Recording IM application's audio such as Skype, G-Talk or Msn requires the interception of MCI Wave API calls, IDirectSound interface and the new IAudioClient interface, part of the Windows Vista / Windows 7 Core Audio engine. We published a blog article (DirectSound Capture using Deviare) that shows how to record these applications' microphone. This example is focused in microphone capture and it doesn't solve all the problems that you will find when trying to record a conversation (both audio output and microphone together) in a .WAV file.
Capturing microphone and audio output together requires frequency conversion to mix both audio streams. Microphone and audio lines can be in different formats, so it is necessary a frequency conversion to mix them. Finally, to avoid aliasing or to improve sound quality, input and output audio streams should be filtered with a low pass filter. It is very important to maintain code performance because you are processing a real-time audio signal. If special care is not taken, system performance may be degraded and artifacts may appear in the audio signal. Nektra solutions are fast, use low CPU and get the best audio quality. We did a large number of solutions in this topic. Using our wide experience we developed this SDK.
Audio Recording API Features
- Supports Skype (v4.x and v5.x), G-Talk and Msn interception
- Windows XP, Vista, Win7 and W8
- Interception of AudioClient, DirectAudio, Wave API and direct buffer writes
- Notification when a conversation starts and ends
- Single audio stream for both microphone and audio
- Low pass filter increases audio quality
- Low CPU usage
- x86 / x64
- Full source code (Source code version)