Issue capturing with DeckLink Mini Recorder

Ask software engineering and SDK questions for developers working on Mac OS X, Windows or Linux.
  • Author
  • Message
Offline

Zhong Yu

  • Posts: 2
  • Joined: Mon Feb 16, 2015 2:28 am

Issue capturing with DeckLink Mini Recorder

PostMon Feb 16, 2015 2:41 am

I am using a Decklink Mini Recorder to capture HDMI signals in Win7, and it works for a 720p@60Hz source from STB. When I change another STB which sends 1080i@50Hz HDMI, however, the Media Express showed previews as if it were through a purple filter. The black background is now purple, and the other colors seems to be mixed with purple. Could anybody tell me the reason?

In addtion, there is something I need verification. Are all interlaced fields combined into a whole frame and send to the SDK, meaning that the data I captured are guarenteed to be a frame no matter the source is progressive or interlaced?
Offline

Kevin Ross

  • Posts: 4
  • Joined: Mon Feb 16, 2015 4:16 am

Re: Issue capturing with DeckLink Mini Recorder

PostFri Feb 20, 2015 6:39 am

Zhong Yu wrote:I am using a Decklink Mini Recorder to capture HDMI signals in Win7, and it works for a 720p@60Hz source from STB. When I change another STB which sends 1080i@50Hz HDMI, however, the Media Express showed previews as if it were through a purple filter. The black background is now purple, and the other colors seems to be mixed with purple. Could anybody tell me the reason?


Someone more knowledgeable than me will have to answer this, but this sounds like a colorspace issue. Maybe RGB vs. YUV?

In addtion, there is something I need verification. Are all interlaced fields combined into a whole frame and send to the SDK, meaning that the data I captured are guarenteed to be a frame no matter the source is progressive or interlaced?


Yes. Both fields of an interlaced signal are combined into a single frame, and given to you combined. Meaning for a 1080i source, you will receive frames that are 1080 lines tall, not 540. However, it isn't deinterlaced. You'll still need to use your favorite deinterlacing algorithm if you want a 1080p result.

Hope this helps!
-- Kevin
Offline

Zhong Yu

  • Posts: 2
  • Joined: Mon Feb 16, 2015 2:28 am

Re: Issue capturing with DeckLink Mini Recorder

PostThu Feb 26, 2015 1:51 am

Kevin Ross wrote:
Zhong Yu wrote:I am using a Decklink Mini Recorder to capture HDMI signals in Win7, and it works for a 720p@60Hz source from STB. When I change another STB which sends 1080i@50Hz HDMI, however, the Media Express showed previews as if it were through a purple filter. The black background is now purple, and the other colors seems to be mixed with purple. Could anybody tell me the reason?


Someone more knowledgeable than me will have to answer this, but this sounds like a colorspace issue. Maybe RGB vs. YUV?

In addtion, there is something I need verification. Are all interlaced fields combined into a whole frame and send to the SDK, meaning that the data I captured are guarenteed to be a frame no matter the source is progressive or interlaced?


Yes. Both fields of an interlaced signal are combined into a single frame, and given to you combined. Meaning for a 1080i source, you will receive frames that are 1080 lines tall, not 540. However, it isn't deinterlaced. You'll still need to use your favorite deinterlacing algorithm if you want a 1080p result.

Hope this helps!
-- Kevin


Thanks for your reply, but I need an answer to the first problem. I believe it should not be a colorspace problem, as I mentioned, the Media Express showed a purple filtered image.

Return to Software Developers

Who is online

Users browsing this forum: No registered users and 2 guests