FFMPEG wrapper that compresses videos under target size

clipit.ps1

param (
    [Parameter(Mandatory)][string]$video,
    [float]$size = 10.0,
    [string]$name = "$($size)MB $([System.IO.Path]::GetFileNameWithoutExtension($video))",
    [ValidateSet("av1", "h264", "h265", "vp9")]
    [string]$encoder = "h264",
    [ValidateSet("amd", "nvidia", "intel", "none")]
    [string]$gpu = "amd",
    [ValidatePattern("\d+:\d+:\d+")]
    [string]$start = "00:00:00",
    [ValidatePattern("\d+:\d+:\d+")]
    [string]$end = "00:00:00",
    [ValidatePattern("\d+:\d+")]
    [string]$aspect_ratio = "$(ffprobe -v quiet -show_entries stream=display_aspect_ratio -of default=noprint_wrappers=1:nokey=1 $video)",
    [switch]$delete_original,
    [switch]$preserve_logs,
    [float]$volume = 1.0,
    [Alias("resolution")]
    [int]$height = 900,
    [int]$audio_bitrate = 128
)

if ($aspect_ratio -eq "N/A") {
    $w = "$(ffprobe -v error -select_streams v:0 -show_entries stream=width -of default=noprint_wrappers=1:nokey=1 $video)"
    $h = "$(ffprobe -v error -select_streams v:0 -show_entries stream=height -of default=noprint_wrappers=1:nokey=1 $video)"

    if ($w -gt $h) {
        $a = $w
        $b = $h
    }
    else {
        $a = $h
        $b = $w
    }

    while ($b -ne 0) {
        $r = $a % $b
        $a = $b
        $b = $r
    }
    $aspect_ratio = "$([int]($w/$a)):$([int]($h/$a))"
}

if ((Get-Item $video).length / 1MB -lt $size) {
    Rename-Item $video -NewName "$($name)$([System.IO.Path]::GetExtension($video))"
    exit
}

$width = [math]::Round(($height / $aspect_ratio.Split(":")[1]) * $aspect_ratio.Split(":")[0])
if ($width % 2 -eq 1) { $width -= 1 }

$start_seconds = [TimeSpan]::Parse($start).TotalSeconds
$end_seconds = [TimeSpan]::Parse($end).TotalSeconds
$duration = ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 $video
if ($end_seconds -eq "0") { $end_seconds = $duration }
else { $duration -= $duration - $end_seconds }

$duration -= $start_seconds
$video_bitrate = ($size * 8KB) / $duration - $audio_bitrate
if ($video_bitrate -lt 0) {
    Write-Host "With the current audio bitrate the video bitrate is negative. Please lower the audio bitrate with '-audio_bitrate'!"
    exit
}

$video_codec = ""
$audio_codec = "aac"
$video_extension = "mp4"
$repeat_count = 0.01

switch ($encoder) {
    "av1" {
        switch ($gpu) {
            "nvidia" { $video_codec = "av1_nvenc" }
            "intel" { $video_codec = "av1_qsv" }
            "amd" { $video_codec = "av1_amf" }
            default { $video_codec = "libaom-av1" }
        }
        $video_extension = "mkv"
    }
    "vp9" {
        switch ($gpu) {
            "intel" { $video_codec = "vp9_qsv" }
            default { $video_codec = "libvpx-vp9" }
        }
        $audio_codec = "libopus"
        $video_extension = "webm"
    }
    "h264" {
        switch ($gpu) {
            "amd" { $video_codec = "h264_amf" }
            "nvidia" { $video_codec = "h264_nvenc" }
            "intel" { $video_codec = "h264_qsv" }
            default { $video_codec = "libx264" }
        }
    }
    "h265" {
        switch ($gpu) {
            "amd" { $video_codec = "hevc_amf" }
            "nvidia" { $video_codec = "hevc_nvenc" }
            "intel" { $video_codec = " hevc_qsv" }
            default { $video_codec = "libx265" }
        }
    }
}

do {
    ffmpeg `
        -y `
        -i $video `
        -c:v $video_codec `
        -ss $start_seconds `
        -to $end_seconds `
        -vf "scale=-2:$($height), crop=$($width):$($height)" `
        -b:v "$($video_bitrate)k" `
        -pass 1 `
        -fps_mode vfr `
        -f null NUL

    ffmpeg `
        -y `
        -i $video `
        -c:v $video_codec `
        -ss $start_seconds `
        -to $end_seconds `
        -vf "scale=-2:$($height), crop=$($width):$($height)" `
        -b:v "$($video_bitrate)k" `
        -pass 2 `
        -c:a $audio_codec `
        -b:a "$($audio_bitrate)k" `
        -filter:a "volume=$volume" `
        -max_muxing_queue_size 9999 `
        "$($name).$($video_extension)"
    
    $actual_size = (Get-Item "$($name).$($video_extension)").length / 1MB
    $video_bitrate = ($video_bitrate * $size) / $actual_size 
    $video_bitrate = $video_bitrate * (1 - $repeat_count) # kept this just in case
    $repeat_count += 0.03
} while ($actual_size -gt $size)
    
if ($delete_original) {
    Remove-Item $video
}

if (!$preserve_logs) {
    Remove-Item "ffmpeg2pass-0.log" -ErrorAction SilentlyContinue
    Remove-Item "ffmpeg2pass-0.log.mbtree" -ErrorAction SilentlyContinue
}

Write-Output "Video took $(($repeat_count - 0.01) / 0.03) re-encodings until it went under $size MB."

• removed the validade range because it breaks it for some reason and I honestly can't be bothered to figure out why but otherwise the script still works
• changed the default size from 25mb to 10 since... discord lowered the upload limit to 10 :(

• added support for amd's av1 video encoder
• the bitrate decreases in bigger steps the more it has to re-encode the video because it would be over the size limit

• made the target bitrate change based on an rule of three approximation with the resulting size of the first encode result

• for some reason ffprobe can give back N/A as the aspect ratio. weird. added a shitty workaround for that just in case by computing the aspect ratio manually