Approaching buffer overrun

[semotta]

I've spc5xx webcam on FC4, zm 1.22.0 and the following warning on logs:
WAR [Approaching buffer overrun, consider slowing capture, simplifying analysis or increasing ring buffer size

Shared memory was increased: both /proc/sys/kernel/shmall and /proc/sys/kernel/shmmax are 134217728, which I think is far enough.

Monitor settings: Maximum fps: 3, palette 24 bits, Width x Heigth: 352 x 288 and
Image buffer size:10 you have to agree it's very conservative.

An odd thing: if I increase "image buffer size" to 11, monitor goes red and stops working:
ERR [Shared memory not initialised by capture daemon]

Is there any other setting which might be affecting?

Thanks,
Sergio

[zoneminder]

Increasing the image buffer size is the right thing to do as 10 is much too small but you nearly always have to do a full ZM restart to make sure this takes effect.