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DE-Server external frame source

ExternalFrameSource.h/.cpp let DE-Server's GrabberSim take camera frames from another process through shared memory. The de-twin digital twin (de-twin serve --shm) is the intended producer. Frames then go through the normal DE-Server pipeline exactly as simulator frames do: frame-number stamp, RevertToCrude, CheckBuffer, references, counting, saving.

What changes in DE-Server

File Change
Grabber/ExternalFrameSource.h/.cpp new, about 220 lines including the layout comments
Grabber/GrabberSim.h include, and one ExternalFrameSource m_externalFrames member
Grabber/GrabberSim.cpp MakeExternalFrameRequest(); Begin() when an acquisition starts; a GenerateFrame branch that reads frames; End() when the acquisition finishes; no frame-time benchmark for this pattern
Camera/Camera.cpp adds the test pattern name to the list
CameraServer.vcxproj(.filters) the two new files

How it works

  1. When an acquisition starts with the test pattern External Frame Source (Shared Memory), GrabberSim creates the shared memory DE_ExternalFrames (first time only). It then writes the request: hw_frame size, bytes per pixel, sensor, hardware ROI and binning, frame time, number of frames (0 = live), exposure mode and scan size. Finally it increments requestId.
  2. The producer fills slots with frames. For each frame of a buffer, GrabberSim calls ReadFrame, which waits for the next frame and copies it into the grab buffer. If no frame arrives within 2 x frame time + 1 s, the frame is left blank and a warning is logged, so acquisitions never hang.
  3. When the acquisition ends, acquiring goes to 0, and the producer stops.

The layout is documented at the top of ExternalFrameSource.h. Its Python mirror is de_twin/transport/shm_layout.py, and tests/test_shm_layout.py checks the two agree against the compiled header.

Running it

  1. In configurations/server.xml, set GrabberType="Software". Any Camera Type works; it sets the sensor size, topology and bit depth.
  2. Start the twin: de-twin serve --shm --soap 5002 --camera DE16. The --soap flag lets DE-Server poll the twin's microscope as its TEM-Channel: set Instrument Client Address to that machine.
  3. In DE-MC, pick the test pattern External Frame Source (Shared Memory) and acquire.

Dark references work because the twin blanks the beam when the request's exposure mode is Dark.

Scan coil voltages

ScanOutput.h (DE-Server's Scanner/ScanOutput.h) is the scan card's side. In simulator mode there is no card, so the scan simulator writes the voltages it would have sent into the shared memory DE_ScanOutput: block by block, with the pixel offset read once per block, and as far ahead of the beam as the card's FIFO would hold (Scan - Output Buffer (milliseconds)). The twin renders each frame where its point's voltages put the beam, so a pixel offset, an XY array or drift correction steers it with the latency a real scan card gives.

File Change
Scanner/ScanOutput.h new: the layout and a small writer
Scanner/ScanController.h/.cpp _SizeOutputBlocks() (the card's block sizing, now shared with the simulator), _BeginSimulatedOutput() when a simulated scan starts, _WriteSimulatedOutputBlock() as the simulator advances

Its Python mirror is de_twin/transport/scan_output.py, checked against the compiled header by tests/test_scan_output.py.

Testing without DE-Server

build.bat builds build\test_consumer.exe from the same ExternalFrameSource.cpp:

  • test_consumer layout prints every struct offset, compared by tests/test_shm_layout.py and tests/test_scan_output.py.
  • test_consumer <mapping> <frames> <w> <h> <exposureMode> acts like DE-Server. The twin's shared-memory face serves it in tests/test_shm_interop.py.