Joining Portaudio and Opus

Joining Portaudio and Opus

本文关键字：Opus and Portaudio Joining      更新时间：2023-10-16

我试图从打开的PortAudio流中获取声音，用opus编码，解码并使用PortAudio再次复制。

我这样做只是作为一个原型，只是试图理解这个系统的机制，所以，没有真正的兴趣遵循这个具体的流程。

问题是，portaudio在OPUS需要帧的地方提供缓冲区。我的想法引导我在portaudio方面: 
err = (Pa_ReadStream(stream, readBuffer, FRAMES_PER_BUFFER));
        if (err = paNoError){
            qDebug()<<"Fail read";
            qDebug()<<Pa_GetErrorText(err);
          // blockingRecord = false;
        }
       while (pos<FRAMES_PER_BUFFER){
            memcpy(frameBuffer,readBuffer+(pos*FRAME_SIZE*NUM_CHANNELS),FRAME_SIZE*CHANNELS);
            compressedSound = om.encodeOpus(frameBuffer);
            unCompressedSound = om.decodeOpus(compressedSound);
            memcpy(readBuffer+(pos*FRAME_SIZE*NUM_CHANNELS),unCompressedSound,FRAME_SIZE*CHANNELS);
            pos++;
        }
        pos = 0;
        err = (Pa_WriteStream(stream, readBuffer, FRAMES_PER_BUFFER));
        if (err != paNoError)
        {
            qDebug() << "FAIL WRITE";
            qDebug()<<Pa_GetErrorText(err);
            //blockingRecord = false;
        }

OPUS端:

unsigned char * OpusManager::encodeOpus(unsigned char *frame){
    memcpy(encoded, frame, FRAME_SIZE*CHANNELS);
    int ret = opus_encode(enc, encoded, FRAME_SIZE, compressed_buffer, encoded_data_size);
    if (ret<0){
        qDebug()<<"Failure while compressing sound";
        return NULL;
    }
    return (compressed_buffer);
}
unsigned char * OpusManager::decodeOpus(unsigned char *frame){
    int ret= opus_decode(dec, frame, encoded_data_size, decoded, FRAME_SIZE, 0);
    if (ret<0){
        qDebug()<<"Failure while decompressing sound";
        return NULL;
    }
    memcpy(uncompressed_buffer, decoded, FRAME_SIZE*CHANNELS);
    return (uncompressed_buffer);
}

没有编码错误和完美的声音。与编码我得到没有错误，直到PA_Writestream调用，在那里我得到一个"输出欠流"PaError。我想采取的框架我实现的方式一定是错误的，但不能找到信息来帮助我这个。

似乎您对Opus' frame_size参数对opus_encode和opus_decode的解释是不正确的。如果我正确理解了你的代码，你记录了一个大小为FRAMES_PER_BUFFER帧的数据包，然后尝试将其转换为N个大小为FRAME_SIZE的数据包。相反，在我看来，Opus想要将FRAMES_PER_BUFFER的数据包转换为具有相同帧数的另一个数据包，并且在这样做时，只使用它的FRAME_SIZE参数作为编码过程的某种质量控制参数。下面你会发现一个完整的样本，我相信你想要的。在encode()/decode()中试试'480'这个神奇的数字，听听音质的变化。

int opusErr;
PaError paErr;
std::string s;
int const channels = 2;
int const bufferSize = 480;
int const sampleRate = 48000;
int const durationSeconds = 5;
opus_int32 enc_bytes;
opus_int32 dec_bytes;
int framesProcessed = 0;
std::vector<unsigned short> captured(bufferSize * channels);
std::vector<unsigned short> decoded(bufferSize * channels);
// * 2: byte count, 16 bit samples
std::vector<unsigned char> encoded(bufferSize * channels * 2);
// initialize opus
OpusEncoder* enc = opus_encoder_create(
    sampleRate, channels, OPUS_APPLICATION_AUDIO, &opusErr);
if (opusErr != OPUS_OK)
{
    std::cout << "opus_encoder_create failed: " << opusErr << "n";
    std::getline(std::cin, s);
    return 1;
}
OpusDecoder* dec = opus_decoder_create(
    sampleRate, channels, &opusErr);
if (opusErr != OPUS_OK)
{
    std::cout << "opus_decoder_create failed: " << opusErr << "n";
    std::getline(std::cin, s);
    return 1;
}
// initialize portaudio
if ((paErr = Pa_Initialize()) != paNoError)
{
    std::cout << "Pa_Initialize failed: " << Pa_GetErrorText(paErr) << "n";
    std::getline(std::cin, s);
    return 1;
}
PaStream* stream = nullptr;
if ((paErr = Pa_OpenDefaultStream(&stream,
      channels, channels, paInt16, sampleRate,
      bufferSize, nullptr, nullptr)) != paNoError)
{
    std::cout << "Pa_OpenDefaultStream failed: " << Pa_GetErrorText(paErr) << "n";
    std::getline(std::cin, s);
    return 1;
}
// start stream
if ((paErr = Pa_StartStream(stream)) != paNoError) 
{
    std::cout << "Pa_StartStream failed: " << Pa_GetErrorText(paErr) << "n";
    std::getline(std::cin, s);
    return 1;
}
// capture, encode, decode & render durationSeconds of audio
while (framesProcessed < sampleRate * durationSeconds)
{
    if ((paErr = Pa_ReadStream(stream, 
        captured.data(), bufferSize)) != paNoError)
    {
        std::cout << "Pa_ReadStream failed: " << Pa_GetErrorText(paErr) << "n";
        std::getline(std::cin, s);
        return 1;
    }
    if ((enc_bytes = opus_encode(enc, reinterpret_cast<opus_int16 const*>(
        captured.data()), 480, encoded.data(), encoded.size())) < 0)
    {
        std::cout << "opus_encode failed: " << enc_bytes << "n";
        std::getline(std::cin, s);
        return 1;
    }
    if ((dec_bytes = opus_decode(dec, encoded.data(), enc_bytes,
        reinterpret_cast<opus_int16*>(decoded.data()), 480, 0)) < 0)
    {
        std::cout << "opus_decode failed: " << dec_bytes << "n";
        std::getline(std::cin, s);
        return 1;
    }
    if ((paErr = Pa_WriteStream(stream, decoded.data(), bufferSize)) != paNoError)
    {
        std::cout << "Pa_WriteStream failed: " << Pa_GetErrorText(paErr) << "n";
        std::getline(std::cin, s);
        return 1;
    }
    framesProcessed += bufferSize;
}
// stop stream
if ((paErr = Pa_StopStream(stream)) != paNoError)
{
    std::cout << "Pa_StopStream failed: " << Pa_GetErrorText(paErr) << "n";
    std::getline(std::cin, s);
    return 1;
}
// cleanup portaudio
if ((paErr = Pa_CloseStream(stream)) != paNoError) 
{
    std::cout << "Pa_CloseStream failed: " << Pa_GetErrorText(paErr) << "n";
    std::getline(std::cin, s);
    return 1;
}
if ((paErr = Pa_Terminate()) != paNoError) 
{
    std::cout << "Pa_Terminate failed: " << Pa_GetErrorText(paErr) << "n";
    std::getline(std::cin, s);
    return 1;
}
// cleanup opus
opus_decoder_destroy(dec);
opus_encoder_destroy(enc);
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