View Full Version : DFG/MC4 Sync'd capture/save

August 11, 2005, 23:18:42
Hi forum,
I am working with the DFG/MC4 card and currently have 2 analog cameras externally sync'd and want to capture the image data simultaneously into 1 effective image stream. Looking to expand to all 4 channels eventually.
I can capture and display the 2 frame grabber inputs as one, but they are not sync'd. (I split the video from 1 camera into 2 frame grabber channels to observe this).
The imagery is required at 320x240 rgb.
I am trying to determine the best way to do this from reading the examples and manual, but I am not sure.
I was thinking of using a listener for both starting the grabber's simultaneously and then using the frameready event to align the image counts, although the doc's/examples suggest that the frameready event is not always triggered.
Suggestions/sample code on a better approach would be appreciated.
As a side note, my previous experience has been with the MILlite library, but I am moving away from that.

Stefan Geissler
August 17, 2005, 08:26:02
Hello Bruce,

Sorry for the long delay, but your problem is hard to solve. You approach is correct. You may work with the sample types, that are in the membuffer saved, but i am not sure, whether this solves your problem.

August 17, 2005, 18:42:05
Hi Stefan,
I have been playing with the Montivision workbench as well and different filter graphs to see what I get. Nice demo tool to work with actually.
I can sync and merge the frames, and save it as a combined double sized frame, but appear to be getting around 13-14 frames /sec. This is with a single camera split to be the two frame grabber inputs.
If I just save the two image streams separately I can get 28-29 frames/sec each channel into separate files with preview rendering off. May stick to this way for now.
Not comfortable with developing additional filters as my imagery is a color rendering of a 12 bit thermal camera requiring some transformation etc to a non standard format , even with the Montivision SDK. In the future maybe.
Anyways, thought I would ask.

Stefan Geissler
August 18, 2005, 08:34:44
Hi Bruce,

for developing filters for MontiVision, you may look here:

Also writing DirectShow filters looks hard in the first view, but the samples, that come with the DirectShow SDK can easily be enhanced. Some times ago i wrote a red/green 3D image filter. It combines the Y800 input of two b/w cameras to one RGB24 image. The synchronization was a little bit strange, but the results were funny. (I hold the cameras in my hands and looked on the live video. Then i became sick...)