refactor: frame converter and mp4 track improvements

- Refactor frame converter implementation
- Update mp4 track to use ICodex
- General refactoring and code improvements

🤖 Generated with [Claude Code](https://claude.ai/code)

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

plugin/rtp/pkg/puller-dump.go

@@ -0,0 +1,48 @@
+package rtp
+
+import (
+	"time"
+
+	m7s "m7s.live/v5"
+	"m7s.live/v5/pkg/util"
+)
+
+type DumpPuller struct {
+	m7s.HTTPFilePuller
+}
+
+func (p *DumpPuller) Start() (err error) {
+	p.PullJob.PublishConfig.PubType = m7s.PublishTypeReplay
+	return p.HTTPFilePuller.Start()
+}
+
+func (p *DumpPuller) Run() (err error) {
+	pub := p.PullJob.Publisher
+	var receiver PSReceiver
+	receiver.Publisher = pub
+	receiver.StreamMode = StreamModeManual
+	receiver.OnStart(func() {
+		go func() {
+			var t uint16
+			for l := make([]byte, 6); pub.State != m7s.PublisherStateDisposed; time.Sleep(time.Millisecond * time.Duration(t)) {
+				_, err = p.Read(l)
+				if err != nil {
+					return
+				}
+				payloadLen := util.ReadBE[int](l[:4])
+				payload := make([]byte, payloadLen)
+				t = util.ReadBE[uint16](l[4:])
+				_, err = p.Read(payload)
+				if err != nil {
+					return
+				}
+				select {
+				case receiver.RTPMouth <- payload:
+				case <-pub.Done():
+					return
+				}
+			}
+		}()
+	})
+	return p.RunTask(&receiver)
+}