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package thumbnail
import (
"context"
"fmt"
"os/exec"
"path/filepath"
"strconv"
"strings"
"time"
)
type Generator struct {
ffmpegPath string
}
func NewGenerator() *Generator {
return &Generator{
ffmpegPath: "ffmpeg",
}
}
func (g *Generator) Generate(ctx context.Context, videoPath string) (string, error) {
duration, err := g.probeVideoDuration(ctx, videoPath)
if err != nil {
return "", fmt.Errorf("probe video duration: %w", err)
}
timestamp := duration * time.Duration(thumbnailPercent) / 100
thumbnailPath := g.getThumbnailPath(videoPath)
if err := g.extractFrame(ctx, videoPath, thumbnailPath, timestamp); err != nil {
return "", fmt.Errorf("extract frame: %w", err)
}
return thumbnailPath, nil
}
func (g *Generator) probeVideoDuration(ctx context.Context, videoPath string) (time.Duration, error) {
args := []string{
"-v", "error",
"-show_entries", "format=duration",
"-of", "default=noprint_wrappers=1:nokey=1",
videoPath,
}
ctx, cancel := context.WithTimeout(ctx, 15*time.Second)
defer cancel()
cmd := exec.CommandContext(ctx, "ffprobe", args...)
output, err := cmd.Output()
if err != nil {
return 0, err
}
seconds, err := strconv.ParseFloat(strings.TrimSpace(string(output)), 64)
if err != nil {
return 0, err
}
return time.Duration(seconds * float64(time.Second)), nil
}
func (g *Generator) extractFrame(ctx context.Context, videoPath, thumbnailPath string, timestamp time.Duration) error {
thumbnailDir := filepath.Dir(thumbnailPath)
if err := ensureDir(thumbnailDir); err != nil {
return err
}
timestampSec := timestamp.Seconds()
timestampStr := fmt.Sprintf("%.3f", timestampSec)
args := []string{
"-ss", timestampStr,
"-i", videoPath,
"-vframes", "1",
"-vf", fmt.Sprintf("scale=%d:%d", thumbnailWidth, thumbnailHeight),
"-y",
thumbnailPath,
}
ctx, cancel := context.WithTimeout(ctx, 30*time.Second)
defer cancel()
cmd := exec.CommandContext(ctx, g.ffmpegPath, args...)
if err := cmd.Run(); err != nil {
return err
}
return nil
}
func (g *Generator) getThumbnailPath(videoPath string) string {
dir := filepath.Dir(videoPath)
thumbnailDir := filepath.Join(dir, thumbnailDir)
filename := filepath.Base(videoPath)
ext := filepath.Ext(filename)
name := strings.TrimSuffix(filename, ext)
return filepath.Join(thumbnailDir, name+"."+thumbnailFormat)
}
func ensureDir(path string) error {
if _, err := exec.LookPath("mkdir"); err == nil {
cmd := exec.Command("mkdir", "-p", path)
return cmd.Run()
}
return fmt.Errorf("mkdir not found")
}
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