# README
SDP go implementation
RFC 4566 SDP: Session Description Protocol in golang.
In alpha stage.
Examples
See examples folder.
Also there is online SDP example (temporary unavailable) that gets
RTCPeerConnection.localDescription.sdp
using WebRTC,
sends it to server, decodes as sdp.Session
and renders it on web page.
SDP example:
v=0
o=jdoe 2890844526 2890842807 IN IP4 10.47.16.5
s=SDP Seminar
i=A Seminar on the session description protocol
u=http://www.example.com/seminars/sdp.pdf
[email protected] (Jane Doe)
p=12345
c=IN IP4 224.2.17.12/127
b=CT:154798
t=2873397496 2873404696
r=7d 1h 0 25h
k=clear:ab8c4df8b8f4as8v8iuy8re
a=recvonly
m=audio 49170 RTP/AVP 0
m=video 51372 RTP/AVP 99
b=AS:66781
k=prompt
a=rtpmap:99 h263-1998/90000
Encode:
package main
import (
"net"
"time"
"fmt"
"github.com/gortc/sdp"
)
func main() {
var (
s sdp.Session
b []byte
)
// defining medias
audio := sdp.Media{
Description: sdp.MediaDescription{
Type: "audio",
Port: 49170,
Format: "0",
Protocol: "RTP/AVP",
},
}
video := sdp.Media{
Description: sdp.MediaDescription{
Type: "video",
Port: 51372,
Format: "99",
Protocol: "RTP/AVP",
},
Bandwidths: sdp.Bandwidths{
sdp.BandwidthApplicationSpecific: 66781,
},
Encryption: sdp.Encryption{
Method: "prompt",
},
}
video.AddAttribute("rtpmap", "99", "h263-1998/90000")
// defining message
m := &sdp.Message{
Origin: sdp.Origin{
Username: "jdoe",
SessionID: 2890844526,
SessionVersion: 2890842807,
Address: "10.47.16.5",
},
Name: "SDP Seminar",
Info: "A Seminar on the session description protocol",
URI: "http://www.example.com/seminars/sdp.pdf",
Email: "[email protected] (Jane Doe)",
Phone: "12345",
Connection: sdp.ConnectionData{
IP: net.ParseIP("224.2.17.12"),
TTL: 127,
},
Bandwidths: sdp.Bandwidths{
sdp.BandwidthConferenceTotal: 154798,
},
Timing: []sdp.Timing{
{
Start: sdp.NTPToTime(2873397496),
End: sdp.NTPToTime(2873404696),
Repeat: 7 * time.Hour * 24,
Active: 3600 * time.Second,
Offsets: []time.Duration{
0,
25 * time.Hour,
},
},
},
Encryption: sdp.Encryption{
Method: "clear",
Key: "ab8c4df8b8f4as8v8iuy8re",
},
Medias: []sdp.Media{audio, video},
}
m.AddFlag("recvonly")
// appending message to session
s = m.Append(s)
// appending session to byte buffer
b = s.AppendTo(b)
fmt.Println(string(b))
}
Decode:
package main
import (
"fmt"
"io"
"io/ioutil"
"log"
"os"
"github.com/gortc/sdp"
)
func main() {
name := "example.sdp"
if len(os.Args) > 1 {
name = os.Args[1]
}
var (
s sdp.Session
b []byte
err error
f io.ReadCloser
)
fmt.Println("sdp file:", name)
if f, err = os.Open(name); err != nil {
log.Fatal("err:", err)
}
defer f.Close()
if b, err = ioutil.ReadAll(f); err != nil {
log.Fatal("err:", err)
}
if s, err = sdp.DecodeSession(b, s); err != nil {
log.Fatal("err:", err)
}
for k, v := range s {
fmt.Println(k, v)
}
d := sdp.NewDecoder(s)
m := new(sdp.Message)
if err = d.Decode(m); err != nil {
log.Fatal("err:", err)
}
fmt.Println("Decoded session", m.Name)
fmt.Println("Info:", m.Info)
fmt.Println("Origin:", m.Origin)
}
Also, low-level Session struct can be used directly to compose SDP message:
package main
import (
"fmt"
"github.com/gortc/sdp"
)
func main() {
var (
s sdp.Session
b []byte
)
b = s.AddVersion(0).
AddMediaDescription(sdp.MediaDescription{
Type: "video",
Port: 51372,
Format: "99",
Protocol: "RTP/AVP",
}).
AddAttribute("rtpmap", "99", "h263-1998/90000").
AddLine(sdp.TypeEmail, "[email protected]").
AddRaw('ф', "ОПАСНО").
AppendTo(b)
// and so on
fmt.Println(string(b))
// Output:
// v=0
// m=video 51372 RTP/AVP 99
// a=rtpmap:99 h263-1998/90000
// [email protected]
// ф=ОПАСНО
}
Supported params
- v (protocol version)
- o (originator and session identifier)
- s (session name)
- i (session information)
- u (URI of description)
- e (email address)
- p (phone number)
- c (connection information)
- b (zero or more bandwidth information lines)
- t (time)
- r (repeat)
- z (time zone adjustments)
- k (encryption key)
- a (zero or more session attribute lines)
- m (media name and transport address)
TODO:
- Encoding
- Parsing
- High level encoding
- High level decoding
- Examples
- CI
- More examples and docs
- Online example
- io.Reader and io.Writer interop
- Include to high-level CI
Possible optimizations
There are comments // ALLOCATIONS: suboptimal.
and // CPU: suboptimal.
that indicate suboptimal implementation that can be optimized. There are often
a benchmarks for this pieces.
# Packages
No description provided by the author
# Functions
DecodeSession decodes Session from b, returning error if any.
NewDecoder returns Decoder for Session.
NTPToTime converts NTP timestamp to time.Time with special case for Zero time, that is interpreted as 0 timestamp.
TimeToNTP converts time.Time to NTP timestamp with special case for Zero time, that is interpreted as 0 timestamp.
# Constants
Possible values for <bwtype> defined in section 5.8.
Possible values for <bwtype> defined in section 5.8.
Attribute types as described in RFC 4566.
Attribute types as described in RFC 4566.
Attribute types as described in RFC 4566.
Attribute types as described in RFC 4566.
Attribute types as described in RFC 4566.
Attribute types as described in RFC 4566.
Attribute types as described in RFC 4566.
Attribute types as described in RFC 4566.
Attribute types as described in RFC 4566.
Attribute types as described in RFC 4566.
Attribute types as described in RFC 4566.
Attribute types as described in RFC 4566.
Attribute types as described in RFC 4566.
Attribute types as described in RFC 4566.
Attribute types as described in RFC 4566.
# Structs
ConnectionData is representation for Connection Data field.
DecodeError wraps Reason of error and occurrence Place.
Decoder decodes session.
Encryption wraps encryption Key and Method.
Line of SDP session.
Media is media description and attributes.
MediaDescription represents Media Description field value.
Message is top level abstraction.
Origin is field defined in RFC4566 5.2.
TimeZone is representation of <adjustment time> <offset> pair.
Timing wraps "repeat times" and "timing" information.
# Type aliases
Attributes is set of k:v.
Bandwidths is map of BandwidthsType and int (bytes per second).
BandwidthType is <bwtype> sub-field of Bandwidth field.
Medias is list of Media.
Session is set of Lines.
Type of SDP Line is exactly one case-significant character.