/libopus/silk/float/LTP_scale_ctrl_FLP.c
src/main/cpp/libopus/silk/float/find_LTP_FLP.c
src/main/cpp/libopus/silk/float/scale_vector_FLP.c
src/main/cpp/libopus/silk/float/regularize_correlations_FLP.c
src/main/cpp/libopus/silk/float/corrMatrix_FLP.c
src/main/cpp/libopus/silk/float/noise_shape_analysis_FLP.c
src/main/cpp/libopus/silk/float/bwexpander_FLP.c
src/main/cpp/libopus/silk/float/LPC_inv_pred_gain_FLP.c
src/main/cpp/libopus/silk/float/autocorrelation_FLP.c
src/main/cpp/libopus/silk/float/warped_autocorrelation_FLP.c
src/main/cpp/libopus/silk/float/apply_sine_window_FLP.c
src/main/cpp/libopus/silk/float/find_pitch_lags_FLP.c
src/main/cpp/libopus/silk/float/pitch_analysis_core_FLP.c
src/main/cpp/libopus/silk/pitch_est_tables.c
src/main/cpp/libopus/silk/float/sort_FLP.c
src/main/cpp/libopus/silk/resampler_down2.c
src/main/cpp/libopus/silk/resampler_down2_3.c
src/main/cpp/libopus/silk/float/k2a_FLP.c
src/main/cpp/libopus/silk/float/schur_FLP.c
src/main/cpp/libopus/silk/LP_variable_cutoff.c
src/main/cpp/libopus/silk/biquad_alt.c
src/main/cpp/libopus/silk/VAD.c
src/main/cpp/libopus/silk/sigm_Q15.c
src/main/cpp/libopus/silk/ana_filt_bank_1.c
src/main/cpp/libopus/silk/control_SNR.c
src/main/cpp/libopus/silk/stereo_encode_pred.c
src/main/cpp/libopus/silk/stereo_LR_to_MS.c
src/main/cpp/libopus/silk/stereo_quant_pred.c
src/main/cpp/libopus/silk/stereo_find_predictor.c
src/main/cpp/libopus/silk/inner_prod_aligned.c
src/main/cpp/libopus/silk/sum_sqr_shift.c
src/main/cpp/libopus/silk/HP_variable_cutoff.c
src/main/cpp/libopus/silk/control_codec.c
src/main/cpp/libopus/silk/tables_NLSF_CB_NB_MB.c
src/main/cpp/libopus/silk/tables_NLSF_CB_WB.c
src/main/cpp/libopus/silk/control_audio_bandwidth.c
src/main/cpp/libopus/silk/init_encoder.c
src/main/cpp/libopus/silk/check_control_input.c
src/main/cpp/libopus/src/analysis.c
src/main/cpp/libopus/src/repacketizer.c
src/main/cpp/libopus/src/opus.c
src/main/cpp/libopus/src/opus_decoder.c
src/main/cpp/libopus/src/opus_projection_encoder.c
src/main/cpp/libopus/src/opus_projection_decoder.c
src/main/cpp/libopus/src/mapping_matrix.c
src/main/cpp/libopus/src/mapping_matrix.h
src/main/cpp/libopus/celt/celt_decoder.c
src/main/cpp/libopus/silk/dec_API.c
src/main/cpp/libopus/silk/stereo_MS_to_LR.c
src/main/cpp/libopus/silk/decode_frame.c
src/main/cpp/libopus/silk/PLC.c
src/main/cpp/libopus/silk/bwexpander.c
src/main/cpp/libopus/silk/CNG.c
src/main/cpp/libopus/silk/decode_core.c
src/main/cpp/libopus/silk/decode_parameters.c
src/main/cpp/libopus/silk/decode_pitch.c
src/main/cpp/libopus/silk/decode_pulses.c
src/main/cpp/libopus/silk/decode_indices.c
src/main/cpp/libopus/silk/stereo_decode_pred.c
src/main/cpp/libopus/silk/decoder_set_fs.c
src/main/cpp/libopus/silk/init_decoder.c
src/main/cpp/libopus/src/mlp.c
src/main/cpp/libopus/src/mlp_data.c
src/main/cpp/libopus/silk/LPC_fit.c
)
find_library(
log-lib
log)
find_library(android-lib
android)
target_link_libraries(
opusutil-lib
${log-lib}
${android-lib}
)
add_definitions(-DOUTSIDE_SPEEX -DOPUS_BUILD -DSTDC_HEADERS -DVAR_ARRAYS)最终目录结构如下图:
接下来在jni文件下编写编解码实现
实现编码函数
创建编码器:
static jlong
createOpusEncoder(JNIEnv *env, jobject thiz, jint sampleRateInHz, jint channelConfig, jint bitrate,
jint complexity) {
int error;
//通过采样率,声道数创建编码器
OpusEncoder *pOpusEnc = opus_encoder_create(sampleRateInHz, channelConfig,
OPUS_APPLICATION_RESTRICTED_LOWDELAY,
&error);
if (pOpusEnc) {
//设置是否动态码率
opus_encoder_ctl(pOpusEnc, OPUS_SET_VBR(0));//0:CBR, 1:VBR
opus_encoder_ctl(pOpusEnc, OPUS_SET_VBR_CONSTRAINT(true));
//设置码率值(码率是bitspresecond)
opus_encoder_ctl(pOpusEnc, OPUS_SET_BITRATE(bitrate * 1000));
//设置复杂度
opus_encoder_ctl(pOpusEnc, OPUS_SET_COMPLEXITY(complexity));//8 0~10
设置SIGNAl
opus_encoder_ctl(pOpusEnc, OPUS_SET_SIGNAL(OPUS_SIGNAL_VOICE));
opus_encoder_ctl(pOpusEnc, OPUS_SET_LSB_DEPTH(16));
opus_encoder_ctl(pOpusEnc, OPUS_SET_DTX(0));
opus_encoder_ctl(pOpusEnc, OPUS_SET_INBAND_FEC(0));
opus_encoder_ctl(pOpusEnc, OPUS_SET_PACKET_LOSS_PERC(0));
}
return (jlong) pOpusEnc;
}编码一帧数据:
//输入short数组的pcm数据samples,输出编码后的byte数组 bytes
static jint encodeOpus
(JNIEnv *env, jobject thiz, jlong pOpusEnc, jshortArray samples, jint offset,
jbyteArray bytes) {
OpusEncoder *pEnc = (OpusEncoder *) pOpusEnc;
if (!pEnc || !samples || !bytes)
return 0;
jshort *pSamples = (*env)->GetShortArrayElements(env, samples, 0);
jsize nSampleSize = (*env)->GetArrayLength(env, samples);
jbyte *pBytes = (*env)->GetByteArrayElements(env, bytes, 0);
jsize nByteSize = (*env)->GetArrayLength(env, bytes);
if (nSampleSize - offset < 320 || nByteSize <= 0)
return 0;
//编码一帧数据,返回编码完成后的数据大小
int nRet = opus_encode(pEnc, pSamples + offset, nSampleSize, (unsigned char *) pBytes,
nByteSize);
(*env)->ReleaseShortArrayElements(env, samples, pSamples, 0);
(*env)->ReleaseByteArrayElements(env, bytes, pBytes, 0);
return nRet;
}销毁编码器
static void destroyOpusEncoder
(JNIEnv *env, jobject thiz, jlong pOpusEnc) {
OpusEncoder *pEnc = (OpusEncoder *) pOpusEnc;
if (!pEnc)
return;
opus_encoder_destroy(pEnc);
}封装编解码函数根据前面减少API的文章比较容易实现,采集调用模块有些需要注意事项,下面我们实现
采集模块
利用Android的AudioRecorder模块读取PCM数据,AudioRecorder对每次读取的内容有最小长度限制,通过AudioRecord.getMinBufferSize计算得到.
构造一个Runnable,在构造方法中计算出每次读取最小长度,并且计算出一帧大小,前面文章Opus从入门到精通(二):编解码器使用提到过OPUS一帧必须为2.5ms, 5ms, 10ms, 20ms, 40ms 或60ms,一帧越小在实时语音中延迟越低,我们取一帧20ms,计算出一帧大小:
this.opusAudioOpusPath = opusAudioOpusPath;
bufferSize = AudioRecord.getMinBufferSize(Constants.DEFAULT_AUDIO_SAMPLE_RATE,
channelConfig, AudioFormat.ENCODING_PCM_16BIT) + 2048;
audioBuffer = new byte[bufferSize];
audioRecord =
new AudioRecord(MediaRecorder.AudioSource.MIC, Constants.DEFAULT_AUDIO_SAMPLE_RATE,
channelConfig, AudioFormat.ENCODING_PCM_16BIT, bufferSize);
bytesPerTenMS =
Constants.DEFAULT_AUDIO_SAMPLE_RATE * 2 * Constants.DEFAULT_OPUS_CHANNEL / 100 * 2;//每次处理20ms
Log.i(TAG, "bytesPerTenMs:" + bytesPerTenMS);
mRemainBuf = new byte[bytesPerTenMS];
mRemainSize = 0;在run 方法中我们循环读取麦克风数据,进行编码:
isRecorder = true;
audioRecord.startRecording();
File file = new File(opusAudioOpusPath);
File fileDir = new File(file.getParent());
if (!fileDir.exists()) {
fileDir.mkdirs();
}
if (file.exists()) {
file.delete();
}
long createEncoder = 0;
FileOutputStream fileOutputStream = null;
BufferedOutputStream fileOpusBufferedOutputStream = null;
try {
file.createNewFile();
fileOutputStream = new FileOutputStream(file, true);
fileOpusBufferedOutputStream = new BufferedOutputStream(fileOutputStream);
createEncoder = OpusUtil._createOpusEncoder(Constants.DEFAULT_AUDIO_SAMPLE_RATE,
Constants.DEFAULT_OPUS_CHANNEL, 16, 3);
Log.i(TAG, "bufferSize:" + bufferSize);
while (isRecorder) {
int curShortSize = audioRecord.read(audioBuffer, 0, bufferSize);
if (curShortSize > 0 && curShortSize <= bufferSize) {
encodeData(createEncoder, fileOpusBufferedOutputStream, curShortSize);
}
}
} catch (IOException e) {
e.printStackTrace();
Log.e(TAG, "e = " + e.getMessage());
} finally {
OpusUtil._destroyOpusEncoder(createEncoder);
audioRecord.stop();
audioRecord.release();
try {
if(fileOpusBufferedOutputStream != null) {
fileOpusBufferedOutputStream.close();
}
} catch (IOException e) {
e.printStackTrace();
}
try {
if(fileOutputStream != null) {
fileOutputStream.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}真正的encodeData内容:
private void encodeData(long createEncoder, BufferedOutputStream fileOpusBufferedOutputStream,
int readSize) throws IOException {
byte []data = audioBuffer;
if (mRemainSize > 0) {
byte totalBuf[] = new byte[readSize + mRemainSize];
System.arraycopy(mRemainBuf, 0, totalBuf, 0, mRemainSize);
System.arraycopy(data, 0, totalBuf, mRemainSize, readSize);
data = totalBuf;
readSize += mRemainSize;
mRemainSize = 0;
}
int hasHandleSize = 0;
while (hasHandleSize < readSize) {
int readCount = bytesPerTenMS;
if (bytesPerTenMS > readSize) {
Log.i(TAG, "bytesPerTenMs > readSize");
mRemainSize = readSize;
System.arraycopy(data, 0, mRemainBuf, 0, readSize);
return;
}
if ((readSize - hasHandleSize) < readCount) {
mRemainSize = readSize - hasHandleSize;
Log.d(TAG, "remain size :" + mRemainSize);
System.arraycopy(data, hasHandleSize, mRemainBuf, 0, mRemainSize);
return;
}
byte[] bytes = new byte[readCount];
System.arraycopy(data, hasHandleSize, bytes, 0, readCount);
short[] leftData = ArrayUtil.bytes2shorts(bytes, readCount);
byte[] decodedData = new byte[readCount];
int encodeSize = OpusUtil._encodeOpus(createEncoder, leftData, 0, decodedData);
Log.d(TAG, "encodeSize = " + encodeSize);
if (encodeSize > 0) {
byte[] decodeArray = new byte[encodeSize];
System.arraycopy(decodeArray, 0, decodedData, 0, encodeSize);
fileOpusBufferedOutputStream.write(decodeArray);
} else {
return;
}
hasHandleSize += readCount;
}
}这里面需要注意的是encodeData时,因为每次从麦克风读取的数据并不是正好等于一帧,所以我们需要首先判断当前读到的数据是否大于一帧,如果大于一帧则需要循环一帧一帧解码,当循环到最后一次不足一帧时,我们把当前数据缓存起来,和下次从麦克风读取到的数据合并到一起后再进行处理.否则把随意的数据扔到解码器中,解码器会报错.
使用华为荣耀8采集,16k采样,AudioRecord.getMinBufferSize结果为1280,加了2048后变成了3328.
源码地址:https://github.com/qingkouwei/AndroidOpusTools
IOS平台编码程序实现
IOS平台的编码过程与Android大同小异,都是需要注意每帧大小.IOS使用AVAudioRecorder将语音录制成WAV,然后再通过循环读取WAV中PCM数据进行编码.
@property (nonatomic, strong) AVAudioSession *audioSession;
@property (nonatomic, strong) AVAudioRecorder *audioRecorder;
@implementation AudioManager {
dispatch_queue_t queue;
void (^_recordProcessHandler)(float volume);
void (^_recordCompletedHandler)(NSData *data, NSError *error);
}
- (void)recordStartWithProcess:(void (^)(float peakPower))processHandler
completed:(void (^)(NSData *data, NSError *error))completedHandler {
dispatch_async(queue, ^{
if (!self.audioRecorder.isRecording) {
self->_recordProcessHandler = processHandler;
self->_recordCompletedHandler = completedHandler;
[self.audioRecorder prepareToRecord];
[self.audioRecorder record];
self->_timer.fireDate = [NSDate distantPast];
} else {
if (completedHandler) {
NSError *error = [NSError errorWithDomain:@"AudioManager" code:-1 userInfo:@{@"info": @"audio recorder is running."}];
dispatch_async(dispatch_get_main_queue(), ^{
completedHandler(nil, error);
});
}
}
});
}
- (void)audioRecorderDidFinishRecording:(AVAudioRecorder *)recorder successfully:(BOOL)flag {
if (_recordCompletedHandler) {
if (flag) {
NSData *data = [[NSData alloc] initWithContentsOfURL:recorder.url];
dispatch_async(dispatch_get_main_queue(), ^{
self->_recordCompletedHandler(data, nil);
});
} else {
NSError *error = [NSError errorWithDomain:@"AudioManager" code:-2 userInfo:@{@"info": @"audio recorder is failed."}];
dispatch_async(dispatch_get_main_queue(), ^{
self->_recordCompletedHandler(nil, error);
});
}
}
}剩下的主要是如何编译OPUS静态库,网上有人写了现成的脚本Opus-iOS
我自己也实现了一个通用的编译C/C++静态库的脚本:https://github.com/qingkouwei/IOSBuildTools
linux平台编码程序实现
cmake工具与Android平台类似,将配置改成可执行程序即可:
add_executable(
opustools
...
)主程序中我们接收两个参数:PCM文件路径与输出OPUS编码后文件路径
int main(int argc, char **argv)
{
FILE *fin;
FILE *fout;
short *in = NULL;
short *out = NULL;
if (argc != 3)
{
fprintf(stderr, "usage: %s <raw opus input> <mp3 output>\n", argv[0]);
return 1;
}
fin = fopen(argv[1], "rb");
if (!fin)
{
fprintf(stderr, "cannot open input file: %s\n", argv[1]);
return 1;
}
fout = fopen(argv[2], "wb");
if (!fout)
{
fprintf(stderr, "cannot open output file: %s\n", argv[2]);
return 1;
}
...
}创建编码器:
int sampleRateInHz = DEFAULT_SAMPLERATEINHz;
int channelConfig = DEFAULT_CHANNELCONFIG;
int bitrate = DEFAULT_BITRATE;
int error;
OpusEncoder *pOpusEnc = opus_encoder_create(sampleRateInHz, channelConfig,
OPUS_APPLICATION_RESTRICTED_LOWDELAY,
&error);
if (pOpusEnc) {
opus_encoder_ctl(pOpusEnc, OPUS_SET_VBR(0));//0:CBR, 1:VBR
opus_encoder_ctl(pOpusEnc, OPUS_SET_VBR_CONSTRAINT(true));
opus_encoder_ctl(pOpusEnc, OPUS_SET_BITRATE( bitrate* 1000));
opus_encoder_ctl(pOpusEnc, OPUS_SET_COMPLEXITY(complexity));//8 0~10
opus_encoder_ctl(pOpusEnc, OPUS_SET_SIGNAL(OPUS_SIGNAL_VOICE));
opus_encoder_ctl(pOpusEnc, OPUS_SET_LSB_DEPTH(16));
opus_encoder_ctl(pOpusEnc, OPUS_SET_DTX(0));
opus_encoder_ctl(pOpusEnc, OPUS_SET_INBAND_FEC(0));
opus_encoder_ctl(pOpusEnc, OPUS_SET_PACKET_LOSS_PERC(0));
}循环解码数据:
unsigned char *out = (short *)malloc(READ_BUFFER_SIZE * sizeof(char));
while (1)
{
unsigned char data[READ_BUFFER_SIZE];
num_read = fread(data, 1, READ_BUFFER_SIZE, fin);
short sData[num_read/2];
memcpy(data , sData, num_read );
if (num_read > 0)
{
int result = opus_encode(pOpusEnc, sData, num_read/2, out,
READ_BUFFER_SIZE * sizeof(char));
if (fwrite(out, 1, result, fout) != (unsigned)(result)){
printf("write error\n",output_samples,result);
goto failure;
}
}
else{
break;
}
}
fclose(fout);
fclose(fin);我们按一帧20ms编码,采样率设置为16k,那么
一帧大小READ_BUFFER_SIZE= 16000 2 / 1000 20 = 640Byte
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android
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