Blackmagic SRT

[bchah]

Blackmagic has updated their entire ATEM switcher line, now with SRT.

The SRT settings in the documentation do work, but there are two issues:

1. It does not work with SignedPolicy. The signature calculation seems to be affected by the way the ATEM sends in the SRT parameters so the original signature does not work.
2. The streaming settings XML for the ATEM needs to be manually edited and re-uploaded to change the stream ID, which is too complicated for most end-users

With the new update, all Blackmagic switchers have an interface for SRT that lets you put in a 'Server' and 'Key' value, without the requirement of creating a definition in the streaming settings XML. But how are these values sent to OME? Here is what I discovered.

In this example, we are setting the server with the 'key' being our intended stream ID of abc123:

On the OME side, we receive this string of arguments to the SRT Provider:

#!::u=abc123,bmd_uuid=b0d6667f-ef5e-47a8-88c3-125af516ebae,bmd_name=ATEM Mini Pro

This is actually a common method of providing SRT parameters, using #!:: followed by a comma separated list. So in OME all we need is the ability to parse the ID out of this string... A regex like this could cover it:

/#!::[^,]*=([^,]*)/

I tried to do this in my control server but unfortunately it is the SRT Provider that first receives the request and it does not get sent to the control server. Here is what the SRT Provider gets:

[2024-06-11 14:53:24.163] I [SPSRT-s9999:47102] SrtProvider | srt_provider.cpp:203  | The SRT client has connected :  [398914620] [#!::u=abc123,bmd_uuid=b0d6667f-ef5e-47a8-88c3-125af516ebae,bmd_name=ATEM Mini Pro]
[2024-06-11 14:53:24.163] I [SRT:RcvQ:w1:47104] SRT | core.cpp@SRT:11117 | @398952112: listen ret: -1 - conclusion
[2024-06-11 14:53:24.163] E [SPSRT-s9999:47102] SrtProvider | srt_provider.cpp:230  | SRT's streamid streamid must be in the following format, percent encoded. srt://{host}[:port]/{app}/{stream}?{query}={value} : #!::u=abc123,bmd_uuid=b0d6667f-ef5e-47a8-88c3-125af516ebae,bmd_name=ATEM Mini Pro
[2024-06-11 14:53:24.164] I [SPSRT-s9999:47102] SrtProvider | srt_provider.cpp:342  | SrtProvider::OnDisonnected :  [#!::u=abc123,bmd_uuid=b0d6667f-ef5e-47a8-88c3-125af516ebae,bmd_name=ATEM Mini Pro]
[2024-06-11 14:53:24.164] I [SRT:RcvQ:w1:47104] SRT | queue.cpp@SRT:1432 | managed the connection request from: 192.168.65.1:20614 result:waveahand
[2024-06-11 14:53:24.164] I [SRT:RcvQ:w1:47104] SRT | queue.cpp@SRT:1413 | request from: 192.168.65.1:59497 to agent:398952112
[2024-06-11 14:53:24.164] I [SRT:RcvQ:w1:47104] SRT | queue.cpp@SRT:1432 | managed the connection request from: 192.168.65.1:59497 result:waveahand
[2024-06-11 14:53:24.165] I [SRT:RcvQ:w1:47104] SRT | queue.cpp@SRT:1413 | request from: 192.168.65.1:59497 to agent:398952112
[2024-06-11 14:53:24.165] I [SRT:RcvQ:w1:47104] SRT | core.cpp@SRT:2069 | cmd=1(HSREQ) len=12 vers=0x10500 opts=0xbf delay=7
[2024-06-11 14:53:24.165] I [SRT:RcvQ:w1:47104] SRT | core.cpp@SRT:11117 | @398952112: listen ret: -1 - conclusion
[2024-06-11 14:53:24.165] I [SRT:RcvQ:w1:47104] SRT | queue.cpp@SRT:1432 | managed the connection request from: 192.168.65.1:59497 result:waveahand
[2024-06-11 14:53:24.166] E [SPSRT-s9999:47102] SRT | api.cpp@SRT:1133 | 14:53:24.165546/SPSRT-s9999*E:SRT.cn: srt_accept: no pending connection available at the moment

To my friends at Airensoft, would you consider working to add support for this other format of sending the stream ID? I think this might also solve the SignedPolicy issue. The ATEM series is one of the most popular streaming encoders on earth. It works great with RTMP already including SignedPolicy, and equally robust SRT support is very close.

As always, I have a stack of hardware here so happy to send tests or try different params as needed to assist with this.

[getroot]

Does this work for you?
11bf881

[bchah]

Thank you very much for this! I am eager to test but Launchpad is down so my build pipeline is broken. Will let you know as soon as it comes back.

[bchah]

Tested with the OME Docker dev image and this is working! Thank you very much @getroot 🎉

[getroot]

Oh good.

Could you update the documentation below? I don't have Blackmagic.

https://airensoft.gitbook.io/ovenmediaengine/live-source/srt-beta#blackmagic-web-presenter