R/ffmpeg_convert.R

In seankross/ari: Automated R Instructor

#' Convert Files using FFMPEG
#'
#' @param file Video/PNG file to convert
#' @param outfile output file
#' @param overwrite should output file be overwritten?
#' @param args arguments to pass to \code{\link{system2}} to pass to
#' \code{ffmpeg}
#'
#' @return A character string of the output file with different attributes
#' @export
#'
#' @examples
#' pngfile <- tempfile(fileext = ".png")
#' png(pngfile)
#' plot(0, 0)
#' dev.off()
#' if (have_ffmpeg_exec()) {
#'   res <- ffmpeg_convert(pngfile)
#' }
ffmpeg_convert <- function(file,
                           outfile = tempfile(
                             fileext = paste0(".", tools::file_ext(file))
                           ),
                           overwrite = TRUE,
                           args = NULL) {
  ffmpeg <- ffmpeg_exec(quote = FALSE)
  file <- normalizePath(file)
  add_y <- NULL
  if (file.exists(outfile)) {
    if (!overwrite) {
      stop("outfile already exists, overwrite = FALSE")
    } else {
      add_y <- "-y"
    }
  }
  args <- c(add_y, "-i", file, args, outfile)
  suppressWarnings({
    res <- system2(ffmpeg, args = args, stdout = TRUE, stderr = TRUE)
  })
  attr(outfile, "result") <- res
  return(outfile)
}