Prerequisites

What the machine, the cameras and the software environment have to provide. Check this before you install — two of these constraints cannot be worked around later.

• The two things to check first
• Computer hardware
• USB bandwidth and controller topology
• HDMI capture devices
• Cameras
• Displays
• The NVIDIA / NVENC constraint
• Software
• Runtime files that must be present

The two things to check first

Most requirements on this page can be met by buying something or installing something. Two cannot be fixed at the venue, so check them before anything else:

1. Three genuinely independent USB 3.0 host controllers. Not three ports — three controllers. A laptop that routes all three ports through one root hub cannot carry three 1080p60 uncompressed feeds, and no setting changes that. See USB bandwidth.
2. Cameras that output 1080p60 specifically. Not 1080p30, not 1080i60. The pipeline is hard-wired for 60 progressive frames per second. See Cameras.

Computer hardware

The RAM figure is not padding. Three feeds each hold a 520-frame ring of uncompressed 1080p video across multiple channels, held in named shared-memory regions so that capture, motion and videogen can all reach the same frames without copying. That is the design; it is why the pipeline sustains 60 fps on three feeds with CPU-only motion detection.

USB bandwidth and controller topology

How to check

1. Plug in all three capture devices.
2. Open Device Manager → View → Devices by connection.
3. Each capture box should appear under a separate USB xHCI Compliant Host Controller entry.

If two of them share a controller, move one to a different physical port and check again. On many laptops the ports on opposite sides of the chassis are on different controllers while adjacent ports are not.

HDMI capture devices

Three USB 3.0 HDMI-to-USB capture devices are required, one per camera. The project has been tested with USB-A 3.0 capture boxes identifying as USB\VID_345F&PID_2130 (device descriptor USB3. 0 capture). Any UVC-compatible box delivering 1920×1080@60Hz in YUY2 should work, but that chipset is the one the test path covers.

Purchase checklist:

• USB 3.0 host interface (USB-A or USB-C). USB 2.0 cannot carry 1080p60 YUY2 — that is roughly 1.2 Gbps per stream.
• HDMI 1.4 or 2.0 input.
• Advertises 1920×1080 @ 60 Hz in YUY2. Many cheap units advertise 1080p60 but actually deliver 1080p30 or MJPEG. Verify the YUY2 60 Hz mode is really present using the Windows Camera app or captest.exe --list before committing to a model.
• UVC-compliant, no proprietary driver. VDM goes through Windows Media Foundation, which speaks standard UVC. Vendor SDKs are not used and will not help.
• Buy three identical units. Mixing chipsets introduces per-stream timing differences that show up as a growing Δ[0].

Cameras

Three fixed-position cameras with 1080p60 HDMI output. This must be 1080p60 specifically — 1080p30 and 1080i60 will not work, because the pipeline is hard-wired for 60 progressive frames per second.

Position the cameras so coverage overlaps by at least 5 m between adjacent feeds.

Displays

The controller's preview tab, the processes tab and a viewer window are genuinely hard to use crammed onto one screen. The recommended layout is: laptop display for the VDM controller, external monitor 1 for the live viewer doing distance measurement, external monitor 2 for fileviewer reviewing past jumps or for operator notes.

Whatever you use, set big_window_width and big_window_height to match — they ship at 2880×1620 for a specific machine's panel and will be wrong on yours. See Configuration § machine-specific settings.

The NVIDIA / NVENC constraint

An NVIDIA GPU with NVENC support and an R570-or-newer driver is required for hardware H.264 encoding in videogen.exe. Verify the driver with:

nvidia-smi

The Driver Version column must read 570.xx or higher. An older driver fails at the point videogen tries to load the NVENC interface, with a version error of the form Required: 13.0 Found: 12.0.

What degrades without NVENC

NVENC is not load-bearing for the whole system. Only the merge-and-encode path uses the GPU — capture and motion detection are entirely CPU-based and are unaffected. When NVENC is unavailable, or when it is deliberately switched off, the encoder falls back to software H.264 (libx264).

The GPU is also selected by name rather than by index. *capfile_nvenc_gpu_name holds a substring matched against the installed adapters, and capfile_nvenc_gpu_index is -1 meaning resolve from the name. On a new machine the stored name will not match anything and must be re-selected. See Installation § first run.

Software

Bundled runtime libraries

These ship inside the package and are installed alongside the executables. You do not install them separately, but they must end up in the same directory as the binaries:

The version suffixes matter. Mixing generations — an avcodec-61 next to a leftover avutil-58 — produces missing-export errors that read like corruption rather than a version mismatch. Verify-Install.ps1 runs a LoadLibraryEx probe against each DLL, which catches exactly this.

Runtime files that must be present

These are data files, not code, and they must sit in the same directory as the executables:

Optional: sample footage

The capture_20180923 companion package is about 5.57 GiB of recorded hill footage. It is not required to install or run VDM, but it is the only way to exercise the full pipeline — motion detection, triggering, merge and encode — without cameras attached. Budget 6.5 GB free on the destination volume. See Sample footage.