- Posts: 12
- Joined: Mon Jul 16, 2018 7:29 pm
- Real Name: David Ibbitson
Wed Nov 20, 2019 10:17 pm
Hi,
I'm having a timing issue with playout on the 8k pro and I'm hoping some suggestions can be offered.
I'm playing out with mode bmdMode4k2160p5994 on subdevices 0 and 1 with synchronized playback. Display duration and timescale are 1001 and 60000 respectively.
After a great deal of debugging it's looking more and more like the driver is not coming back with ScheduledFrameComplete fast enough. Over time these small discrepancies accumulate and I end up with a large backlog of frames due to not being able to schedule fast enough. (I'm feeding the card from a live 59.94 rtmp source). Note that the frame complete flag is always bmdOutputFrameCompleted. I'm not getting late or dropped back from the driver.
I should note that I have also tested this with bmdModeHD1080p5994 and it seems to work very well. (allthough an occasional dropped frame from the card, which could be another issue).
I'm more than able to keep the device full -- it constantly has 4 frames buffered at any one time. I've also verified that my buffer copies to IDeckLinkMutableVideoFrames buffers are not the bottleneck.
Is there any advice or gotchas for feeding dual UHD @5994 to the 8k pro for output? Is there perhaps an bug in the driver with SDK 11.2?
Thanks,
David
I'm having a timing issue with playout on the 8k pro and I'm hoping some suggestions can be offered.
I'm playing out with mode bmdMode4k2160p5994 on subdevices 0 and 1 with synchronized playback. Display duration and timescale are 1001 and 60000 respectively.
After a great deal of debugging it's looking more and more like the driver is not coming back with ScheduledFrameComplete fast enough. Over time these small discrepancies accumulate and I end up with a large backlog of frames due to not being able to schedule fast enough. (I'm feeding the card from a live 59.94 rtmp source). Note that the frame complete flag is always bmdOutputFrameCompleted. I'm not getting late or dropped back from the driver.
I should note that I have also tested this with bmdModeHD1080p5994 and it seems to work very well. (allthough an occasional dropped frame from the card, which could be another issue).
I'm more than able to keep the device full -- it constantly has 4 frames buffered at any one time. I've also verified that my buffer copies to IDeckLinkMutableVideoFrames buffers are not the bottleneck.
Is there any advice or gotchas for feeding dual UHD @5994 to the 8k pro for output? Is there perhaps an bug in the driver with SDK 11.2?
Thanks,
David