Audio Capture to WAV Files: Developer Implementation Guide¶

Introduction¶

Capturing audio to WAV files is a fundamental requirement for many multimedia applications. This guide provides detailed instructions for implementing audio capture functionality with or without compression in your applications. Whether you're developing in Delphi, C++ MFC, or VB6 using our ActiveX controls, this guide will walk you through the entire process from initial setup to final implementation.

Setting Up Your Development Environment¶

Before you begin implementing audio capture, ensure you have:

Installed the SDK in your development environment
Added the VideoCapture component to your form/project
Set up basic error handling to manage capture exceptions
Configured your application to access audio hardware

Audio Codec Management¶

Retrieving Available Audio Codecs¶

The first step in implementing audio capture is to retrieve a list of available audio codecs on the system. This allows you to present users with codec options or to programmatically select the most appropriate codec for your application's needs.

Delphi Implementation¶

// Iterate through all available audio codecs
for i := 0 to VideoCapture1.Audio_Codecs_GetCount - 1 do
  cbAudioCodec.Items.Add(VideoCapture1.Audio_Codecs_GetItem(i));

C++ MFC Implementation¶

// Get all available audio codecs and populate combo box
for (int i = 0; i < m_VideoCapture.Audio_Codecs_GetCount(); i++) {
  CString codec = m_VideoCapture.Audio_Codecs_GetItem(i);
  m_AudioCodecCombo.AddString(codec);
}

VB6 Implementation¶

' Iterate through all available audio codecs
For i = 0 To VideoCapture1.Audio_Codecs_GetCount - 1
  cboAudioCodec.AddItem VideoCapture1.Audio_Codecs_GetItem(i)
Next i

Selecting an Audio Codec¶

Once you've populated the list of available codecs, you'll need to provide a way to select the desired codec for the audio capture operation. This can be done programmatically or via user selection.

Delphi Implementation¶

// Set the codec based on user selection from combo box
VideoCapture1.Audio_Codec := cbAudioCodec.Items[cbAudioCodec.ItemIndex];

C++ MFC Implementation¶

// Get the selected codec from the combo box
int selectedIndex = m_AudioCodecCombo.GetCurSel();
CString selectedCodec;
m_AudioCodecCombo.GetLBText(selectedIndex, selectedCodec);

// Set the codec
m_VideoCapture.SetAudio_Codec(selectedCodec);

VB6 Implementation¶

' Set the codec based on user selection
VideoCapture1.Audio_Codec = cboAudioCodec.Text

Configuring Audio Parameters¶

Proper audio parameter configuration is crucial for achieving the desired quality and file size balance. The three primary parameters to configure are channels, bits per sample (BPS), and sample rate.

Setting Audio Channels¶

Audio channels determine whether the captured audio is mono (1 channel) or stereo (2 channels). Stereo provides better spatial audio representation but requires more storage space.

Delphi Implementation¶

// Set the number of audio channels (1 for mono, 2 for stereo)
VideoCapture1.Audio_Channels := StrToInt(cbChannels2.Items[cbChannels2.ItemIndex]);

C++ MFC Implementation¶

// Set audio channels (1 for mono, 2 for stereo)
int channels = _ttoi(m_ChannelsCombo.GetSelectedItem());
m_VideoCapture.SetAudio_Channels(channels);

VB6 Implementation¶

' Set audio channels (1 for mono, 2 for stereo)
VideoCapture1.Audio_Channels = CInt(cboChannels.Text)

Configuring Bits Per Sample (BPS)¶

The bits per sample (BPS) setting affects the dynamic range and quality of the audio. Common values include 8, 16, and 24 bits, with higher values providing better quality at the cost of larger file sizes.

Delphi Implementation¶

// Set bits per sample (typically 8, 16, or 24)
VideoCapture1.Audio_BPS := StrToInt(cbBPS2.Items[cbBPS2.ItemIndex]);

C++ MFC Implementation¶

// Set bits per sample
int bps = _ttoi(m_BPSCombo.GetSelectedItem());
m_VideoCapture.SetAudio_BPS(bps);

VB6 Implementation¶

' Set bits per sample
VideoCapture1.Audio_BPS = CInt(cboBPS.Text)

Setting Sample Rate¶

The sample rate determines how many audio samples are captured per second. Common values include 8000 Hz, 44100 Hz (CD quality), and 48000 Hz (professional audio). Higher sample rates capture more high-frequency detail but increase file size.

Delphi Implementation¶

// Set audio sample rate in Hz (common values: 8000, 44100, 48000)
VideoCapture1.Audio_SampleRate := StrToInt(cbSamplerate.Items[cbSamplerate.ItemIndex]);

C++ MFC Implementation¶

// Set sample rate
int sampleRate = _ttoi(m_SampleRateCombo.GetSelectedItem());
m_VideoCapture.SetAudio_SampleRate(sampleRate);

VB6 Implementation¶

' Set sample rate
VideoCapture1.Audio_SampleRate = CInt(cboSampleRate.Text)

Configuring Output Format¶

Selecting PCM/ACM Format¶

The Windows Audio Compression Manager (ACM) supports various audio formats including PCM (uncompressed) and compressed formats. Setting the output format to PCM/ACM enables codec-based compression when a codec other than PCM is selected.

Delphi Implementation¶

// Set output to PCM/ACM format to enable codec-based compression
VideoCapture1.OutputFormat := Format_PCM_ACM;

C++ MFC Implementation¶

// Set output format to PCM/ACM
m_VideoCapture.SetOutputFormat(Format_PCM_ACM);

VB6 Implementation¶

' Set output format to PCM/ACM
VideoCapture1.OutputFormat = Format_PCM_ACM

Setting the Audio Capture Mode¶

Before starting the capture operation, you need to set the component to audio capture mode. This ensures that only audio is captured without any video streams.

Delphi Implementation¶

// Set to audio-only capture mode
VideoCapture1.Mode := Mode_Audio_Capture;

C++ MFC Implementation¶

// Set to audio-only capture mode
m_VideoCapture.SetMode(Mode_Audio_Capture);

VB6 Implementation¶

' Set to audio-only capture mode
VideoCapture1.Mode = Mode_Audio_Capture

Starting the Audio Capture¶

With all parameters configured, you can now start the audio capture process. This initializes the audio hardware, applies the selected codec and settings, and begins capturing audio to the specified output file.

Delphi Implementation¶

// Begin audio capture process
VideoCapture1.Start;

C++ MFC Implementation¶

// Begin audio capture process
m_VideoCapture.Start();

VB6 Implementation¶

' Begin audio capture process
VideoCapture1.Start

Advanced Implementation Considerations¶

User Interface Integration¶

To provide a better user experience, consider implementing:

Real-time audio level metering
Elapsed time display
File size estimation
Pause/resume functionality

Performance Optimization¶

For optimal performance when capturing extended audio sessions:

Monitor system memory usage
Implement file splitting for long recordings
Consider buffering strategies for high-quality captures

Troubleshooting Common Issues¶

When implementing audio capture, you might encounter these common issues:

No audio devices detected: Ensure proper hardware connections and drivers
Poor audio quality: Verify sample rate and bits per sample settings
Codec compatibility issues: Test with standard codecs like PCM or MP3
High CPU usage: Consider reducing sample rate or using hardware acceleration

Conclusion¶

Implementing audio capture to WAV files in your applications requires careful configuration of codecs, audio parameters, and output settings. By following this guide, you can create robust audio capture functionality that balances quality and file size requirements.

For complex implementations or specific technical challenges, our support team is available to assist with custom solutions tailored to your application requirements.

Additional Resources¶

Visit our GitHub page for more code samples and implementation examples that demonstrate advanced audio capture techniques and integration patterns.

For technical assistance with this implementation, please contact our support team. Additional code samples are available on our GitHub page.