track.go

package gortsplib

import (
	"fmt"
	"strconv"
	"strings"

	psdp "github.com/pion/sdp/v3"

	"github.com/cobalt-robotics/gortsplib/pkg/url"
)

// Track is a RTSP track.
type Track interface {
	// ClockRate returns the track clock rate.
	ClockRate() int

	// GetControl returns the track control attribute.
	GetControl() string

	// SetControl sets the track control attribute.
	SetControl(string)

	// MediaDescription returns the track media description in SDP format.
	MediaDescription() *psdp.MediaDescription

	clone() Track
	url(*url.URL) (*url.URL, error)
}

func newTrackFromMediaDescription(md *psdp.MediaDescription) (Track, error) {
	control := func() string {
		for _, attr := range md.Attributes {
			if attr.Key == "control" {
				return attr.Value
			}
		}
		return ""
	}()

	rtpmapPart1, payloadType := func() (string, uint8) {
		rtpmap, ok := md.Attribute("rtpmap")
		if !ok {
			return "", 0
		}
		rtpmap = strings.TrimSpace(rtpmap)

		rtpmapParts := strings.Split(rtpmap, " ")
		if len(rtpmapParts) != 2 {
			return "", 0
		}

		tmp, err := strconv.ParseInt(rtpmapParts[0], 10, 64)
		if err != nil {
			return "", 0
		}
		payloadType := uint8(tmp)

		return rtpmapParts[1], payloadType
	}()

	if len(md.MediaName.Formats) == 1 {
		switch {
		case md.MediaName.Media == "video":
			switch {
			case md.MediaName.Formats[0] == "26":
				return newTrackJPEGFromMediaDescription(control)

			case md.MediaName.Formats[0] == "32":
				return newTrackMPEG2VideoFromMediaDescription(control)

			case rtpmapPart1 == "H264/90000":
				return newTrackH264FromMediaDescription(control, payloadType, md)

			case rtpmapPart1 == "H265/90000":
				return newTrackH265FromMediaDescription(control, payloadType, md)

			case rtpmapPart1 == "VP8/90000":
				return newTrackVP8FromMediaDescription(control, payloadType, md)

			case rtpmapPart1 == "VP9/90000":
				return newTrackVP9FromMediaDescription(control, payloadType, md)
			}

		case md.MediaName.Media == "audio":
			switch {
			case md.MediaName.Formats[0] == "0":
				return newTrackPCMUFromMediaDescription(control, rtpmapPart1)

			case md.MediaName.Formats[0] == "8":
				return newTrackPCMAFromMediaDescription(control, rtpmapPart1)

			case md.MediaName.Formats[0] == "14":
				return newTrackMPEG2AudioFromMediaDescription(control)

			case strings.HasPrefix(strings.ToLower(rtpmapPart1), "mpeg4-generic/"):
				return newTrackMPEG4AudioFromMediaDescription(control, payloadType, md)

			case strings.HasPrefix(rtpmapPart1, "opus/"):
				return newTrackOpusFromMediaDescription(control, payloadType, rtpmapPart1, md)
			}
		}
	}

	return newTrackGenericFromMediaDescription(control, md)
}

type trackBase struct {
	control string
}

// GetControl gets the track control attribute.
func (t *trackBase) GetControl() string {
	return t.control
}

// SetControl sets the track control attribute.
func (t *trackBase) SetControl(c string) {
	t.control = c
}

func (t *trackBase) url(contentBase *url.URL) (*url.URL, error) {
	if contentBase == nil {
		return nil, fmt.Errorf("Content-Base header not provided")
	}

	control := t.GetControl()

	// no control attribute, use base URL
	if control == "" {
		return contentBase, nil
	}

	// control attribute contains an absolute path
	if strings.HasPrefix(control, "rtsp://") {
		ur, err := url.Parse(control)
		if err != nil {
			return nil, err
		}

		// copy host and credentials
		ur.Host = contentBase.Host
		ur.User = contentBase.User
		return ur, nil
	}

	// control attribute contains a relative control attribute
	// insert the control attribute at the end of the URL
	// if there's a query, insert it after the query
	// otherwise insert it after the path
	strURL := contentBase.String()
	if control[0] != '?' && !strings.HasSuffix(strURL, "/") {
		strURL += "/"
	}

	ur, _ := url.Parse(strURL + control)
	return ur, nil
}