{"id":1553,"date":"2015-10-10T21:25:14","date_gmt":"2015-10-10T19:25:14","guid":{"rendered":"https:\/\/alax.info\/blog\/?p=1553"},"modified":"2015-10-10T21:25:14","modified_gmt":"2015-10-10T19:25:14","slug":"reference-signal-source-for-directshow","status":"publish","type":"post","link":"https:\/\/alax.info\/blog\/1553","title":{"rendered":"Reference signal source for DirectShow"},"content":{"rendered":"
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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.<\/p>\n

There is of course some content available, and sometimes\u00c2\u00a0<\/span>it’s really nice<\/a>:<\/p>\n

\"Bipbopbipbop<\/a><\/p>\n

However once in a while you need 59.94 fps and not 60, and another time you’d go with 50 so that millisecond time is well-aligned and every second has equal number of frames, then next time you need specific aspect ratio override and then you’d prefer longer clip to a short one.<\/p>\n

I converted one of my sources for reference signal into DirectShow filters, which might be used to produce infinite signal, or otherwise they might be used to generate a file of specific format with specific properties.<\/p>\n

The filters are\u00c2\u00a0<\/span>Reference Video Source<\/em>\u00c2\u00a0<\/span>and\u00c2\u00a0<\/span>Reference Audio Source<\/em>, regular filters registered in a separate category (not virtual video\/audio source devices – yet?), available for instantiation programmatically or in GraphStudioNext\/GraphEdit.<\/p>\n

\"DirectShowReferenceSource<\/a><\/p>\n

The filters are in both 32- and 64-bit versions, with hardcoded properties (yet?): 1280×720@50 32-bit RGB for video and 16-bit PCM mono at 48 kHz for audio. Programmatically, however, the filters can be tuned flexibly using\u00c2\u00a0<\/span>IAMStreamConfig::Format<\/code><\/a>\u00c2\u00a0<\/span>call:<\/p>\n