Vrecord Dropping Frames when using a Blackmagic Ultrastudio Recorder 3G

vrecord is dropping frames when recording using a Blackmagic Ultrastudio Recorder 3G. It appears to be the same frames every time, frame 1 and frame 14. This happens regardless of the capture format, and regardless of whether a concurrent MP4 is made.

```
[decklink @ 0x11f104870] Frame received (#1) - No input signal detected - Frames dropped 1
[aist#0:0/pcm_s32le @ 0x11de06a40] Guessed Channel Layout: 7.1
[libopenh264 @ 0x11de09fa0] [OpenH264] this = 0x0x600001c862e0, Warning:layerId(0) doesn't support profile(578), change to UNSPECIFIC profile
[libopenh264 @ 0x11de09fa0] [OpenH264] this = 0x0x600001c862e0, Warning:bEnableFrameSkip = 0,bitrate can't be controlled for RC_QUALITY_MODE,RC_BITRATE_MODE and RC_TIMESTAMP_MODE without enabling skip frame.
[decklink @ 0x11f104870] Frame received (#14) - Input returned - Frames dropped 2
```

I tried a capture in Blackmagic Media Express and it didn't report any dropped frames, so I think this might be a vrecord issue specifically.

A few times I saw that later frames dropped two, about a minute or two in, but I've been unable to recreate this. Will continue testing.