crop filter stops working after zmq change height when crop is the last filter

[Michael Enke]

Summary of the bug:
How to reproduce:

% ffplay -f dshow -i video="Integrated Webcam" -vf hflip,zmq=b=tcp\\://127.0.0.1\\:13333,crop=w=in_w/2:h=in_h/2
ffplay version 2023-03-05-git-912ac82a3c-full_build-www.gyan.dev

When sending now a message to crop filter to change h (Parsed_crop_2 h in_h), the video display freezes.
Problem does not occur when

• changing w
• crop filter comes before zmq filter
• behind crop filter, another filter is appended (e.g. vflip)

As well, the zmq documentation is maybe wrong. It says: zmq must be inserted between two video filters
But it works even zmq is the last or the first video filter.

[Michael Enke]

log file created with -report option