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}"
}