Tag: Audio

Reference Signal Source: audio as Media Foundation source

Posted on July 15, 2017July 13, 2017 by Roman

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.CoCreateInstance(__uuidof(AudioMediaSource))); __C(pSource->SetMediaType(NULL, g_nSampleRate, g_nChannelCount, g_nBitDepth)); __C(pSource->put_Duration((DOUBLE) g_nDuration)); CComPtr<IMFMediaSource> pAudioMediaSource =…

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DirectShowSpy: REGDB_E_CLASSNOTREG with IMMDevice::Activate

Posted on April 21, 2016April 22, 2016 by Roman

A DirectShow developer complained on sudden failure of Core Audio IMMDevice::Activate call supposed to instantiate a DirectShow filter for a given device. The problem appeared to be related to installed DirectShowSpy and its interference with the API calls. The symptom was of the following kind: when Activate was called for different types of objects, the…

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Reference signal source for DirectShow

Posted on October 10, 2015 by Roman

Every so often there are tasks that need certain reference video or video/audio footage with specific properties: resolution, frame rate, frame accuracy with content identifying specific frame, motion in view, amount of motion which is “hard” for processing with encoder tuned for natural video, specific video and audio synchronization. There is of course some content…

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Audio playback at non-standard rates in DirectShow

Posted on April 20, 2014April 20, 2014 by Roman

DirectShow streaming and playback in particular offers flexible playback rates for scenarios where playback is requested to take place slower or faster than real time. For a DirectShow developer, the outer interface is pretty straightforward:IMediaPosition::put_RateÂ takes playback rate and that’s it. Playback rate. Must not be zero. The playback rate is expressed as a ratio of…

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CaptureClock: Utility to Check Video/Audio Capture Rates

Posted on January 4, 2013January 4, 2013 by Roman

Someone discovered the utility while browsing my public repository (the app prompts to post data back to the website, and the anonymous user accepted the offer and posted the report from this unpublished application), so I have to drop a few lines about the tool. The idea is basically straightforward: live capture involves attaching time…

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Sample: Simultaneous Audio Playback via Waveform Audio (waveOut) API

Posted on October 12, 2011October 12, 2011 by Roman

The minimalistic sample demonstrates support of [deprecated] Waveform Audio API for multiple playback streams. Depending on command line parameters, the application starts threads to open audio hardware using separate waveOutOpen call and stream one or more generated sine waves: 1,000 Hz sine wave as 22,050 Hz, Mono, 16-bit PCM (command line parameter “a”) 5,000 Hz…

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Utility Clearance: Enumerate Audio ‘MMDevice’s

Posted on August 30, 2011August 30, 2011 by Roman

The utility and code does straightforward enumeration of MMDevices (Vista+, check MSDN for MMDevice API availability), which correspond to MMDevice API, WASAPI, Core Audio API. The code itself is straightforward, with a ready to use binary to quickly lookup data of interest: The data is detailed well and in Excel-friendly format (via Copy/Paste): The code…

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