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bmdVideoInputColorspaceChanged spamming

PostPosted: Fri Jul 31, 2020 2:00 am
by dakahler
With the latest 11.6 drivers, my VideoInputFormatChanged callback is getting spammed with bmdVideoInputColorspaceChanged notifications, even though nothing is changing. This is on a Quad HDMI card. It happens for all 4 inputs, even when there is nothing connected to them.

Re: bmdVideoInputColorspaceChanged spamming

PostPosted: Tue Aug 04, 2020 12:17 am
by Cameron Nichols
Hi David,

Desktop Video 11.6 introduces a number of new format detection flags for color bit-depth of the incoming signal (ref DeckLink SDK manual - 3.26 Detected Video Input Format Flags):
  • bmdDetectedVideoInput12BitDepth
  • bmdDetectedVideoInput10BitDepth
  • bmdDetectedVideoInput8BitDepth
The bmdVideoInputColorspaceChanged format changed event flag will occur if either the colorspace and/or bit-depth of the detected signal does not match that of the pixel format set on call to IDeckLinkInput::EnableVideoInput.

The Desktop Video SDK samples were updated in 11.6 to prevent persistent IDeckLinkInputCallback::VideoInputFormatChanged callbacks with one of 2 strategies:
  1. For CapturePreview/QuadPreview samples, the VideoInputFormatChanged callback will honor the BMDDetectedVideoInputFormatFlags and enable vide input with a pixel format that matches the flags.
  2. For samples that rely on specific pixel formats, such as FileCapture/Capture, these maintain local BMDPixelFormat variable based on the detected colorspace and only call EnableVideoInput when colorspace is changed.