Editor’s Note: The VMR (Virtual Message Router) mentioned in this post is now Solace PubSub+.
In part 1 of this series of blog posts, I introduced the concepts of using Solace for video streaming. In this second installment of the live video streaming over Solace series, let’s take a look at a simple streaming demo application called BroadcastMe. It’s designed to show how live video streaming can be implemented over Solace. The usage scenario is to multicast video from a single broadcaster to multiple stream viewers. The source code can be downloaded from Github.
Live video streaming is a little different from conventional video file playback. Stream video is usually transported using MPEG transport stream (MPEG-TS, MTS or TS). Very briefly, a transport stream specifies a container format which describes how to encapsulate packetized elementary streams with error correction and stream synchronization features. Within the transport stream, there are a number of sub-streams. For instance, a transport stream can contain a main data stream of MPEG codec (such as mpeg2, mp4, h264), as well as any number of non-MPEG codecs (such as ACS, DTS audio) or even text information like electronic program guide. The transport stream is then wrapped at the IP layer using UDP or RTSP (Real Time Streaming Protocol) for IP network delivery.
As the method of encoding and decoding transport streams for video/live stream playback has matured over the past decade, it does not make sense to break what already works by modifying codec to fit into the Solace messaging ecosystem. A more non-intrusive way to apply Solace’s data movement technology to live video streaming is to focus at the network IP layer. Specifically, I am referring to a streaming codec agnostic way of wrapping the payload of the transport layer protocol (such as UDP, RTSP) with Solace’s Solace Message Format (SMF). Here, the UDP payloads are the transport stream containers.
So, instead of delivering the transport stream container via the UDP protocol between a broadcaster and stream viewers, let’s intercept the UDP packet streams and re-inject its payload, encapsulated in SMF, into Solace for delivery. This way, Solace’s data movement features can be exploited to address various data/stream delivery problems like fan-out efficiency, geographical content routing and caching or even WAN optimization.
BroadcastMe in its basic form is a proxy. It consists of two parts, an InputProxy and an OutputProxy. Typically, a live video stream will enter into Solace via InputProxy where it bridges the live stream source and Solace, and will exit Solace via OutputProxy where it bridges the stream viewer and Solace.
At the InputProxy, UDP data is read off from the socket and its content, i.e. the transport stream container, is then added as an attachment of an outgoing BytesXMLMessage (see snippets below). This is the encapsulation process.
// Read data off socket
dsocket.receive(packet);
data = new byte[packet.getLength()];
System.arraycopy(packet.getData(), packet.getOffset(), data, 0,
packet.getLength());
// Create SMF message and encapsulate
BytesXMLMessage msg = JCSMPFactory.onlyInstance().createMessage(BytesXMLMessage.class);
msg.writeAttachment(data);
if (mode.equals("persistent")) {
msg.setDeliveryMode(DeliveryMode.PERSISTENT);
} else {
// Everything else, even if wrong spelling, just default to direct.
msg.setDeliveryMode(DeliveryMode.DIRECT);
}
// Send message
prod.send(msg, topic);
At the OutputProxy, the attachment part of the received BytesXMLMessage is read out and used as the message body of outgoing UDP packets (see snippets below). This is the decapsulation process.
// Pass msg content to UDP stream
DatagramPacket packet = new DatagramPacket(message.getAttachmentByteBuffer().array(),
message.getAttachmentContentLength(), address, port);
// Decapsulated and send to UDP
try {
dsocket.send(packet);
} catch (Exception ex) {
System.err.println("Encountered an Exception... "; + ex.getMessage());
}
So, what about the source of the live video stream? Are there any changes required? No, there are no modification required at the source side. The InputProxy picks up the video feed just like a normal video stream viewer device would, though transport protocols like UDP or RTSP. This design is intentional.
Likewise, what about at the destination, i.e. at the viewing device? You don’t need to change anything at the destination either. The OutputProxy delivers the video feed just like a normal video source device would through transport protocol like UDP or RTSP.
To get BroadcastMe to showcase live video stream over Solace you will need:
ip-172-31-19-216# configure ip-172-31-19-216(configure)# routing ip-172-31-19-216(configure/routing)# create cspf neighbor ip-172-31-13-92 connect-via 52.56.121.135 ip-172-31-13-92# configure ip-172-31-13-92(configure)# routing ip-172-31-13-92(configure/routing)# create cspf neighbor ip-172-31-19-216 connect-via 52.221.59.15
ip-172-31-19-216# show cspf neighbor * Neighbor Ports State Cost Cost Uptime Data/Ctrl cfg act ---------------------------- ----------- -------- ---- ---- ---------------- ip-172-31-13-92 55555/—— Ok 100 100 0d 04h 41m 18s ip-172-31-13-92# show cspf neighbor * Neighbor Ports State Cost Cost Uptime Data/Ctrl cfg act ---------------------------- ----------- -------- ---- ---- ---------------- ip-172-31-19-216 55555/—— Ok 100 100 0d 04h 41m 26s
$ ./inputProxy 52.221.59.15:55555 default default channel/1 direct 1235 verbose Input initializing... Jan 25, 2017 10:49:21 PM com.solacesystems.jcsmp.protocol.impl.TcpClientChannel call INFO: Connecting to host 'orig=52.221.59.15:55555, host=52.221.59.15, port=55555' (host 1 of 1, smfclient 2, attempt 1 of 1, this_host_attempt: 1 of 1) Jan 25, 2017 10:49:21 PM com.solacesystems.jcsmp.protocol.impl.TcpClientChannel call INFO: Connected to host 'orig=52.221.59.15:55555, host=52.221.59.15, port=55555' (smfclient 2) Connected. Control-C to exit
./ffmpeg -f avfoundation -framerate 30 -video_size 640x480 -i "0" -f mpegts udp://localhost:1235
Under Linux environment, “video4linux2” should be passed in as the argument for -f and the input device (-i) normally defaults to /dev/video0.
$ ./outputProxy 52.56.121.135:55555 default default channel/1 127.0.0.1 1239 verbose OutputProxy initializing... Jan 25, 2017 10:49:23 PM com.solacesystems.jcsmp.protocol.impl.TcpClientChannel call INFO: Connecting to host 'orig=52.56.121.135:55555, host=52.56.121.135, port=55555' (host 1 of 1, smfclient 2, attempt 1 of 1, this_host_attempt: 1 of 1) Jan 25, 2017 10:49:24 PM com.solacesystems.jcsmp.protocol.impl.TcpClientChannel call INFO: Connected to host 'orig=52.56.121.135:55555, host=52.56.121.135, port=55555' (smfclient 2) Connected. Control-C to exit
ip-172-31-19-216# show smrp subscriptions Flags Legend: T - Destination Type (C=local-client, Q=local-queue R=remote-router) P - Subscription Persistence (P=persistent, N=non-persistent) R - Redundancy Type for Local Destinations (P=primary, B=backup S=static -=not-applicable) Message VPN : default (exported: Yes; 100% complete) Destination Name Flags BlkID DTO Subscription T P R Prio ------------------------ - - - ----- ---- ------------------------------------ #client C N S 0 P1 #MCAST/> #client C N S 0 P1 #SEMP/ip-172-31-19-216/> #client C N S 0 P1 #P2P/ip-172-31-19-216/#client/> #client C N S 0 P1 #P2P/v:ip-172-31-19-216/#client/> #client C N S 0 P1 #SEMP/v:ip-172-31-19-216/> ip-172-31-13-92 R N - 0 DA #MCAST/> ip-172-31-13-92 R N - 0 DA #SEMP/ip-172-31-13-92/> ip-172-31-13-92 R N - 0 DA #P2P/ip-172-31-13-92/#client/> ip-172-31-13-92 R N - 0 DA #P2P/v:ip-172-31-13-92/#client/> ip-172-31-13-92 R N - 0 DA #SEMP/v:ip-172-31-13-92/> v:ip-172-31-13-92 R N - 21 DA channel/1 ip-172-31-13-92# show smrp subscriptions Flags Legend: T - Destination Type (C=local-client, Q=local-queue R=remote-router) P - Subscription Persistence (P=persistent, N=non-persistent) R - Redundancy Type for Local Destinations (P=primary, B=backup S=static -=not-applicable) Message VPN : default (exported: Yes; 100% complete) Destination Name Flags BlkID DTO Subscription T P R Prio ------------------------ - - - ----- ---- ------------------------------------ #client C N S 0 P1 #MCAST/> #client C N S 0 P1 #SEMP/ip-172-31-13-92/> #client C N S 0 P1 #P2P/ip-172-31-13-92/#client/> #client C N S 0 P1 #P2P/v:ip-172-31-13-92/#client/> #client C N S 0 P1 #SEMP/v:ip-172-31-13-92/> #P2P/QTMP/v:ip-172-31-13 Q P P 21 DA channel/1 -92/29f6f3a8-08be-4014 -8e72-e205af594849 ip-172-31-19-216 R N - 0 DA #MCAST/> ip-172-31-19-216 R N - 0 DA #SEMP/ip-172-31-19-216/> ip-172-31-19-216 R N - 0 DA #P2P/ip-172-31-19-216/#client/> ip-172-31-19-216 R N - 0 DA #P2P/v:ip-172-31-19-216/#client/> ip-172-31-19-216 R N - 0 DA #SEMP/v:ip-172-31-19-216/>
The OutputProxy create a temporary queue (#P2P/QTMP/v:ip-172-31-13-92/29f6f3a8-08be-4014-8e72-e205af594849) and maps topic subscription “channel/1” to attract the messages.
ip-172-31-19-216# show cspf neighbor ip-172-31-13-92 stats Neighbor : ip-172-31-13-92 Connect Via : 52.56.121.135:55003 Control Port : unspecified Received Sent -------------------- -------------------- Total Messages 3399 6118 Control Messages 2486 2482 Data Messages 913 3636 Total Bytes 1380320 4010413 Control Bytes 461506 462290 Data Bytes 918814 3548123 Ingress (msg/sec) Egress (msg/sec) -------------------- -------------------- Current Rate (1 sec sample) 1 48 Average Rate (60 sec interval) 0 9 Ingress (byte/sec) Egress (byte/sec) -------------------- -------------------- Current Rate (1 sec sample) 181 44353 Average Rate (60 sec interval) 28 9824 Total Ingress Discards 0 Total Egress Discards 0 ip-172-31-13-92(admin)# show cspf neighbor ip-172-31-19-216 stats Neighbor : ip-172-31-19-216 Connect Via : 52.221.59.15:55003 Control Port : unspecified Received Sent -------------------- -------------------- Total Messages 7808 3396 Control Messages 2478 2483 Data Messages 5330 913 Total Bytes 5669019 1379594 Control Bytes 461491 460780 Data Bytes 5207528 918814 Ingress (msg/sec) Egress (msg/sec) -------------------- -------------------- Current Rate (1 sec sample) 43 1 Average Rate (60 sec interval) 26 0 Ingress (byte/sec) Egress (byte/sec) -------------------- -------------------- Current Rate (1 sec sample) 35315 181 Average Rate (60 sec interval) 25662 42 Total Ingress Discards 0 Total Egress Discards 0
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