Automatically convert a video file into an 8MB file with decent quality to send via Discord.

DiscordSized.bat

@ECHO OFF

IF "%~1"=="" (
    ECHO No file provided, please drag and drop an MP4 onto this file to run.
    EXIT /B
)
IF %~z1 LSS 8388608 (
    ECHO File less than 8MB. Exiting.
    PAUSE
    exit
)

where /q ffprobe
IF ERRORLEVEL 1 (
    ECHO FFprobe is missing. Ensure it is installed and placed in your PATH. You can download the latest from here - https://www.ffmpeg.org/download.html
    PAUSE
    EXIT /B
)
where /q ffmpeg
IF ERRORLEVEL 1 (
    ECHO FFmpeg is missing. Ensure it is installed and placed in your PATH. You can download the latest from here - https://www.ffmpeg.org/download.html
    PAUSE
    EXIT /B
)

ECHO Shrinking %1 to be 8MB

ffprobe -loglevel error -select_streams a -show_entries stream=duration -of default=noprint_wrappers=1:nokey=1 %1 > durationFile
SET /P duration= < durationFile

:: Batch can't do floats, so round up (it will round down by default)
SET /A finalDuration = duration + 1
DEL durationFile

ECHO Duration rounded up to %finalDuration%

:: Bits to Bytes
SET /A totalBitrate = 8388608 / %finalDuration% * 8

ECHO Final bitrate is going to be %totalBitrate%

:: Subtract audio bitrate
SET /A videoBitrate = totalBitrate - 80000
SET /A audioBitrate = 80000

IF %videoBitrate% LSS 1500000 (
    ECHO Using veryslow preset due to long very duration video
    SET /A preset = "veryslow"
) ELSE (
    IF %videoBitrate% LSS 2000000 (
        ECHO Using slow preset due to long duration video
        SET /A preset = "slow"
    ) ELSE (
        ECHO Using default preset due to short video
        SET /A preset = "default"
    )
)

ffmpeg -y -i %1 -c:v libx264 -b:v %videoBitrate% -pass 1 -an -preset %preset% -f mp4 NUL && ^
ffmpeg -i %1 -c:v libx264 -b:v %videoBitrate% -pass 2 -c:a aac -b:a %audioBitrate% -preset %preset% Sized.mp4

del ffmpeg2pass-0.log
del ffmpeg2pass-0.log.mbtree