[linux-uvc-devel] Ipevo Ziggi HD document camera - Libwebcam patch, focussing from software

[Mike <mik...@bt...>]

Hi all,
   Attached is a patch for libwebcam.c that fixes the "slightly buggy 
implementation of the V4L2_CTRL_FLAG_NEXT_CTRL flag" problem exhibited 
by the Ipevo Ziggi HD document camera.  I've also tested it with 
Logitech C920 and Pro9000 cameras (which don't exhibit the problem), 
doesn't break them.

This allows "manual" control of the Ziggi-HD's focus via uvcdynctrl, but 
it's a two-stage process - first turn off auto-focus, then set the 
manual focus value:

mike@mike-desktop:~$ uvcdynctrl -d video0 -s "Focus, Auto" 0
mike@mike-desktop:~$ uvcdynctrl -d video0 -s "Focus (absolute)" 60

Annoyingly, the auto-focus is done completely differently.  The Ziggi-HD 
is a compound USB device with three components - Video, Audio and HID 
(Human Interface Device); the HID component represents the buttons and 
slide-switch on the camera head, and is also used to trigger an 
auto-focus operation via USB.  I was able to get this working on Linux 
using HIDAPI (http://www.signal11.us/oss/hidapi) and its test GUI to 
send and receive HID reports, and Cheese to monitor the video from the 
camera.  To trigger an auto-focus operation, send a HID Output report, 5 
bytes long, data 0x02 0x4F 0x00 0x00 0x00.  You should see a 5-byte HID 
Input report being received (01 02 01 00 00) in response, then the 
auto-focus happening, then a second 5-byte Input report (01 02 02 00 00) 
when it's complete.

Hope this sparks a bit of interest in using the Ziggi-HD from FOS 
software - seems a decent bit of kit for the money.

Mike H.