BMDStreamingAPI.dll support multiple capture?

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Kazuo Notake

  • Posts: 1
  • Joined: Thu Jun 18, 2015 10:34 pm

BMDStreamingAPI.dll support multiple capture?

PostSat Jun 20, 2015 4:57 pm

I have tried multiple capture with H.264 Pro Recorder.
I connected two H.264 Pro Recorder to one PC.
camera1 --- [HDMI] --- H.264 Pro Recorder --- [USB2.0] -+- PC
camera2 --- [HDMI] --- H.264 Pro Recorder --- [USB2.0] -+

I programmed capture application using Blackmagic DeckLink SDK 10.4.
The IBMDStreamingDeviceNotificationCallback::StreamingDeviceArrived() method called twice, and found two H.264 Pro Recorder device.
So, set BMDStreamingH264InputCallback callback to each device, and call IBMDStreamingDeviceInput::StartCapture() method.
My application seemed to have properly good working, but sometime NALpacket lost.

I have question, BMDStreamingAPI.dll support multiple capture?
I wont to capture camera1 and camera2 image at the same time.

Michael Bunk

  • Posts: 8
  • Joined: Mon May 26, 2014 12:04 pm
  • Location: Leipzig, Germany

Re: BMDStreamingAPI.dll support multiple capture?

PostWed Sep 23, 2015 1:21 pm

I also tried this, but made the experience that it does not work to capture two streams in the same process. Having two processes capturing one stream each works.

JP da Conceicao

  • Posts: 9
  • Joined: Mon Sep 21, 2015 2:01 pm

Re: BMDStreamingAPI.dll support multiple capture?

PostSun Feb 11, 2018 7:34 pm

Bump for this - has anyone managed to get simultaneous streams from 2 h.264 pro recorders in 1 process? Is it theoretically possible?

Ian Morrish

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  • Joined: Sun Jan 18, 2015 9:24 pm
  • Location: New Zealand

Re: BMDStreamingAPI.dll support multiple capture?

PostMon Feb 12, 2018 3:58 am

For reliability you would be much better off running 2 instances of an app so that if one crashed it didn't impact the other channel. I have run 2 copies of MXPTiny concurrently without any problem (H.264 ProRecorder and TVS as input sources) on a PC with 2 different USB 3 hubs.
Ian Morrish
Video Integrated Scripting Environment
(Windows PowerShell with ATEM driver + more)

JP da Conceicao

  • Posts: 9
  • Joined: Mon Sep 21, 2015 2:01 pm

Re: BMDStreamingAPI.dll support multiple capture?

PostMon Feb 12, 2018 9:30 am

Cool, I'm going to go that route. thanks Ian.
For the benefit of anyone else that comes across this thread:

When trying to record from 2 blackmagics with 1 process, I would intermittently get strange error messages and behavior:
- "invalid sync byte" messages, and data no longer coming through
- divide by zero exceptions when calling IBMDStreamingH264NALPacket::GetDisplayTime in IBMDStreamingH264InputCallback::H264NALPacketArrived

I suspect the SDK wasn't designed with this is mind.

Running 2 instances of my software and controlling a different device with each, I'm not able to reproduce any of those problems.

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