update script

scripts/mkv-to-readme-video.sh

@@ -3,23 +3,56 @@
 set -euo pipefail
 
 usage() {
-  cat <<'EOF'
+	cat << 'USAGE'
 Usage:
-  scripts/mkv-to-readme-video.sh <input.mkv>
+  scripts/mkv-to-readme-video.sh [--force] <input.mkv>
 
 Description:
   Generates two browser-friendly files next to the input file:
   - <name>.mp4  (H.264 + AAC, prefers NVIDIA GPU if available)
   - <name>.webm (AV1/VP9 + Opus, prefers NVIDIA GPU if available)
-EOF
+  - <name>.gif  (palette-optimised, 15 fps)
+
+Options:
+  -f, --force  Overwrite existing output files
+
+Encoding profile:
+  - Crop: 1920x1080 at x=760 y=180
+  - MP4:  H.264 + AAC
+  - WebM: AV1/VP9 + Opus at 30 fps
+USAGE
 }
 
-if [[ "${1:-}" == "-h" || "${1:-}" == "--help" ]]; then
+force=0
+input=""
+
+while [[ $# -gt 0 ]]; do
+	case "$1" in
+		-h|--help)
 			usage
 			exit 0
+			;;
+		-f|--force)
+			force=1
+			;;
+		-*)
+			echo "Error: unknown option: $1" >&2
+			usage
+			exit 1
+			;;
+		*)
+			if [[ -n "$input" ]]; then
+				echo "Error: expected exactly one input file." >&2
+				usage
+				exit 1
 			fi
+			input="$1"
+			;;
+	esac
+	shift
+done
 
-if [[ $# -ne 1 ]]; then
+if [[ -z "$input" ]]; then
 	usage
 	exit 1
 fi
@@ -29,8 +62,6 @@ if ! command -v ffmpeg >/dev/null 2>&1; then
 	exit 1
 fi
 
-input="$1"
-
 if [[ ! -f "$input" ]]; then
 	echo "Error: input file not found: $input" >&2
 	exit 1
@@ -42,24 +73,55 @@ base="${filename%.*}"
 
 mp4_out="$dir/$base.mp4"
 webm_out="$dir/$base.webm"
+gif_out="$dir/$base.gif"
+
+overwrite_flag="-n"
+if [[ "$force" -eq 1 ]]; then
+	overwrite_flag="-y"
+fi
+
+if [[ "$force" -eq 0 ]]; then
+	for output in "$mp4_out" "$webm_out" "$gif_out"; do
+		if [[ -e "$output" ]]; then
+			echo "Error: output exists: $output (use --force to overwrite)" >&2
+			exit 1
+		fi
+	done
+fi
 
 has_encoder() {
 	local encoder="$1"
 	ffmpeg -hide_banner -encoders 2> /dev/null | grep -qE "[[:space:]]${encoder}[[:space:]]"
 }
 
+crop_vf="crop=1920:1080:760:180"
+webm_vf="${crop_vf},fps=30"
+gif_vf="${crop_vf},fps=15,scale=960:-1:flags=lanczos,split[s0][s1];[s0]palettegen=max_colors=128[p];[s1][p]paletteuse=dither=bayer:bayer_scale=3"
+
 echo "Generating MP4: $mp4_out"
 if has_encoder "h264_nvenc"; then
-  echo "Using GPU encoder for MP4: h264_nvenc"
-  ffmpeg -y -i "$input" \
-    -c:v h264_nvenc -preset p5 -cq 20 \
-    -profile:v high -pix_fmt yuv420p \
+	echo "Trying GPU encoder for MP4: h264_nvenc"
+	if ffmpeg "$overwrite_flag" -i "$input" \
+		-vf "$crop_vf" \
+		-c:v h264_nvenc -preset p6 -rc:v vbr -cq:v 20 -b:v 0 \
+		-pix_fmt yuv420p -movflags +faststart \
+		-c:a aac -b:a 160k \
+		"$mp4_out"; then
+		:
+	else
+		echo "GPU MP4 encode failed; retrying with CPU encoder: libx264"
+		ffmpeg "$overwrite_flag" -i "$input" \
+			-vf "$crop_vf" \
+			-c:v libx264 -preset slow -crf 20 \
+			-profile:v high -level 4.1 -pix_fmt yuv420p \
 			-movflags +faststart \
 			-c:a aac -b:a 160k \
 			"$mp4_out"
+	fi
 else
 	echo "Using CPU encoder for MP4: libx264"
-  ffmpeg -y -i "$input" \
+	ffmpeg "$overwrite_flag" -i "$input" \
+		-vf "$crop_vf" \
 		-c:v libx264 -preset slow -crf 20 \
 		-profile:v high -level 4.1 -pix_fmt yuv420p \
 		-movflags +faststart \
@@ -69,19 +131,38 @@ fi
 
 echo "Generating WebM: $webm_out"
 if has_encoder "av1_nvenc"; then
-  echo "Using GPU encoder for WebM: av1_nvenc"
-  ffmpeg -y -i "$input" \
-    -c:v av1_nvenc -preset p5 -cq 30 -b:v 0 \
-    -c:a libopus -b:a 128k \
-    "$webm_out"
+	echo "Trying GPU encoder for WebM: av1_nvenc"
+	if ffmpeg "$overwrite_flag" -i "$input" \
+		-vf "$webm_vf" \
+		-c:v av1_nvenc -preset p6 -cq:v 34 -b:v 0 \
+		-c:a libopus -b:a 96k \
+		"$webm_out"; then
+		:
 	else
-  echo "Using CPU encoder for WebM: libvpx-vp9"
-  ffmpeg -y -i "$input" \
-    -c:v libvpx-vp9 -crf 32 -b:v 0 \
-    -c:a libopus -b:a 128k \
+		echo "GPU WebM encode failed; retrying with CPU encoder: libvpx-vp9"
+		ffmpeg "$overwrite_flag" -i "$input" \
+			-vf "$webm_vf" \
+			-c:v libvpx-vp9 -crf 34 -b:v 0 \
+			-row-mt 1 -threads 8 \
+			-c:a libopus -b:a 96k \
 			"$webm_out"
 	fi
+else
+	echo "Using CPU encoder for WebM: libvpx-vp9"
+	ffmpeg "$overwrite_flag" -i "$input" \
+		-vf "$webm_vf" \
+		-c:v libvpx-vp9 -crf 34 -b:v 0 \
+		-row-mt 1 -threads 8 \
+		-c:a libopus -b:a 96k \
+		"$webm_out"
+fi
+
+echo "Generating GIF: $gif_out"
+ffmpeg "$overwrite_flag" -i "$input" \
+	-vf "$gif_vf" \
+	"$gif_out"
 
 echo "Done."
 echo "MP4:  $mp4_out"
 echo "WebM: $webm_out"
+echo "GIF:  $gif_out"