Uses ffmpeg to convert ShadowPlay recordings so that they can be uploaded to Discord

8mib.sh

#!/bin/bash
#
# Uses ffmpeg to convert ShadowPlay recordings for uploading to Discord.
# Usage: ./8mib.sh <video_path> [seek_eof]

if [ ! -f "$1" ]; then
    (>&2 echo "The video file could not be found.")
    exit
fi

file_name="${1%.*}"

# 8 mebibytes expressed in bits. 512 bytes leeway for request.
MAX_SIZE=$(( (1024 * 1024 * 8 - 512) * 8 ))

# Sum bitrates of all audio streams.
audio_bitrate="$(
    ffprobe \
        -v error \
        -select_streams a \
        -show_entries stream=bit_rate \
        -of default=noprint_wrappers=1:nokey=1 \
        "$1" \
    | awk '{sum+=$1} END {print sum}'
)"

if [ -z "$2" ]; then
    seek=""
    duration="$(
        ffprobe \
            -v error \
            -show_entries format=duration \
            -of default=noprint_wrappers=1:nokey=1 \
            "$1"
    )"
else
    seek="-sseof -$2"
    duration="$(
        echo "$2" \
        | sed -r 's/(.*):(.+):(.+)/\1*3600+\2*60+\3/;s/(.+):(.+)/\1*60+\2/' \
        | bc -l
    )"
fi

# Ceiling division, 2% overhead
video_bitrate="$(
    echo "((${MAX_SIZE} + ${duration} - 1) / ${duration} - ${audio_bitrate}) * 0.98" \
    | bc
)"

bufsize="$(echo "${video_bitrate} / 2" | bc)"

# Two-pass H.264 @ 720p30
ffmpeg \
    -hide_banner -loglevel 32 -y \
    $seek \
    -i "$1" \
    -c:v libx264 \
        -x264-params nal-hrd=cbr \
        -b:v "${video_bitrate}" \
        -minrate "${video_bitrate}" \
        -maxrate "${video_bitrate}" \
        -bufsize "${bufsize}" \
        -r 30 \
        -vf scale=-1:720 \
        -pass 1 \
        -passlogfile "${file_name}_2pass" \
    -an \
    -f mp4 /dev/null \
&& ffmpeg \
    -hide_banner -loglevel 32 \
    $seek \
    -i "$1" \
    -c:v libx264 \
        -x264-params nal-hrd=cbr \
        -b:v "${video_bitrate}" \
        -minrate "${video_bitrate}" \
        -maxrate "${video_bitrate}" \
        -bufsize "${bufsize}" \
        -r 30 \
        -vf scale=-1:720 \
        -pass 2 \
        -passlogfile "${file_name}_2pass" \
    -c:a copy \
    -map 0:v -map 0:a \
    "${file_name}_8mb.mp4"

# Clean up pass log files.
find . -name "${file_name}_2pass*.log*" -type f -delete