C ++录制音频并压缩到GSM

Question

我正在开发一个C ++程序，该程序可以记录音频并将其压缩为GSM。 我能够录制音频并将原始数据写入文件。 但是我无法使GSM压缩正常工作。 我正在尝试使用在此网站ftp://ftp.cs.cmu.edu/project/fgdata/speech-compression/GSM/gsm_13200bps上找到的压缩源代码。

我认为我的问题是使用gsm_encode（）函数时。 播放此文件时，将压缩数据编码并保存到文件后，听不见。 我知道原始音频数据是正确的，但是压缩音频数据是不正确的。

gsm_encode（）将160个13位样本（作为gsm_signal的符号，至少16位的带符号整数值）的数组编码为33字节的gsm_frame。

这是我的功能，我将数据错误地发送到gsm_encode（）吗？ 还是我的功能还有其他问题？ 谢谢您的帮助 ：）

int CAudioGSM::CompressAudio(unsigned char * pRawBuffer, _int32 uiRawBufferSize, unsigned char  * pCompressedBuffer, _int32 uiCompressedBufferSize)
{
// Note: uiRawBufferSize must be a multiple of 640 (AUDIO_DMA_DESCRITOR_LEN)
if(!pRawBuffer || uiRawBufferSize == 0 || !pCompressedBuffer || uiCompressedBufferSize == 0 ||  uiRawBufferSize % AUDIO_DMA_DESCRITOR_LEN != 0)
{
    return -1; //invalid parameters
}

_int32 uiBytesCompressed = 0; // Number of bytes that have been compressed. At the end of the function this should be equal to iRawBufferSize meaning we have compressed the whole raw buffer
_int32 uiCompBuffOffset = 0; // Offset into the compressed buffer

while(uiBytesCompressed < uiRawBufferSize)
{
    if(uiCompressedBufferSize - uiCompBuffOffset < GSM_OUTPUT_SIZE || uiCompBuffOffset >= uiCompressedBufferSize)
    {
       return -2; // Compressed buffer is too small
    }

    gsm_encode(&m_GSM_EncodeStruture,(long *)pRawBuffer,m_Buffer);
    //Now we need to move the data to compressed buffer
    if(m_bFirstHalfOfBlockRecord)
    {
       //Just copy the data over
       memcpy(&pCompressedBuffer[uiCompBuffOffset],m_Buffer,GSM_OUTPUT_SIZE_FIRST_HALF);
       m_bFirstHalfOfBlockRecord = false;
       uiCompBuffOffset += GSM_OUTPUT_SIZE_FIRST_HALF;
    }
    else
    {
       memcpy(&pCompressedBuffer[uiCompBuffOffset],m_Buffer,GSM_OUTPUT_SIZE);
       m_bFirstHalfOfBlockRecord = true;
       uiCompBuffOffset += GSM_OUTPUT_SIZE;
    }

    uiBytesCompressed += AUDIO_DMA_DESCRITOR_LEN;
}

return uiCompBuffOffset; // Success, we have compressed the buffer return compressed data size
}

Answer 1

没关系，我想通了，pRawBuffer永远不会增加，应该是

gsm_encode(&m_GSM_EncodeStruture,(long *)&pRawBuffer[uiBytesCompressed],m_Buffer);