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

Hi.
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.
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Michael Bunk

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  • 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.
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JP da Conceicao

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  • 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?
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Ian Morrish

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  • 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.
Regards,
Ian Morrish
Video Integrated Scripting Environment
(Windows PowerShell with ATEM driver + more)
https://ianmorrish.wordpress.com
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JP da Conceicao

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  • 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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