add ci2-video-file / i.e. MP4 backend - #31
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Adds a new, purely additive ci2 camera backend (camera/ci2-video-file, --camera-backend video-file) that decodes a video file (MP4, FMF, MKV, ...) directly via the existing media-utils/frame-source crate and plays it back at its own native frame rate, looping by default. This lets strand-cam's live acquisition/processing pipeline run against pre-recorded footage with no camera hardware, v4l2loopback, or nokhwa involved at all. Modeled on ci2-sim's shape: a new CameraBackend::VideoFile enum variant and dispatch arm in strand-cam/src/cli_app.rs, one new workspace member/path dependency, and a strand-cam/Cargo.toml dependency line. No existing backend (ci2-pylon, ci2-vimba, ci2-webcam, ci2-sim) is touched. Also adds a new CamArg::ExecuteCommand(String) variant (strand-cam-remote-control) and its dispatcher in cam_arg_task.rs, letting the BUI trigger a named, backend-defined command via ci2::Camera::command_execute -- used by ci2-video-file's "StartPlayback" command to end a hold on the first frame (STRAND_CAM_VIDEO_FILE_AUTOSTART=false), and by STRAND_CAM_VIDEO_FILE_LOOP/ STRAND_CAM_VIDEO_FILE_DONE_MARKER/STRAND_CAM_VIDEO_FILE_LIMIT_FRAMERATE for play-once, end-of-playback signaling, and pacing overrides respectively -- all documented in ci2-video-file/src/lib.rs's own module docs. Two real bugs were found and fixed while developing this, not just on a happy path: - frame_source::FrameDataSource::average_framerate() only reports a value for video carrying strand-cam's own SEI timing metadata, so it's None for an ordinary MP4 -- a naive 30fps fallback would silently play such a file at the wrong speed. Fixed with a priority order: prefer average_framerate() when present, else estimate fps from two consecutive frames' own presentation timestamps, else a fixed default. - The Instant-based "absolute schedule" pacer (the same idiom ci2-sim uses) blasts through a backlog instead of resyncing if the caller is ever delayed by a downstream stall. Fixed with a resync guard: when the pacer falls more than one frame period behind, it resyncs its schedule origin to "now" instead of dumping the whole backlog at once. Verified: cargo build/clippy/fmt clean; cargo build --release -p strand-cam --no-default-features --features flydra_feat_detect,serve_files succeeds; --list-cameras correctly enumerates a video-file camera (name derived from the file's stem). Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Strengthens the existing module-level doc comments rather than adding a separate README (ci2-pylon, the default backend, has neither a README nor much inline prose, so a README here would be out of parity with it): - New "Starting and stopping playback" section naming all three controls that govern when frames move (acquisition_start/acquisition_stop, VIDEO_FILE_AUTOSTART_ENV, VIDEO_FILE_LOOP_ENV) with cross-references to their existing detailed sections. - The "Pacing" section now explicitly names the GenICam accessor methods (acquisition_frame_rate_enable/set_acquisition_frame_rate_enable, acquisition_frame_rate/set_acquisition_frame_rate) and includes the real-camera-hardware-buffer reasoning for the resync guard, previously only in an inline code comment near next_frame. - acquisition_start/acquisition_stop themselves gain doc comments (they had none at all before), since these are the actual generic start/stop API a dev would reach for first. No behavior change. Verified: cargo fmt/clippy -D warnings/license-check clean, cargo doc shows no new warnings (still only the 3 pre-existing private-intra-doc-link ones, unrelated to this change). Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
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Add MP4 backend, this backend allows one to play a prerecorded MP4 (although it should be able to do other formats I have not tested) as a camera backend. It works best if this is MP4 recroded by strand camera itself. The video can loop or hold the first frame, until it receives a command, it then uses an enviromental variable to indicate it has stopped. Frame rate can also be controlled.