Convert video to 25M for wechat

To_25M.sh

#!/usr/bin/env bash

command -v mediainfo >/dev/null 2>&1 || { echo >&2 "mediainfo 命令不存在，请先安装 mediainfo。"; exit 1; }
command -v ffmpeg >/dev/null 2>&1 || { echo >&2 "ffmpeg 命令不存在，请先安装 ffmpeg。"; exit 1; }

out_size=24
length=$(mediainfo --Inform="Video;%Duration%" "$1")
bitrate_all=$(echo "${out_size}*8192/(${length}/1000)" | bc)

bitrate_audio_orig=$(mediainfo --Inform="Audio;%BitRate%" "$1")
if [ -z ${bitrate_audio_orig} ]; then
    bitrate_audio_orig=$(mediainfo --Inform="Audio;%BitRate_Nominal%" "$1")
fi

if [ ${bitrate_audio_orig} -gt 150000 ]; then
    convert_audio=true
    bitrate_audio=128
else
    bitrate_audio=$(echo "${bitrate_audio_orig}/1000" | bc)
fi

if [ ${bitrate_all} -lt 250 ]; then
    convert_audio=true
    bitrate_audio=48
fi

bitrate_video=$(echo "${bitrate_all}-${bitrate_audio}" | bc)

in_file="$1"
out_file=$(echo ${in_file} | sed -e 's/.mp4/_25M.mp4/')

ffmpeg -y -i ${in_file} -c:v libx265 -b:v ${bitrate_video}k -x265-params pass=1 -an -f mp4 /dev/null
if [ ${convert_audio} = true ]; then
    ffmpeg -i "$1" -c:v libx265 -b:v ${bitrate_video}k -x265-params pass=2 -c:a aac -b:a ${bitrate_audio}k ${out_file}
else
    ffmpeg -i "$1" -c:v libx265 -b:v ${bitrate_video}k -x265-params pass=2 -c:a copy ${out_file}
fi