A source that documents itself through a specific downstream node depends on
that node to be understood, and that node already depends on this one for
frames. The README pointed at one by name and the CI workflow still carried a
comment about the dataflow that wired it, which no longer exists.
The output is documented by its type instead: wire `image` into anything that
takes std/media/v1/Image. PREVIEW covers seeing the frames without naming
anyone. Generic words like "a viewer" or "a consumer" stay, since they describe
a role rather than a repository.
Captures frames from a V4L2 camera and publishes them as std/media/v1/Image:
an Arrow struct of width, height, encoding and data, so a receiver needs
nothing from the message metadata. For a compressed encoding the recorded
dimensions are the image's, not the length of the payload.
Based on opencv-video-capture from dora-hub, with three changes. The output is
the typed image struct rather than a flat UInt8 buffer plus metadata. Camera
selection by id reads /dev/v4l/by-id/ only; the upstream macOS system_profiler
and Windows PowerShell enumeration is not carried. CAPTURE_FRAMES bounds a run
so a test ends on its own, in place of upstream's ten-second CI cutoff -- a
timeout would have made the CI step exit non-zero.
CI=true keeps a failed capture from raising, publishing a labelled black frame
instead, which is what lets dataflow.yml run on a machine with no camera.
Two dataflows, run one at a time, as dora has no cross-dataflow wiring:
dataflow.yml is the camera alone and the CI gate; dataflow_view.yml wires it
into dora-image-view and is not run by CI, since it fetches that node over the
network and needs a tag to exist there.
cristhian