Reference Signal Source: audio as Media Foundation source

Reference signal source for DirectShow in its video part already received Media Foundation Source interface earlier.

This time, the update implements a separate Media Foundation source for audio. MfGenerate2 sample code gives an idea on how to initialize the source:

using namespace AlaxInfoDirectShowReferenceSource;
CComPtr<IAudioMediaSource> pSource;
__C(pSource->SetMediaType(NULL, g_nSampleRate, g_nChannelCount, g_nBitDepth));
__C(pSource->put_Duration((DOUBLE) g_nDuration));
CComPtr<IMFMediaSource> pAudioMediaSource = pSource;

The source can be given specific format using Media Foundation stream descriptor’s media type handler, or set up via private COM interface.

The source can be given sampling rate, channel count (all channels receive the same signal) and bit depth for PCM audio formats (8, 16..32), or 32-bit IEEE floating point format.

Video and audio streams can also be combined into aggregate source (video+audio) to produce a multi-track output. The MfGenerate2 sample shows the approach as well:

__D(pVideoMediaSource || pAudioMediaSource, E_UNNAMED);
if(pVideoMediaSource && pAudioMediaSource)
    CComPtr<IMFCollection> pCollection;
    __C(MFCreateAggregateSource(pCollection, &pMediaSource));
} else
    pMediaSource = pVideoMediaSource ? pVideoMediaSource : pAudioMediaSource;

The sample project is capable to produce output of this kind:

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