# Convert between different formats.
# By default tries to convert all files.
# Usage: transcode <FORMAT> [FILES]
function transcode() {
	local IFS=$'\n'
	local format=${1}
	local targets=(${@:2})
	[[ "${targets}" = "" ]] && targets=($(_ls_file))

	# Report no format.
	if [[ "${format}" = "" ]] || [[ "${format}" =~ "." ]]; then
		_error "No format specified."
		help transcode
		return 2
	fi

	process() {
		# Define context names and status.
		local from="${target##*.}"
		local to="${format}"
		local output="${target##*/}"
		output="${output%.*}.${to}"

		# Skip if file exists.
		[[ -f "${output}" ]] && { _skip "Already exists."; return 0; }

		# Support multiple inputs.
		[[ "${to}" = "mp3" ]] && from=""
		[[ "${to}" = "flac" ]] && from=""
		[[ "${to}" = "mka" ]] && from=""
		[[ "${to}" = "mkv" ]] && from=""

		# Send convert.
		case "${from}-${to}" in
			"gz-xz"|"tgz-txz")
				_transcode_gz-xz "${target}" "${output}"
				;;
			"xz-gz"|"txz-tgz")
				_transcode_xz-gz "${target}" "${output}"
				;;
			"-mp3")
				_transcode_mp3 "${target}" "${output}"
				;;
			"-flac")
				_transcode_flac "${target}" "${output}"
				;;
			"-mka")
				_transcode_mka "${target}" "${output}"
				;;
			"-mkv")
				_transcode_mkv "${target}" "${output}"
				;;
			*)
				_error "Conversion ${target##*.}-${to} not supported."
				return 1
				;;
		esac
	}

	_iterate_targets process ${targets[@]}
}

function _transcode_gz-xz() {
	[[ -f "${2}" ]] && return 1
	pv "${1}" | gzip -d | xz -9e > "${2}"
}

function _transcode_xz-gz() {
	[[ -f "${2}" ]] && return 1
	pv "${1}" | xz -d | gzip -1 > "${2}"
}

function _transcode_mp3() {
	ffmpeg -n -i "${1}" -c:a libmp3lame -b:a 320k -f mp3 "${2}"
}

function _transcode_flac() {
	ffmpeg -n -i "${1}" -c:a flac -f flac "${2}"
}

function _transcode_mka() {
	local braudio=$(_ffprobe_ba "${1}")
	[[ ${braudio} -gt 128 ]] && braudio=128

	ffmpeg -n -i "${1}" -ac 2 -c:a libopus -b:a ${braudio}k -vn "${2}"
}

function _transcode_mkv() {
	local keyint=$(_ffprobe_keyint "${1}")
	local braudio=$(_ffprobe_ba "${1}")
	[[ ${braudio} -gt 128 ]] && braudio=128

	# ffmpeg -n -i "${1}" -c:a libopus -b:a ${braudio}k -c:v libsvtav1 -crf 30 -svtav1-params "fast-decode=1:tune=0" -preset 8 -pix_fmt yuv420p10le -g ${keyint} -vf "scale=-2:min'(1080,ih)'" "${2}"
	ffmpeg -n -i "${1}" -map 0 -map -v -map V -map -t -c:s srt -ac 2 -c:a libopus -b:a ${braudio}k -c:v libsvtav1 -crf 30 -svtav1-params "tune=0" -pix_fmt yuv420p10le -g ${keyint} -vf "scale=-2:min'(1080,ih)'" "${2}"
}