move RTP decoders/encoders into pkt/rtpcodecs

pkg/rtpcodecs/rtpvp8/decoder.go

@@ -0,0 +1,75 @@
+package rtpvp8
+
+import (
+	"errors"
+	"fmt"
+	"time"
+
+	"github.com/pion/rtp"
+	"github.com/pion/rtp/codecs"
+
+	"github.com/aler9/gortsplib/pkg/rtptimedec"
+)
+
+// ErrMorePacketsNeeded is returned when more packets are needed.
+var ErrMorePacketsNeeded = errors.New("need more packets")
+
+// Decoder is a RTP/VP8 decoder.
+type Decoder struct {
+	timeDecoder *rtptimedec.Decoder
+	fragments   [][]byte
+}
+
+// Init initializes the decoder.
+func (d *Decoder) Init() {
+	d.timeDecoder = rtptimedec.New(rtpClockRate)
+}
+
+// Decode decodes a VP8 frame from a RTP/VP8 packet.
+func (d *Decoder) Decode(pkt *rtp.Packet) ([]byte, time.Duration, error) {
+	var vpkt codecs.VP8Packet
+	_, err := vpkt.Unmarshal(pkt.Payload)
+	if err != nil {
+		return nil, 0, err
+	}
+
+	if vpkt.PID != 0 {
+		return nil, 0, fmt.Errorf("packets containing single partitions are not supported")
+	}
+
+	if vpkt.S == 1 {
+		d.fragments = d.fragments[:0]
+
+		if pkt.Marker {
+			return vpkt.Payload, d.timeDecoder.Decode(pkt.Timestamp), nil
+		}
+
+		d.fragments = append(d.fragments, vpkt.Payload)
+		return nil, 0, ErrMorePacketsNeeded
+	}
+
+	if len(d.fragments) == 0 {
+		return nil, 0, fmt.Errorf("received a non-starting fragment")
+	}
+
+	d.fragments = append(d.fragments, vpkt.Payload)
+
+	if !pkt.Marker {
+		return nil, 0, ErrMorePacketsNeeded
+	}
+
+	n := 0
+	for _, frag := range d.fragments {
+		n += len(frag)
+	}
+
+	frame := make([]byte, n)
+	pos := 0
+
+	for _, frag := range d.fragments {
+		pos += copy(frame[pos:], frag)
+	}
+
+	d.fragments = d.fragments[:0]
+	return frame, d.timeDecoder.Decode(pkt.Timestamp), nil
+}