add twitter-convert

packages/overlay.nix

@@ -2,6 +2,7 @@
 
 self: super: {
   fuckport = self.callPackage ./fuckport.nix { };
+  twitter-convert = self.callPackage ./twitter-convert { };
   nixci = flake.inputs.nixci.packages.${system}.default;
   nix-health = flake.inputs.nix-browser.packages.${system}.nix-health;
   actual = flake.inputs.actual.packages.${system}.default;

packages/twitter-convert/default.nix

@@ -0,0 +1,18 @@
+{ writeShellApplication, ffmpeg-full, ... }:
+
+# Some useful resources for this undocumented shit:
+# - https://stackoverflow.com/q/59056863/55246
+# - https://gist.github.com/nikhan/26ddd9c4e99bbf209dd7
+writeShellApplication {
+  name = "twitter-convert";
+  runtimeInputs = [ ffmpeg-full ];
+  meta.description = ''
+    Convert a video for uploading to X / Twitter.
+
+    You may need a Basic or Premium tier to upload longer videos.
+  '';
+  text = ''
+    export ARSCRIPT="${./ffmpeg_ar}"
+    ${./ffmpeg_twitter} "$1"
+  '';
+}

packages/twitter-convert/ffmpeg_ar

@@ -0,0 +1,12 @@
+#!/bin/bash
+eval $(ffprobe -v error -show_entries stream=width,height -of default=noprint_wrappers=1 "$1")
+#results in e.g.
+#width=300
+#height=1200
+echo "height=$height"$'\n'"width=$width"
+newenv=$(bc <<< "width=$width; height=$height;"$'\nscale=3; aspect=width / height;\nprint "aspect=", aspect;
+    print "''\n'$'";\n\nif (aspect>3) { r=(height) * (aspect/3); print "height=";}
+    if (aspect<(1/3)) {r=(width) / (aspect/(1/3)); print "width=";}\nscale=0
+    if (r) { print r/1 }')
+[ ! -z "$newenv" ] && echo "$newenv" && export $newenv
+echo "aspect=""$(bc <<< "scale=3; $width/$height")"

packages/twitter-convert/ffmpeg_twitter

@@ -0,0 +1,8 @@
+#!/usr/bin/env bash
+
+set -xe
+
+export $($ARSCRIPT "$1")
+ffmpeg -i "$1" \
+      -filter_complex 'fps=30,format=yuv420p,pad='"ceil($width/2)*2:ceil($height/2)*2"':(ow-iw)/2:(oh-ih)/2' -c:v h264_videotoolbox -c:a aac -ac 2 -ar 44100 -r 30 \
+      output.mp4