132 lines
3.3 KiB
Go
132 lines
3.3 KiB
Go
package files
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import (
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"context"
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"fmt"
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"os"
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"os/exec"
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"strings"
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"time"
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)
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const (
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videoThumbnailTimeout = 5 * time.Second
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videoThumbnailMaxInputBytes = 200 << 20 // 200MB；更大文件本阶段跳过 fallback，避免阻塞发送。
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videoThumbnailMaxConcurrent = 2
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)
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// VideoThumbnailer 从视频字节中抽取静态缩略图。实现必须可失败降级，不影响原发送流程。
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type VideoThumbnailer interface {
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Extract(ctx context.Context, data []byte, mimeType string) ([]byte, error)
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}
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// FFmpegVideoThumbnailer 使用本机 ffmpeg 抽取第一帧 JPEG。
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type FFmpegVideoThumbnailer struct {
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path string
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timeout time.Duration
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slots chan struct{}
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}
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// NewFFmpegVideoThumbnailer 返回基于 PATH 中 ffmpeg 的抽帧器。
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func NewFFmpegVideoThumbnailer() (*FFmpegVideoThumbnailer, error) {
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path, err := exec.LookPath("ffmpeg")
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if err != nil {
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return nil, err
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}
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return &FFmpegVideoThumbnailer{
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path: path,
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timeout: videoThumbnailTimeout,
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slots: make(chan struct{}, videoThumbnailMaxConcurrent),
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}, nil
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}
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// Extract 抽取第一帧并输出 JPEG bytes。
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func (t *FFmpegVideoThumbnailer) Extract(ctx context.Context, data []byte, mimeType string) ([]byte, error) {
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if t == nil || t.path == "" {
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return nil, fmt.Errorf("ffmpeg thumbnailer unavailable")
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}
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if len(data) == 0 {
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return nil, fmt.Errorf("empty video data")
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}
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if len(data) > videoThumbnailMaxInputBytes {
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return nil, fmt.Errorf("video too large for thumbnail fallback: %d bytes", len(data))
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}
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select {
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case t.slots <- struct{}{}:
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defer func() { <-t.slots }()
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case <-ctx.Done():
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return nil, ctx.Err()
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}
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runCtx, cancel := context.WithTimeout(ctx, t.timeout)
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defer cancel()
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input, err := os.CreateTemp("", "telesrv-video-*"+videoTempExt(mimeType))
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if err != nil {
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return nil, fmt.Errorf("create temp video: %w", err)
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}
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inputPath := input.Name()
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defer os.Remove(inputPath)
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if _, err := input.Write(data); err != nil {
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input.Close()
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return nil, fmt.Errorf("write temp video: %w", err)
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}
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if err := input.Close(); err != nil {
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return nil, fmt.Errorf("close temp video: %w", err)
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}
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output, err := os.CreateTemp("", "telesrv-video-thumb-*.jpg")
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if err != nil {
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return nil, fmt.Errorf("create temp thumbnail: %w", err)
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}
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outputPath := output.Name()
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output.Close()
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defer os.Remove(outputPath)
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cmd := exec.CommandContext(
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runCtx,
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t.path,
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"-hide_banner",
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"-loglevel", "error",
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"-y",
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"-i", inputPath,
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"-map", "0:v:0",
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"-frames:v", "1",
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"-an",
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"-vf", "scale=320:320:force_original_aspect_ratio=decrease",
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"-q:v", "3",
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outputPath,
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)
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stderr, err := cmd.CombinedOutput()
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if runCtx.Err() != nil {
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return nil, runCtx.Err()
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}
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if err != nil {
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msg := strings.TrimSpace(string(stderr))
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if msg != "" {
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return nil, fmt.Errorf("ffmpeg extract thumbnail: %w: %s", err, msg)
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}
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return nil, fmt.Errorf("ffmpeg extract thumbnail: %w", err)
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}
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thumb, err := os.ReadFile(outputPath)
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if err != nil {
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return nil, fmt.Errorf("read thumbnail: %w", err)
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}
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if len(thumb) == 0 {
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return nil, fmt.Errorf("ffmpeg produced empty thumbnail")
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}
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return thumb, nil
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}
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func videoTempExt(mimeType string) string {
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switch strings.ToLower(strings.TrimSpace(mimeType)) {
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case "video/mp4":
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return ".mp4"
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case "video/quicktime":
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return ".mov"
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case "video/webm":
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return ".webm"
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default:
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return ".bin"
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}
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}
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