[FFmpeg-user] Issues deinterlacing DirectShow input with ffplay

[Alex]

I'm using ffplay as a live preview for my capture card, and I'm trying to use
the yadif filter in mode 1 (send_field) to deinterlace the 59.94i input to
59.94 fps.

Using this command works as expected:

  ffplay -f dshow -i video="SA7160 PCI, Analog 01 Capture" -vf yadif=1

However, if I try the same command with an audio device included, the frame
rate appears capped at 29.97 fps as if I were using mode 0 (send_frame):

  ffplay -f dshow -i video="SA7160 PCI, Analog 01 Capture":audio="SA7160 PCI,
  Analog 01 WaveIn" -vf yadif=1

Why does the filter only work properly when there is no audio device on the
input? Is there a workaround for this or is it a bug?

Here's a screen recording as a demonstration: https://streamable.com/p0v9rk
Console output is attached.

Alex
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