Android version of the libsdptransform C++ library exposing the same API. It wraps the C++ library up and is written by kotlin. It also uses fastjson to parse and write objects.
libsdptransform is a simple parser and writer of SDP. Defines internal grammar based on RFC4566 - SDP, RFC5245 - ICE, and many more.
Syntax: fun parse(sdp: String): SessionDescription
Parses an unprocessed SDP string and returns a SessionDescription object. SDP lines can be terminated on \r\n (as per specification) or just \n.
private val sdp = """
v=0
o=- 20518 0 IN IP4 203.0.113.1
s=
t=0 0
c=IN IP4 203.0.113.1
a=ice-ufrag:F7gI
a=ice-pwd:x9cml/YzichV2+XlhiMu8g
a=fingerprint:sha-1 42:89:c5:c6:55:9d:6e:c8:e8:83:55:2a:39:f9:b6:eb:e9:a3:a9:e7
m=audio 54400 RTP/SAVPF 0 96
a=rtpmap:0 PCMU/8000
a=rtpmap:96 opus/48000
a=ptime:20
a=sendrecv
a=candidate:0 1 UDP 2113667327 203.0.113.1 54400 typ host
a=candidate:1 2 UDP 2113667326 203.0.113.1 54401 typ host
m=video 55400 RTP/SAVPF 97 98
a=rtcp-fb:* nack
a=rtpmap:97 H264/90000
a=fmtp:97 profile-level-id=4d0028;packetization-mode=1
a=rtcp-fb:97 trr-int 100
a=rtcp-fb:97 nack rpsi
a=rtpmap:98 VP8/90000
a=rtcp-fb:98 trr-int 100
a=rtcp-fb:98 nack rpsi
a=sendrecv
a=candidate:0 1 UDP 2113667327 203.0.113.1 55400 typ host
a=candidate:1 2 UDP 2113667326 203.0.113.1 55401 typ host
a=ssrc:1399694169 foo:bar
a=ssrc:1399694169 baz
a=imageattr:97 send [x=1280,y=720] recv [x=1280,y=720] [x=320,y=180]
a=simulcast:send 1,~4;2;3
""".trimIndent()
val sessionDescription = SdpTransform().parse(sdp)Resulting sessionDescription is an object as follows:
{
"connection": {
"ip": "203.0.113.1",
"version": 4
},
"fingerprint": {
"hash": "42:89:c5:c6:55:9d:6e:c8:e8:83:55:2a:39:f9:b6:eb:e9:a3:a9:e7",
"type": "sha-1"
},
"icePwd": "x9cml/YzichV2+XlhiMu8g",
"iceUfrag": "F7gI",
"media": [
{
"candidates": [
{
"component": 1,
"foundation": "0",
"ip": "203.0.113.1",
"port": 54400,
"priority": 2113667327,
"transport": "UDP",
"type": "host"
},
{
"component": 2,
"foundation": "1",
"ip": "203.0.113.1",
"port": 54401,
"priority": 2113667326,
"transport": "UDP",
"type": "host"
}
],
"direction": "sendrecv",
"fmtp": [],
"payloads": "0 96",
"port": 54400,
"protocol": "RTP/SAVPF",
"ptime": 20,
"rtp": [
{
"codec": "PCMU",
"payload": 0,
"rate": 8000
},
{
"codec": "opus",
"payload": 96,
"rate": 48000
}
],
"type": "audio"
},
{
"candidates": [
{
"component": 1,
"foundation": "0",
"ip": "203.0.113.1",
"port": 55400,
"priority": 2113667327,
"transport": "UDP",
"type": "host"
},
{
"component": 2,
"foundation": "1",
"ip": "203.0.113.1",
"port": 55401,
"priority": 2113667326,
"transport": "UDP",
"type": "host"
}
],
"direction": "sendrecv",
"fmtp": [
{
"config": "profile-level-id=4d0028;packetization-mode=1",
"payload": 97
}
],
"imageattrs": [
{
"attrs1": "[x=1280,y=720]",
"attrs2": "[x=1280,y=720] [x=320,y=180]",
"dir1": "send",
"dir2": "recv",
"pt": "97"
}
],
"payloads": "97 98",
"port": 55400,
"protocol": "RTP/SAVPF",
"rtcpFb": [
{
"payload": "*",
"type": "nack"
},
{
"payload": "97",
"subtype": "rpsi",
"type": "nack"
},
{
"payload": "98",
"subtype": "rpsi",
"type": "nack"
}
],
"rtcpFbTrrInt": [
{
"payload": "97",
"value": 100
},
{
"payload": "98",
"value": 100
}
],
"rtp": [
{
"codec": "H264",
"payload": 97,
"rate": 90000
},
{
"codec": "VP8",
"payload": 98,
"rate": 90000
}
],
"simulcast": {
"dir1": "send",
"list1": "1,~4;2;3"
},
"ssrcs": [
{
"attribute": "foo",
"id": 1399694169,
"value": "bar"
},
{
"attribute": "baz",
"id": 1399694169
}
],
"type": "video"
}
],
"name": "",
"origin": {
"address": "203.0.113.1",
"ipVer": 4,
"netType": "IN",
"sessionId": 20518,
"sessionVersion": 0,
"username": "-"
},
"timing": {
"start": 0,
"stop": 0
},
"version": "0"
}No excess parsing is done to the raw strings because the writer is built to be the inverse of the parser. That said, a few helpers have been built in:
Syntax: fun parseParams(params: String): Map<String, Any>
Parses fmtp[index].config and others such as rid[index].params and returns an object with all the params in a key/value fashion.
NOTE: All the values are expressed as strings.
val config = sessionDescription.media[1].fmtp[0].config
val params = sdpTransform.parseParams(config)Resulting params is a map object as follows:
{
"packetization-mode": 1,
"profile-level-id": "4d0028"
}Syntax: fun parsePayloads(payloads: String): List<Int>
Returns a list with all the payload advertised in the corresponding m-line.
val payloadsString = sessionDescription.media[1].payloads
val payloads = sdpTransform.parsePayloads(payloadsString)Resulting payloads is a list of int elements as follows:
[ 97, 98 ]Syntax: fun parseImageAttributes(params: String): List<Map<String, Any>>
Parses Generic Image Attributes. Must be provided with the attrs1 or attrs2 string of a a=imageattr line. Returns an array of key/value objects.
// a=imageattr:97 send [x=1280,y=720] recv [x=1280,y=720] [x=320,y=180]
val attrs2 = sessionDescription.media[1].imageattrs[0].attrs2
val imageAttributes = sdpTransform.parseImageAttributes(attrs2)Resulting imageAttributes is a list of map as follows:
[
{ "x": 1280, "y": 720 },
{ "x": 320, "y": 180 }
]Syntax: fun parseSimulcastStreamList(streams: String): List<List<SimulcastStream>>
Parses simulcast streams/formats. Must be provided with the attrs1 or attrs2 string of the a=simulcast line.
Returns an array of simulcast streams. Each entry is an array of alternative simulcast formats, which are objects with two keys:
scid: Simulcast identifier (string)paused: Whether the simulcast format is paused (boolean)
// a=simulcast:send 1,~4;2;3
val streams = sessionDescription.media[1].simulcast.list1
val simulcastAttributes = sdpTransform.parseSimulcastStreamList(streams)Resulting simulcastAttributes is a list of list as follows:
[
[ { "scid": "1", "paused": false }, { "scid": "4", "paused": true } ],
[ { "scid": "2", "paused": false } ],
[ { "scid": "3", "paused": false } ]
]Syntax: fun write(sdp: SessionDescription): String
The writer is the inverse of the parser, and will need a struct equivalent to the one returned by it.
val newSdpStr = sdpTransform.write(sessionDescription) // session parsed aboveResulting newSdpStr is a string as follows:
v=0
o=- 20518 0 IN IP4 203.0.113.1
s=
c=IN IP4 203.0.113.1
t=0 0
a=ice-ufrag:F7gI
a=ice-pwd:x9cml/YzichV2+XlhiMu8g
a=fingerprint:sha-1 42:89:c5:c6:55:9d:6e:c8:e8:83:55:2a:39:f9:b6:eb:e9:a3:a9:e7
m=audio 54400 RTP/SAVPF 0 96
a=rtpmap:0 PCMU/8000
a=rtpmap:96 opus/48000
a=ptime:20
a=sendrecv
a=candidate:0 1 UDP 2113667327 203.0.113.1 54400 typ host
a=candidate:1 2 UDP 2113667326 203.0.113.1 54401 typ host
m=video 55400 RTP/SAVPF 97 98
a=rtpmap:97 H264/90000
a=rtpmap:98 VP8/90000
a=fmtp:97 profile-level-id=4d0028;packetization-mode=1
a=rtcp-fb:97 trr-int 100
a=rtcp-fb:98 trr-int 100
a=rtcp-fb:* nack
a=rtcp-fb:97 nack rpsi
a=rtcp-fb:98 nack rpsi
a=sendrecv
a=candidate:0 1 UDP 2113667327 203.0.113.1 55400 typ host
a=candidate:1 2 UDP 2113667326 203.0.113.1 55401 typ host
a=ssrc:1399694169 foo:bar
a=ssrc:1399694169 baz
a=imageattr:97 send [x=1280,y=720] recv [x=1280,y=720] [x=320,y=180]
a=simulcast:send 1,~4;2;3
The only thing different from the original input is we follow the order specified by the SDP RFC, and we will always do so.
git clone https://github.com/wolfhan/sdptransformAndroid.git
cd sdptransformAndroid/
gradlew createSdptransformLib
After creating the sdptranform library, you can run the app.
- Build the lib:
gradlew createSdptransformLib
Wolf Han github
Special thanks to Iñaki Baz Castillo, the author of the libsdptransform and Eirik Albrigtsen, the author of the sdp-transform.