Read Video Files (FFmpeg)

How it fits

Typical backends

Caveats

• I/O contractThe bound slot is a directory whose files are decoded in sorted order; pin it at a single file for a deterministic test.
• LatencyEmission cadence tracks the source's own inter-frame spacing, so clips with constant and with variable frame spacing both play at their authentic timing; rate scales that cadence (greater than one is faster, less than one slower, zero emits as fast as the file decodes). A rate change applies from the current frame onward and never rescales the already-played timeline. A consumer that holds a frame back delays the rest of the clip: the frames after it keep their natural spacing from the moment it leaves, with no catch-up burst, so a stall shifts playback later and drops nothing.
• Parameter interactionA set fps (at least 0.001) caps the output at that many frames per second of clip time, sending the source frame nearest each slot and skipping the rest. The slots are picked on the clip's own timeline, so the frames sent are the same however slowly downstream accepts them, and each keeps its own timestamp. Left unset (Nothing), or set at or above the clip's own frame rate, every frame is sent.
• I/O contractOnly regular files are played. A file that cannot be opened, decodes no frame, stops decoding before its end, or has neither a frame rate nor frame timing to pace it by stops the worker with an error naming that file, and nothing after it plays. A video directory that cannot be listed or holds no file stops it the same way, at start or when rebound at run time.
• I/O contractFrames are emitted in BGR colour order; each timestamp is anchored to host wall-clock at start and then advanced by the source's real inter-frame spacing, giving a monotonic timeline rather than the raw container presentation timestamp.
• Parameter interactionwidth and height left unset (Nothing) keep the source resolution; setting only one rescales the other axis to preserve aspect ratio, while setting both is an explicit stretch to the exact target.
• State lifetimerepeat loops the playlist when on, which is the default; when off the playlist plays exactly once and the output stream then stays open but silent, with no end-of-stream, until the slot is rebound or repeat is switched on, which plays the playlist again. The bound slot, width, height, repeat, rate, and fps are hot-swappable, and changing the slot restarts from the new directory.