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Assemble camera images into an MP4 video

Source: R/make_video.R
make_video.Rd

Downloads images for a camera over a specified time range and encodes them into an MP4 video using the av package. Provide either cam_id or site_id to identify the camera, and use time to restrict the range.

Usage

make_video(
  cam_id = NULL,
  site_id = NULL,
  time = NULL,
  output = NULL,
  fps = 2,
  size = "small",
  limit = 1000L,
  dir = NULL,
  one_per_day = FALSE
)

Arguments

cam_id

Character. Camera identifier. Cannot be used with site_id.

site_id

Character. NWIS site number (e.g. "05366800" or "USGS-05366800"). Cannot be used with cam_id.

time

POSIXct, Date, or character vector of length 1 or 2. Same semantics as download_images(). When dir is supplied, timestamps are parsed from the filenames (NIMS format: <camId>___<timestamp>.jpg).

output

Character. File path for the output MP4. Defaults to "<cam_id>.mp4" (or "<site_id>.mp4", or the directory basename) in the working directory.

fps

Positive number. Frames per second. Any positive value is accepted. Default is 2.

size

Image size passed to download_images(). One of "small" (default), "overlay", or "thumb". Ignored when dir is supplied.

limit

Integer. Page size for the internal list_images() call. Default is 1000. Ignored when dir is supplied.

dir

Character. Path to a local directory of already-downloaded images. When supplied, downloads are skipped and JPEG/PNG files are read from this directory. cam_id/site_id and time still apply as filters.

one_per_day

Logical. If TRUE, reduce frames to one per calendar day by selecting the image whose capture time is closest to noon in the camera's local timezone (from the tz field of find_cameras()). Default is FALSE.

Value

The output file path, invisibly.

Details

When dir is supplied, images are read from that local directory instead of being downloaded. You can still pass cam_id/site_id to select only files belonging to a particular camera (matched by filename prefix) and time to filter by timestamp embedded in the filename — useful when a directory contains images from multiple cameras or a wider date range than needed.

Examples

if (FALSE) { # \dontrun{
# Download and assemble images for a date range
make_video("WI_Chippewa_River_at_Grand_Ave_at_Eau_Claire",
           time = c("2025-06-01", "2025-06-02"), output = "chippewa.mp4")

# One frame per day from a local directory
make_video(cam_id = "NM_Pecos_Web_Camera_near_Roswell",
           time        = c("2023-08-01", "2023-08-31"),
           dir         = "~/Downloads/Pecos",
           one_per_day = TRUE,
           output      = "pecos_august.mp4")
} # }