WebM (vp8 / no audio) bash script

webm

#!/usr/bin/env bash


INPUT="${1}"
OUTPUT="${2:-video.webm}"
MAXSIZE="${3:-3}"
START="${4}"
LENGTH="${5}"


if [ $# -eq 0 ]; then
	echo "Create vp8/webm video files without audio:"
	echo "webm input [output [size [start length [...]]]]"
	echo ""
	echo "The existing output file will always be overwritten (default: video.webm)"
	echo "size is set in MiB (25 KiB will be subtracted) (default: 3)"
	echo "start (in secs or timestamp) and length (in secs) need to be set at the same time (default: unset)"
	echo "accepts additional ffmpeg parameters that can be used for scaling, cropping, etc."
	exit 0
fi

if [ ! -f "${INPUT}" ]; then
	>&2 echo "Invalid input file"
	exit 1
fi

for dep in ffmpeg ffprobe jq bc mktemp; do
	if ! which "${dep}" >/dev/null; then
		>&2 echo "Missing dependency ${dep}"
		exit 1
	fi
done


set -e


THRESHOLD=0.025
THREADS=$(grep -c '^processor' /proc/cpuinfo)

if [ -z "${START}" ] || [ -z "${LENGTH}" ]; then
	START="0"
	LENGTH="$(ffprobe -v error -show_format -show_streams -print_format json "${INPUT}" | jq ".format.duration | tonumber")"
fi

BITRATE=$(bc -l <<< "scale=0; ( ${MAXSIZE} - ${THRESHOLD} ) * 8 * 1024 * 1024 / ${LENGTH}")
PASSFILE="$(mktemp)"

(
	set -x

	ffmpeg -hide_banner \
		-i "${INPUT}" \
		-ss "${START}" \
		-t "${LENGTH}" \
		-an \
		-c:v libvpx \
		-b:v "${BITRATE}" \
		"${@:6}" \
		-quality best \
		-threads "${THREADS}" \
		-pass 1 \
		-passlogfile "${PASSFILE}" \
		-f webm \
		-y \
		/dev/null

	ffmpeg -hide_banner \
		-i "${INPUT}" \
		-ss "${START}" \
		-t "${LENGTH}" \
		-an \
		-c:v libvpx \
		-b:v "${BITRATE}" \
		"${@:6}" \
		-quality best \
		-threads "${THREADS}" \
		-pass 2 \
		-passlogfile "${PASSFILE}" \
		-f webm \
		-y \
		"${OUTPUT}"
)

rm "${PASSFILE}-0.log" 2>/dev/null || true