Added basic video preview script

modules/video_previews.sh

@@ -0,0 +1,72 @@
+#!/bin/bash
+
+preview_dir="$(dirname "$0")/../previews"
+
+search_dir="${1}"
+
+check_dependencies() {
+	if ! mkdir -p "$preview_dir"; then
+		echo "ERROR: Unable to create preview directory"
+		exit 1
+	elif ! command -v ffmpeg 2>&1 >/dev/null; then
+		echo "ERROR: FFmpeg must be installed"
+		exit 1
+	fi
+}
+
+check_input() {
+	if [[ ! -e "${search_dir}" ]]; then
+		echo "ERROR: Input file '${search_dir}' does not exist"
+		exit 2
+	fi
+}
+
+# Search for videos recursively using the MIME type
+find_videos() {
+	video_list=$(find "${search_dir}" -type f -exec file -i {} \; | grep -oP '.*(?=: video/)')
+
+	echo "${video_list}" >&2
+}
+
+create_previews() {
+	while IFS= read -r video; do
+		echo "Making preview for ${video}"
+		make_preview
+	done <<< "${video_list}"
+}
+
+get_size() {
+	IFS=','
+	read -r width height <<< $(ffprobe -v error -select_streams v -show_entries stream=width,height -of csv=p=0 "${video}")
+
+	if [[ $width -gt $height ]]; then
+		rows=4 cols=5
+		scale_format="200:-1"
+	else
+		rows=5 cols=4
+		scale_format="-1:200"
+	fi
+}
+
+get_num_frames() {
+	local num_snapshots=$(( rows * cols ))
+
+	num_frames=$(ffprobe -v error -select_streams v:0 -count_frames -show_entries stream=nb_read_frames -of csv=p=0 "${video}")
+	echo "Num frames: $num_frames" >&2
+
+	frames_per_snapshot=$(( num_frames / num_snapshots ))
+}
+
+make_preview() {
+	get_size
+	get_num_frames
+
+	filename="$(basename "${video}")"
+
+    ffmpeg -nostdin -loglevel panic -i "${video}" -frames 1 -q:v 90 -vf "select=not(mod(n\,$frames_per_snapshot)),scale=$scale_format,tile=${rows}x${cols}" "$preview_dir/${filename}.webp"
+}
+
+check_dependencies
+check_input
+find_videos
+create_previews