Implement Tuner v1 — Go backend, React frontend, Docker setup

- Go backend: REST API, M3U parser, FFmpeg/MediaMTX process manager
- React/Vite frontend: HLS player, admin panel, channel browser (dark theme)
- MediaMTX config for RTMP ingest + HLS output
- Multi-stage Dockerfile (Go + Bun + Alpine runtime)
- docker-compose.yml for single-container deployment
- Sample M3U playlist with test streams

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/process/ffmpeg.go

@@ -0,0 +1,115 @@
+package process
+
+import (
+	"fmt"
+	"log"
+	"os/exec"
+	"sync"
+	"time"
+
+	"tuner/models"
+)
+
+// FFmpegManager manages an FFmpeg child process for IPTV relay.
+type FFmpegManager struct {
+	mu        sync.Mutex
+	cmd       *exec.Cmd
+	startTime time.Time
+	lastError string
+	streamURL string
+}
+
+// NewFFmpegManager creates a new FFmpeg process manager.
+func NewFFmpegManager() *FFmpegManager {
+	return &FFmpegManager{}
+}
+
+// Start spawns an FFmpeg process to pull from streamURL and push RTMP to MediaMTX.
+// It kills any existing FFmpeg process first.
+func (f *FFmpegManager) Start(streamURL string) error {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+
+	// Kill existing process if running
+	f.stopLocked()
+
+	f.cmd = exec.Command("ffmpeg",
+		"-re",
+		"-i", streamURL,
+		"-c", "copy",
+		"-f", "flv",
+		"rtmp://localhost:1935/live/stream",
+	)
+	f.streamURL = streamURL
+	f.lastError = ""
+
+	if err := f.cmd.Start(); err != nil {
+		f.lastError = err.Error()
+		return fmt.Errorf("start ffmpeg: %w", err)
+	}
+
+	f.startTime = time.Now()
+	log.Printf("[ffmpeg] started with pid %d, source: %s", f.cmd.Process.Pid, streamURL)
+
+	// Monitor in background
+	go f.monitor()
+
+	return nil
+}
+
+func (f *FFmpegManager) monitor() {
+	err := f.cmd.Wait()
+
+	f.mu.Lock()
+	defer f.mu.Unlock()
+
+	if err != nil {
+		f.lastError = err.Error()
+		log.Printf("[ffmpeg] exited: %v", err)
+	} else {
+		log.Println("[ffmpeg] exited (status 0)")
+	}
+
+	f.cmd = nil
+}
+
+// Stop kills the FFmpeg process.
+func (f *FFmpegManager) Stop() error {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	return f.stopLocked()
+}
+
+func (f *FFmpegManager) stopLocked() error {
+	if f.cmd == nil || f.cmd.Process == nil {
+		return nil
+	}
+
+	if err := f.cmd.Process.Kill(); err != nil {
+		return fmt.Errorf("kill ffmpeg: %w", err)
+	}
+
+	// Wait for the process to fully exit to avoid zombies
+	_ = f.cmd.Wait()
+	f.cmd = nil
+	log.Println("[ffmpeg] killed")
+	return nil
+}
+
+// Status returns the current FFmpeg process status.
+func (f *FFmpegManager) Status() models.ProcessInfo {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+
+	info := models.ProcessInfo{
+		Error: f.lastError,
+	}
+
+	if f.cmd != nil && f.cmd.Process != nil {
+		info.Running = true
+		info.PID = f.cmd.Process.Pid
+		info.Uptime = time.Since(f.startTime).Truncate(time.Second).String()
+	}
+
+	return info
+}