我正试图从存储在SD卡上的wav文件中计算MFCC系数。我正在使用库:https://github.com/dspavankumar/compute-mfcc替代ifstream(C++),同时尝试读取Android中的.wav文件
输入是使用ifstream的wav文件路径。我需要能够根据时间段访问从单个wav文件拆分的不同pcm文件,并计算每个段的MFCC。我无法找到一种方法将这些数据(原始pcm数据)从java类中下载到下面的方法中显示的缓冲区中。 (使用JNI)
int process (std::ifstream &wavFp, std::ofstream &mfcFp) {
// Read the wav header
wavHeader hdr;
int headerSize = sizeof(wavHeader);
wavFp.read((char *) &hdr, headerSize);
// Check audio format
if (hdr.AudioFormat != 1 || hdr.bitsPerSample != 16) {
std::cerr << "Unsupported audio format, use 16 bit PCM Wave" <<
std::endl;
return 1;
}
// Check sampling rate
if (hdr.SamplesPerSec != fs) {
std::cerr << "Sampling rate mismatch: Found " << hdr.SamplesPerSec << " instead of " << fs <<std::endl;
return 1;
}
// Initialise buffer
uint16_t bufferLength = winLengthSamples-frameShiftSamples;
int16_t* buffer = new int16_t[bufferLength];
int bufferBPS = (sizeof buffer[0]);
// Read and set the initial samples
wavFp.read((char *) buffer, bufferLength*bufferBPS);
for (int i=0; i<bufferLength; i++)
prevsamples[i] = buffer[i];
delete [] buffer;
// Recalculate buffer size
bufferLength = frameShiftSamples;
buffer = new int16_t[bufferLength];
// Read data and process each frame
wavFp.read((char *) buffer, bufferLength*bufferBPS);
while (wavFp.gcount() == bufferLength*bufferBPS && !wavFp.eof()) {
mfcFp << processFrame(buffer, bufferLength);
wavFp.read((char *) buffer, bufferLength*bufferBPS);
}
delete [] buffer;
buffer = nullptr;
return 0;
}
`
好像我不能直接从C++库访问SD卡上的wav文件。所以我试图通过一个jbytearray并将其转换为char *使用:
extern "C"
JNIEXPORT void JNICALL
Java_com_example_nikhar_mst04v10_RecordActivity_doMFCC(JNIEnv *env, jobject
instance,
jbyteArray wavBytes_) {
int len = env ->GetArrayLength(wavBytes_);
char* buf = new char[len];
env->GetByteArrayRegion(wavBytes_,0,len, reinterpret_cast<jbyte *>(buf));
// TODO
/* env->ReleaseStringUTFChars(wavPath_, wavPath);
env->ReleaseStringUTFChars(mfccPath_, mfccPath);*/
// Assign variables
int numCepstra = 12;
int numFilters = 40;
int samplingRate = 16000;
int winLength = 25;
int frameShift = 10;
int lowFreq = 50;
int highFreq = samplingRate/2;
// Initialise MFCC class instance
MFCC mfccComputer (samplingRate, numCepstra, winLength, frameShift,
numFilters, lowFreq, highFreq);
mfccComputer.process(buf);
}
但这已失败。任何建议,以我如何可以实现这一目标?
注意:我已经修改了mfccComputer的参数为(const * char wavBytes) – user2654207
*好像我无法访问sd卡上的wav文件*注意:我们在2017年推出了Android 6,并于2015年推出了Android 6,所以您有2年时间才能了解发生了什么变化。这显然是权限问题,而不是ifstreams – Selvin
这是我第一次使用android。它只是为了一个特定的目的,所以即时学习即时通讯 – user2654207