将 CELT 音频解码为 WAV

Question

我需要从 CS:GO 游戏服务器中提取语音数据。 引擎给了我压缩音频片段 stream，然后我通过 celt 库 (IVoiceCodec::Decompress) 解压缩，就像在这个源代码中所做的一样： https://github.com/perilouswithadollarsign/cstrike15_src/blob/f82112a2388b841d72cb612ca46fcc188 /engine/audio/private/voice.cpp

该接口没有提供任何有关解码数据的信息，但从源代码中我可以猜测它应该是单通道 16bit/22050KHz PCM 音频

static std::vector<char> buffer;

char decompressedData[MAX_UNCOMPRESSED_VOICE_BUFFER_SIZE];  
const int decompressedBytes = g_pCodec->Decompress(data.data(),
                                                   data.size(),
                                                   decompressedData,
                                                   MAX_UNCOMPRESSED_VOICE_BUFFER_SIZE);

if(decompressedBytes > 0)
    buffer.insert(buffer.end(),
                  decompressedData,
                  decompressedData + decompressedBytes);
        
if(buffer.size() > 50000)
{
    static int fileIndex = 0;
    const std::string fileName("wav/test_" + std::to_string(clientIndex) + "_" + std::to_string(fileIndex) + ".wav");
    const bool result = WriteWaveFile(fileName.c_str(),
                    buffer.data(),
                    buffer.size(),
                    16, // Bits per sample
                    1, // Channels
                    22050 // Samples per sec
                    );
                    
    buffer.clear();
        
    ++fileIndex;
}

解码器工作时没有错误并输出正确的数据（解码后我可以辨认出声音）。 然后我将这些片段保存为单通道 16 位/22050KHz PCM WAV 文件而没有任何更改。 从技术上讲，我在数据前添加了 42 个字节的 WAV header。 然后我合并文件。 这是我得到的示例： https://drive.google.com/file/d/16iSC-GXzzl5wwYsvAQN1Hkk93LuSyRYG/view?usp=share_link音调听起来正确，但播放速度太快，我能听到噪音。

这是我编写wav文件的代码（我也是从引擎源代码中得到的）：

void WriteDWord(FileHandle_t fp, unsigned long val) 
{
    g_pFileSystem->Write(&val, 4, fp);
}

void WriteWord(FileHandle_t fp, unsigned short val) 
{
    g_pFileSystem->Write(&val, 2, fp);
}

bool WriteWaveFile(
    const char *pFilename, 
    const char *pData, 
    int nBytes, 
    int wBitsPerSample, 
    int nChannels, 
    int nSamplesPerSec)
{
    FileHandle_t fp = g_pFileSystem->Open(pFilename, "wb");
    if(!fp)
        return false;

    // Write the RIFF chunk.
    g_pFileSystem->Write("RIFF", 4, fp);
    WriteDWord(fp, 0);
    g_pFileSystem->Write("WAVE", 4, fp);


    // Write the FORMAT chunk.
    g_pFileSystem->Write("fmt ", 4, fp);

    WriteDWord(fp, 0x10);
    WriteWord(fp, WAVE_FORMAT_PCM);
    WriteWord(fp, (unsigned short)nChannels);   
    WriteDWord(fp, (unsigned long)nSamplesPerSec);
    WriteDWord(fp, (unsigned long)((wBitsPerSample / 8) * nChannels * nSamplesPerSec));
    WriteWord(fp, (unsigned short)((wBitsPerSample / 8) * nChannels));
    WriteWord(fp, (unsigned long)wBitsPerSample);

    // Write the DATA chunk.
    g_pFileSystem->Write("data", 4, fp);
    WriteDWord(fp, (unsigned long)nBytes);
    g_pFileSystem->Write(pData, nBytes, fp);

    // Go back and write the length of the riff file.
    unsigned long dwVal = g_pFileSystem->Tell(fp) - 8;
    g_pFileSystem->Seek(fp, 4, FILESYSTEM_SEEK_HEAD);
    WriteDWord(fp, dwVal);

    g_pFileSystem->Close(fp);
    return true;
}

我尝试更改采样率和每个样本的位数，但仍然得到错误的结果。 wav 文件有什么问题？

Answer 1

IVoiceCodec::Decompress 似乎返回样本数而不是写入的字节数。