Hey Everyone!
Disclaimer: So i have read I think every post on Blackmagics forum about Decklink latency but dont really feel that the posts that I have read were defined well enough or helped me understand the Decklink cards well enough for my current issue, so here goes nothing.
The Setup: I have a camera input HD1080i50 (its an endoscope used in hospitals), its coupled to my computer which has the standard Decklink 4k card. The input signal is overlayed with an interface written in opencv. And the output signal is sent to a screen that desplays the signal in HD1080i50.
The Problem: I wish to reduce the loopthrough latency from my current 110ms (cirka) to less than 60ms. From when the frame is detected on the wire input to its done sending it out the wire ouput. The one other requirement is that I must be able to draw an overlay to the videostream. Im currently doing this with opencv via x86mem and the CPU. This overlay is not static.
What I have tried:
Using Blackmagic Decklink SDK 12.4 I have compiled the Inputloopthrough project with referencelock off and:
This gave latencies that looked like this:
Average latency: Input = 42.42 ms, Processing = 0.23 ms, Output = 69.47 ms
This is a total of around 110ms - this varries with maybe 20ms in total, which im assuming is in part because reference lock is not being used.
I have my main project which performs with the same amount of frames of latency as the Inputloopthrough project this tells me that drawing the overlay takes almost no time in comparison the input read time and the ouput write time. And so looking into using GPUdirect doesnt seem to be necessary for me at this moment.
Questions
1. Are these latency numbers the norm of the blackmagic decklink 4k cards in general or are there faster ones?
2. Are there any tweaks or properties that could help further reduce the latency related to the input and/or output latency (with minor or greater benefit)?
3. how much can I expect reference lock to reduce the latency by if I had that?
4. I dont need the audio channels...would removing that code for audio improve performance in a significant way?
5. If I have to look at other hardware solutions, is there any you would suggest in particular?
if you can answer any of these questions feel free to join the conversation. Thank you so much in advance!
Disclaimer: So i have read I think every post on Blackmagics forum about Decklink latency but dont really feel that the posts that I have read were defined well enough or helped me understand the Decklink cards well enough for my current issue, so here goes nothing.
The Setup: I have a camera input HD1080i50 (its an endoscope used in hospitals), its coupled to my computer which has the standard Decklink 4k card. The input signal is overlayed with an interface written in opencv. And the output signal is sent to a screen that desplays the signal in HD1080i50.
The Problem: I wish to reduce the loopthrough latency from my current 110ms (cirka) to less than 60ms. From when the frame is detected on the wire input to its done sending it out the wire ouput. The one other requirement is that I must be able to draw an overlay to the videostream. Im currently doing this with opencv via x86mem and the CPU. This overlay is not static.
What I have tried:
Using Blackmagic Decklink SDK 12.4 I have compiled the Inputloopthrough project with referencelock off and:
- BMDDisplayMode = bmdModeHD1080i50
BMDPixelFormat = bmdFormat10BitYUV
This gave latencies that looked like this:
Average latency: Input = 42.42 ms, Processing = 0.23 ms, Output = 69.47 ms
This is a total of around 110ms - this varries with maybe 20ms in total, which im assuming is in part because reference lock is not being used.
I have my main project which performs with the same amount of frames of latency as the Inputloopthrough project this tells me that drawing the overlay takes almost no time in comparison the input read time and the ouput write time. And so looking into using GPUdirect doesnt seem to be necessary for me at this moment.
Questions
1. Are these latency numbers the norm of the blackmagic decklink 4k cards in general or are there faster ones?
2. Are there any tweaks or properties that could help further reduce the latency related to the input and/or output latency (with minor or greater benefit)?
3. how much can I expect reference lock to reduce the latency by if I had that?
4. I dont need the audio channels...would removing that code for audio improve performance in a significant way?
5. If I have to look at other hardware solutions, is there any you would suggest in particular?
if you can answer any of these questions feel free to join the conversation. Thank you so much in advance!