dropping frames by using Decklink Duo

Hello,

I record using FFmpeg command line on DeckLink Duo device.

There is no issue when I start recording for 3 hours. But when I start to do another recording 1 min later after finishing the 3 hours recording, I have dropping frame.

good to mention that I use Black Magic DeckLink SDK function, (IDeckLinkInput::FlushStreams) , to flush the device buffer before start and after stop recording.

Is there anyone can help me out? Also, what the setting of the device should be?


Thanks in advance.