1// Package ffmpeg provides FFmpeg integration for timelapse generation.
 2package ffmpeg
 3
 4import (
 5	"fmt"
 6	"os"
 7	"path/filepath"
 8	"strings"
 9)
10
11// GenerateConcatFile creates an FFmpeg concat demuxer file.
12// Each path in the list is written as "file '<path>'" on its own line.
13// Paths are converted to absolute paths since ffmpeg's concat demuxer
14// resolves relative paths relative to the concat file's directory.
15func GenerateConcatFile(outputPath string, clipPaths []string) error {
16	var b strings.Builder
17
18	for _, path := range clipPaths {
19		// Convert to absolute path for ffmpeg concat demuxer
20		absPath, err := filepath.Abs(path)
21		if err != nil {
22			return fmt.Errorf("getting absolute path for %s: %w", path, err)
23		}
24		// Escape single quotes in path by replacing ' with '\''
25		escaped := strings.ReplaceAll(absPath, "'", "'\\''")
26		fmt.Fprintf(&b, "file '%s'\n", escaped)
27	}
28
29	err := os.WriteFile(outputPath, []byte(b.String()), 0644)
30	if err != nil {
31		return fmt.Errorf("writing concat file: %w", err)
32	}
33
34	return nil
35}