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/reader.go

@@ -0,0 +1,140 @@
+package rtp
+
+import (
+	"errors"
+	"fmt"
+	"io"
+
+	"github.com/pion/rtp"
+	"m7s.live/v5/pkg/util"
+)
+
+type IRTPReader interface {
+	Read(packet *rtp.Packet) (err error)
+}
+
+type RTPUDPReader struct {
+	io.Reader
+	buf [MTUSize]byte
+}
+
+func NewRTPUDPReader(r io.Reader) *RTPUDPReader {
+	return &RTPUDPReader{Reader: r}
+}
+
+func (r *RTPUDPReader) Read(packet *rtp.Packet) (err error) {
+	n, err := r.Reader.Read(r.buf[:])
+	if err != nil {
+		return err
+	}
+	return packet.Unmarshal(r.buf[:n])
+}
+
+type RTPTCPReader struct {
+	*util.BufReader
+	buffer util.Buffer
+}
+
+func NewRTPTCPReader(r io.Reader) *RTPTCPReader {
+	return &RTPTCPReader{BufReader: util.NewBufReader(r)}
+}
+
+func (r *RTPTCPReader) Read(packet *rtp.Packet) (err error) {
+	var rtplen uint32
+	var b0, b1 byte
+	rtplen, err = r.ReadBE32(2)
+	if err != nil {
+		return
+	}
+	var mem util.Memory
+	mem, err = r.ReadBytes(int(rtplen))
+	if err != nil {
+		return
+	}
+	mr := mem.NewReader()
+	mr.ReadByteTo(&b0, &b1)
+	if b0>>6 != 2 || b0&0x0f > 15 || b1&0x7f > 127 {
+		// TODO:
+		panic(fmt.Errorf("invalid rtp packet: %x", r.buffer[:2]))
+	} else {
+		r.buffer.Relloc(int(rtplen))
+		mem.CopyTo(r.buffer)
+		err = packet.Unmarshal(r.buffer)
+	}
+	return
+}
+
+type RTPPayloadReader struct {
+	IRTPReader
+	rtp.Packet
+	SSRC   uint32 // RTP SSRC
+	buffer util.MemoryReader
+}
+
+// func NewTCPRTPPayloadReaderForFeed() *RTPPayloadReader {
+// 	r := &RTPPayloadReader{}
+// 	r.IRTPReader = &RTPTCPReader{
+// 		BufReader: util.NewBufReaderChan(10),
+// 	}
+// 	r.buffer.Memory = &util.Memory{}
+// 	return r
+// }
+
+func NewRTPPayloadReader(t IRTPReader) *RTPPayloadReader {
+	r := &RTPPayloadReader{}
+	r.IRTPReader = t
+	r.buffer.Memory = &util.Memory{}
+	return r
+}
+
+func (r *RTPPayloadReader) Read(buf []byte) (n int, err error) {
+	// 如果缓冲区中有数据，先读取缓冲区中的数据
+	if r.buffer.Length > 0 {
+		n, _ = r.buffer.Read(buf)
+		return n, nil
+	}
+
+	// 读取新的RTP包
+	for {
+		lastSeq := r.SequenceNumber
+		err = r.IRTPReader.Read(&r.Packet)
+		if err != nil {
+			err = errors.Join(err, fmt.Errorf("failed to read RTP packet"))
+			return
+		}
+
+		// 检查SSRC是否匹配
+		if r.SSRC != 0 && r.SSRC != r.Packet.SSRC {
+			// SSRC不匹配，继续读取下一个包
+			continue
+		}
+
+		// 检查序列号是否连续
+		if lastSeq == 0 || r.SequenceNumber == lastSeq+1 {
+			// 序列号连续，处理当前包的数据
+			if lbuf, lpayload := len(buf), len(r.Payload); lbuf >= lpayload {
+				// 缓冲区足够大，可以容纳整个负载
+				copy(buf, r.Payload)
+				n += lpayload
+
+				// 如果缓冲区还有剩余空间，继续读取下一个包
+				if lbuf > lpayload {
+					var nextn int
+					nextn, err = r.Read(buf[lpayload:])
+					if err != nil && err != io.EOF {
+						return n, err
+					}
+					n += nextn
+				}
+				return
+			} else {
+				// 缓冲区不够大，只复制部分数据，将剩余数据放入缓冲区
+				n += lbuf
+				copy(buf, r.Payload[:lbuf])
+				r.buffer.PushOne(r.Payload[lbuf:])
+				r.buffer.Length = lpayload - lbuf
+				return
+			}
+		}
+	}
+}