Thanks Andy,
I’m running an HDMI feed out from a DSLR through the UltraStudio Mini Recorder to the computer via Thunderbolt. From there I’m using BlackSyphon to pipe the video into my main app that processes the loop.
I believe the loop process is pretty solid. I’ve run a GL shape through it and got the results I expected.
- Screen Shot 2018-02-15 at 2.21.28 PM.png (10.24 KiB) Viewed 4539 times
As for the time period to capturing a frame, I’m relying on the stock configuration of all the equipment in the chain. The HDMI sends interlaced 59.94, although I have experimented with Magic Lantern to manipulate the frame rate of the captured video. But even at 1 frame per second capture there is a break in the image:
- Screen Shot 2018-03-04 at 5.13.07 PM.png (177.53 KiB) Viewed 4539 times
Based on the graph I posted earlier, lead me to believe that the general time interval from line blanking was the issue. This is only a theory and I was hoping someone with more experience can confirm or refute this. As far as I know I am continuously capturing frames. I’m not sure that dropping frames is the solution. In a previous example I started drawing the B from the lower left corner, and by the second loop through there is already a gap. I think by dropping frames the gap would be more distinct, no?
As I was browsing through the SDK I found a few related features:
page 227:
BMDDeckLinkSupportsClockTimingAdjustment - True if this device supports clock timing adjustment (see bmdDeckLinkConfigClockTimingAdjustment).
pg 231
bmdDeckLinkConfigClockTimingAdjustment - Clock frequency adjustment for fine output control. The acceptable range is from -127 to 127 PPM (Parts Per Million).
pg 228
bmdDeckLinkConfigReferenceInputTimingOffset - Adjust genlock timing pixel offset. If the device supports wide genlock offset adjustment (see BMDDeckLinkSupportsFullFrameReferenceInput TimingOffset attribute) then the supported range is between +/- half the count of total pixels in the video frame. Otherwise the supported range is +/- 511.
pg 229
bmdDeckLinkConfigVANCSourceLine1Mapping - The configuration of up to three lines of VANC to be transferred to or from the active picture on capture or output. The acceptable range is between 0 and 30. A value of 0 will disable the capture of that line.
pg 231
bmdDeckLinkConfigClockTimingAdjustment - Clock frequency adjustment for fine output control. The acceptable range is from -127 to 127 PPM (Parts Per Million).
My challenge is that I’m such a novice at programming that it will probably take a few months (years?) to wrap my head around all this stuff… and then… there’s no guarantee that I would be successful. Additionally, I need to find out if the Mini Recorder supports these timing adjustments, or do I need to purchase a different device. Thanks for the feedback!