Voice Recording/Playing back using simple classes

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Introduction

Most of us are familiar with at least one multimedia recording software. Windows has one of the simplest ones: Sound Recorder. In this article I want to introduce some simple but useful classes for recording/playing back of voice that wrap the WAVE APIs.

WAVE APIs

Here is the list of all the Wave APIs that I have used:

Recording

waveInOpen	Open the Wave device for recording.
waveInPrepareHeader	Prepare the Wave header for recording.
waveInAddBuffer	Add buffer
waveInStart	Start recording. Recorded data will be saved in a specified buffer.
waveInUnprepareHeader	After finishing the record process, should un-prepare Wave header.
waveInClose	Close the recording device.

Playing

waveOutOpen	Open the Wave device for playing.
waveOutPrepareHeader	Prepare the Wave header for playing.
waveOutWrite	Play the buffer.
waveOutUnprepareHeader	Un-prepare the Wave header.
waveOutClose	Close the playing device.

As you can see, working with these APIs are straightforward but if you want to skip them and simply do a copy/paste code in your project, my classes are for you.

Here is the definition of the classes:

class CVoiceBase  
{
public:
    
    CString m_result;
    MMRESULT res;
    enum 
    {
        SPS_8K=8000,
        SPS_11K=11025,
        SPS_22K=22050,
        SPS_44K=44100
    };

    enum
    {
        CH_MONO=1,
        CH_STEREO=2
    };

    char* buffer;
    WAVEHDR WaveHeader;
    WAVEFORMATEX PCMfmt;

    void SetFormat(DWORD nSamplesPerSec,  
            WORD  wBitsPerSample,WORD  nChannels);
    BOOL CopyBuffer(LPVOID lpBuffer, DWORD ntime);
    CString GetLastError();
    void GetMMResult(MMRESULT res);
    void DestroyBuffer();
    BOOL PrepareBuffer(DWORD ntime);
    
    CVoiceBase();
    virtual ~CVoiceBase();
};

class CVoiceRecording : public CVoiceBase  
{
public:
    void RecordFinished();
    BOOL IsOpen();
    BOOL Close();
    BOOL Open();    
    BOOL Record();
    
    HWAVEIN hWaveIn;
    
    CVoiceRecording();
    virtual ~CVoiceRecording();
};

class CVoicePlaying : public CVoiceBase  
{
public:
    void PlayFinished();
    BOOL IsOpen();
    BOOL Close();
    BOOL Open();
    BOOL Play();

    HWAVEOUT hWaveOut;

    CVoicePlaying();
    virtual ~CVoicePlaying();
};

Also, for notifying of events, such as finishing recording/playing, I have used two callback functions:

BOOL CALLBACK VoiceWaveInProc(HWAVEIN hwi,       
            UINT uMsg,         
            DWORD dwInstance,  
            DWORD dwParam1,    
            DWORD dwParam2     
                );

BOOL CALLBACK VoiceWaveOutProc(HWAVEOUT hwi,       
            UINT uMsg,         
            DWORD dwInstance,  
            DWORD dwParam1,    
            DWORD dwParam2     
                );

Example

Just declare two variables of type CVoiceRecording and CVoicePlaying. Use SetFormat, PrepareBuffer, Open and Record or Play member functions to work with them:

CVoiceRecording m_Record;
CVoicePlaying m_Play;

m_Record.PrepareBuffer(10);    //prepare buffer for recording 10 seconds.
m_Record.Open();
    
m_Play.PrepareBuffer(10);    //prepare buffer for playing of 10 seconds of data
m_Play.Open();    

if (m_Record.IsOpen())
{
    m_Record.Record();
}

//after finishing the record scenario,
//play the buffer, first copy recorded buffer to m_Play buffer
m_Play.CopyBuffer(m_Record.buffer, 10);
        
if (m_Play.IsOpen())
{
    m_Play.Play();
}

Enjoy!