ffmpeg-builder/lib/ffmpeg.sh

#!/usr/bin/env bash

get_duration() {
	local file="$1"
	ffprobe \
		-v error \
		-show_entries format=duration \
		-of default=noprint_wrappers=1:nokey=1 \
		"${file}"
}

get_avg_bitrate() {
	local file="$1"
	ffprobe \
		-v error \
		-select_streams v:0 \
		-show_entries format=bit_rate \
		-of default=noprint_wrappers=1:nokey=1 \
		"${file}"
}

split_video() {
	local file="$1"
	local start="$2"
	local time="$3"
	local out="$4"
	ffmpeg \
		-ss "${start}" \
		-i "${file}" \
		-hide_banner \
		-loglevel error \
		-t "${time}" \
		-map 0:v \
		-reset_timestamps 1 \
		-c copy \
		"${out}"
}

get_crop() {
	local file="$1"
	local duration
	duration="$(get_duration "${file}")" || return 1
	# don't care about decimal points
	IFS='.' read -r duration _ <<<"${duration}"
	# get crop value for first half of input
	local timeEnc=$((duration / 2))
	ffmpeg \
		-y \
		-hide_banner \
		-ss 0 \
		-discard 'nokey' \
		-i "${file}" \
		-t "${timeEnc}" \
		-map '0:v:0' \
		-filter:v:0 'cropdetect=limit=100:round=16:skip=2:reset_count=0' \
		-codec:v 'wrapped_avframe' \
		-f 'null' '/dev/null' 2>&1 |
		grep -o crop=.* |
		sort -bh |
		uniq -c |
		sort -bh |
		tail -n1 |
		grep -o "crop=.*"
}

get_stream_codec() {
	local file="$1"
	local stream="$2"
	ffprobe \
		-v error \
		-select_streams "${stream}" \
		-show_entries stream=codec_name \
		-of default=noprint_wrappers=1:nokey=1 \
		"${file}"
}

get_file_format() {
	local file="$1"
	local probe
	probe="$(ffprobe \
		-v error \
		-show_entries format=format_name \
		-of default=noprint_wrappers=1:nokey=1 \
		"${file}")" || return 1
	if line_contains "${probe}" 'matroska'; then
		echo mkv
	else
		echo mp4
	fi
}

get_num_streams() {
	local file="$1"
	local type="${2:-}"
	local select=()

	if [[ ${type} != '' ]]; then
		select=("-select_streams" "${type}")
	fi

	ffprobe \
		-v error "${select[@]}" \
		-show_entries stream=index \
		-of default=noprint_wrappers=1:nokey=1 \
		"${file}"
}

get_num_audio_channels() {
	local file="$1"
	local stream="$2"
	ffprobe \
		-v error \
		-select_streams "${stream}" \
		-show_entries stream=channels \
		-of default=noprint_wrappers=1:nokey=1 \
		"${file}"
}

get_stream_lang() {
	local file="$1"
	local stream="$2"
	ffprobe \
		-v error \
		-select_streams "${stream}" \
		-show_entries stream_tags=language \
		-of default=noprint_wrappers=1:nokey=1 \
		"${file}"
}

gen_video() {
	local outFile="$1"
	local addFlags=()
	shift

	local vf="format=yuv420p10le"
	for arg in "$@"; do
		case "${arg}" in
		'1080p') resolution='1920x1080' ;;
		'2160p') resolution='3840x2160' ;;
		'grain=yes') vf+=",noise=alls=15:allf=t+u" ;;
		'hdr=yes')
			local colorPrimaries='bt2020'
			local colorTrc='smpte2084'
			local colorspace='bt2020nc'
			vf+=",setparams=color_primaries=${colorPrimaries}:color_trc=${colorTrc}:colorspace=${colorspace}"
			addFlags+=(
				-color_primaries "${colorPrimaries}"
				-color_trc "${colorTrc}"
				-colorspace "${colorspace}"
				-metadata:s:v:0 "mastering_display_metadata=G(13250,34500)B(7500,3000)R(34000,16000)WP(15635,16450)L(10000000,1)"
				-metadata:s:v:0 "content_light_level=1000,400"
			)
			;;
		*) echo_fail "bad arg ${arg}" && return 1 ;;
		esac
	done

	echo_if_fail ffmpeg -y \
		-hide_banner \
		-f lavfi \
		-i "testsrc2=size=${resolution}:rate=24:duration=5" \
		-vf "${vf}" \
		-c:v ffv1 \
		-level 3 \
		-g 1 \
		-color_range tv \
		"${addFlags[@]}" \
		"${outFile}"
}