R/set_encoders.R

In seankross/ari: Automated R Instructor

get_os <- function() {
  sys_info <- Sys.info()
  os <- tolower(sys_info[["sysname"]])
  return(os)
}

#' Set Default Audio and Video Codecs
#'
#' @param codec The codec to use or get for audio/video.  Uses the
#' `ffmpeg_audio_codec` and `ffmpeg_video_codec` options
#' to store this information.
#' @seealso [ffmpeg_codecs()] for options
#' @return A `NULL` output
#'
#'
#' @rdname codecs
#' @export
#'
#' @examples
#' \dontrun{
#' if (have_ffmpeg_exec()) {
#'   print(ffmpeg_version())
#'   get_audio_codec()
#'   set_audio_codec(codec = "libfdk_aac")
#'   get_audio_codec()
#'   set_audio_codec(codec = "aac")
#'   get_audio_codec()
#' }
#' if (have_ffmpeg_exec()) {
#'   get_video_codec()
#'   set_video_codec(codec = "libx265")
#'   get_video_codec()
#'   set_video_codec(codec = "libx264")
#'   get_video_codec()
#' }
#' ## empty thing
#' if (have_ffmpeg_exec()) {
#'   video_codec_encode("libx264")
#'
#'   audio_codec_encode("aac")
#' }
#' }
set_audio_codec <- function(codec) {
  if (missing(codec)) {
    os <- get_os()
    codec <- switch(os,
                    darwin = "libfdk_aac",
                    windows = "ac3",
                    linux = "aac"
    )
  }
  options(ffmpeg_audio_codec = codec)
}

#' @export
#' @rdname codecs
set_video_codec <- function(codec = "libx264") {
  options(ffmpeg_video_codec = codec)
}

#' @export
#' @rdname codecs
get_audio_codec <- function() {
  codec <- getOption("ffmpeg_audio_codec")
  if (is.null(codec)) {
    os <- get_os()
    res <- ffmpeg_audio_codecs()
    if (is.null(res)) {
      fdk_enabled <- FALSE
    } else {
      fdk_enabled <- grepl("fdk", res[res$codec == "aac", "codec_name"])
    }
    if (fdk_enabled) {
      os_audio_codec <- "libfdk_aac"
    } else {
      os_audio_codec <- "aac"
    }
    codec <- switch(os,
                    darwin = os_audio_codec,
                    windows = "ac3",
                    linux = "aac"
    )
    set_audio_codec(codec = codec)
  }
  return(codec)
}

#' @export
#' @rdname codecs
get_video_codec <- function() {
  codec <- getOption("ffmpeg_video_codec")
  if (is.null(codec)) {
    codec <- "libx264"
    set_video_codec(codec = codec)
  }
  return(codec)
}


#' @rdname codecs
#' @export
audio_codec_encode <- function(codec) {
  res <- ffmpeg_audio_codecs()
  if (is.null(res)) {
    warning("Codec could not be checked")
    return(NA)
  }
  stopifnot(length(codec) == 1)
  res <- res[res$codec %in% codec |
               grepl(codec, res$codec_name), ]
  res$encoding_supported
}

#' @rdname codecs
#' @export
video_codec_encode <- function(codec) {
  res <- ffmpeg_video_codecs()
  if (is.null(res)) {
    warning("Codec could not be checked")
    return(NA)
  }
  stopifnot(length(codec) == 1)
  res <- res[res$codec %in% codec |
               grepl(codec, res$codec_name), ]
  res$encoding_supported
}