chore: 初始化仓库基线（AGENTS.md、git 规范、敏感文件排除）

2026-08-10 22:30:53 +08:00
commit 84abf4454c
358 changed files with 75993 additions and 0 deletions
@@ -0,0 +1,172 @@
+package service
+
+import (
+	"bufio"
+	"context"
+	"fmt"
+	"io"
+	"log/slog"
+	"os/exec"
+
+	"silk-server-go/internal/model"
+
+	"gorm.io/gorm"
+)
+
+// TranscodeService ffmpeg 实时转码服务
+type TranscodeService struct {
+	db  *gorm.DB
+	s3  *S3Service
+	sem chan struct{} // 信号量，限制并发转码数为 4
+}
+
+// NewTranscodeService 创建转码服务，信号量默认容量 4
+func NewTranscodeService(db *gorm.DB, s3 *S3Service) *TranscodeService {
+	return &TranscodeService{
+		db:  db,
+		s3:  s3,
+		sem: make(chan struct{}, 4),
+	}
+}
+
+// StreamLive 通过 ffmpeg 实时转码直播流（H264 re-encode for browser compatibility）
+func (s *TranscodeService) StreamLive(sourceURL string, writer io.Writer) error {
+	s.sem <- struct{}{}
+	defer func() { <-s.sem }()
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	cmd := exec.CommandContext(ctx, "ffmpeg",
+		"-i", sourceURL,
+		"-c:v", "libx264",
+		"-preset", "ultrafast",
+		"-tune", "zerolatency",
+		"-b:v", "1M",
+		"-maxrate", "1.5M",
+		"-bufsize", "1M",
+		"-g", "30",
+		"-an",
+		"-f", "flv",
+		"pipe:1",
+	)
+
+	stdoutPipe, err := cmd.StdoutPipe()
+	if err != nil {
+		return fmt.Errorf("创建 stdout 管道失败: %w", err)
+	}
+	stderrPipe, err := cmd.StderrPipe()
+	if err != nil {
+		return fmt.Errorf("创建 stderr 管道失败: %w", err)
+	}
+
+	if err := cmd.Start(); err != nil {
+		return fmt.Errorf("启动 ffmpeg 失败: %w", err)
+	}
+
+	defer func() {
+		if cmd.ProcessState == nil || !cmd.ProcessState.Exited() {
+			_ = cmd.Process.Kill()
+		}
+	}()
+
+	go func() {
+		scanner := bufio.NewScanner(stderrPipe)
+		for scanner.Scan() {
+			slog.Info("ffmpeg-live", "msg", scanner.Text())
+		}
+	}()
+
+	if _, err := io.Copy(writer, stdoutPipe); err != nil {
+		cancel()
+		return fmt.Errorf("流式传输失败: %w", err)
+	}
+
+	if err := cmd.Wait(); err != nil {
+		if ctx.Err() != nil {
+			return ctx.Err()
+		}
+		return fmt.Errorf("ffmpeg 异常退出: %w", err)
+	}
+
+	return nil
+}
+
+// StreamClip 通过 ffmpeg 实时转码视频片段并流式写入 writer
+// 流程：查库获取 S3 信息 → 生成 presigned URL → ffmpeg -c copy 转封装为 fragmented MP4 → 管道输出
+func (s *TranscodeService) StreamClip(clipId string, writer io.Writer) error {
+	// 1. 查库获取 clip 的 s3Bucket + s3Key
+	var clip model.VideoClip
+	if err := s.db.Where("id = ?", clipId).First(&clip).Error; err != nil {
+		return fmt.Errorf("视频片段不存在: %w", err)
+	}
+	if clip.S3Bucket == nil || clip.S3Key == nil || *clip.S3Bucket == "" || *clip.S3Key == "" {
+		return fmt.Errorf("该片段没有 S3 对象")
+	}
+
+	// 2. 生成 S3 presigned URL
+	presignedURL, err := s.s3.GetPresignedURL(*clip.S3Bucket, *clip.S3Key)
+	if err != nil {
+		return fmt.Errorf("生成 presigned URL 失败: %w", err)
+	}
+
+	// 3. 获取信号量（并发限制 4）
+	s.sem <- struct{}{}
+	defer func() { <-s.sem }()
+
+	// 4. 启动 ffmpeg: ffmpeg -i <url> -c copy -movflags frag_keyframe+empty_moov -f mp4 pipe:1
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	cmd := exec.CommandContext(ctx, "ffmpeg",
+		"-i", presignedURL,
+		"-c", "copy",
+		"-movflags", "frag_keyframe+empty_moov",
+		"-f", "mp4",
+		"pipe:1",
+	)
+
+	stdoutPipe, err := cmd.StdoutPipe()
+	if err != nil {
+		return fmt.Errorf("创建 stdout 管道失败: %w", err)
+	}
+	stderrPipe, err := cmd.StderrPipe()
+	if err != nil {
+		return fmt.Errorf("创建 stderr 管道失败: %w", err)
+	}
+
+	if err := cmd.Start(); err != nil {
+		return fmt.Errorf("启动 ffmpeg 失败: %w", err)
+	}
+
+	// 确保 ffmpeg 进程被清理（如果还在运行则 kill）
+	defer func() {
+		if cmd.ProcessState == nil || !cmd.ProcessState.Exited() {
+			_ = cmd.Process.Kill()
+		}
+	}()
+
+	// 5. 记录 ffmpeg stderr 日志
+	go func() {
+		scanner := bufio.NewScanner(stderrPipe)
+		for scanner.Scan() {
+			slog.Info("ffmpeg", "clipId", clipId, "msg", scanner.Text())
+		}
+	}()
+
+	// 6. 流式传输：io.Copy(writer, ffmpeg.Stdout)
+	if _, err := io.Copy(writer, stdoutPipe); err != nil {
+		cancel() // 取消 context，终止 ffmpeg
+		return fmt.Errorf("流式传输失败: %w", err)
+	}
+
+	// 7. 等待 ffmpeg 结束，检查退出码
+	if err := cmd.Wait(); err != nil {
+		if ctx.Err() != nil {
+			return ctx.Err()
+		}
+		return fmt.Errorf("ffmpeg 异常退出: %w", err)
+	}
+
+	return nil
+}