massive rewrite using flake-parts

Signed-off-by: Amneesh Singh <natto@weirdnatto.in>

pkgs/customscripts/src/compress

@@ -0,0 +1,33 @@
+#!/usr/bin/env nix-shell
+#! nix-shell -i bash -p ffmpeg
+
+target_video_size_KB="$2"
+origin_duration_s=$(ffprobe -v error -show_streams -select_streams a "$1" | grep -Po "(?<=^duration\=)\d*\.\d*")
+echo $origin_duration_s
+origin_audio_bitrate_kbit_s=$(ffprobe -v error -pretty -show_streams -select_streams a "$1" | grep -Po "(?<=^bit_rate\=)\d*\.\d*")
+target_audio_bitrate_kbit_s=$origin_audio_bitrate_kbit_s
+target_video_bitrate_kbit_s=$(\
+    awk \
+    -v size="$target_video_size_KB" \
+    -v duration="$origin_duration_s" \
+    -v audio_rate="$target_audio_bitrate_kbit_s" \
+    'BEGIN { print  ( ( size * 8.0 ) / ( 1.048576 * duration ) - audio_rate ) }')
+
+ffmpeg \
+    -y \
+    -i "$1" \
+    -c:v libx264 \
+    -b:v "$target_video_bitrate_kbit_s"k \
+    -pass 1 \
+    -an \
+    -f mp4 \
+    /dev/null \
+&& \
+ffmpeg \
+    -i "$1" \
+    -c:v libx264 \
+    -b:v "$target_video_bitrate_kbit_s"k \
+    -pass 2 \
+    -c:a aac \
+    -b:a "$target_audio_bitrate_kbit_s"k \
+    "$3"