I've started to look at using camera1394 for my Point Grey Firefly MV USB camera. This camera implements 1394-over-USB and seems to work fine with camera1394 as far as I can tell, with one exception: The timestamps on the output are incorrect. They are typically sometime in January 1970 :)
---
header:
seq: 191
stamp:
secs: 34
nsecs: 533856000
frame_id: /camera
Looking at the code it seems that the timestamp is generated using data from the camera:
image.header.stamp = ros::Time((double) frame->timestamp / 1000000.0);
I'm not sure why the timestamp is nonzero--it could just be from uninitialized memory. These cameras do have an option to output some kind of timestamp, and I have enabled it, but in their own tool ("FlyCapture2"), the "seconds" and "microseconds" fields are zero even with this option enabled. There are however some other fields, "1394 cycle time seconds", "1394 cycle time count", and "1394 cycle time offset" but this seems to be time since capture started, not since the epoch.
Anyhow the question is, has anyone else using these cameras found a way to have the true timestamp included in the image/camera_info header?
UPDATE: Here is what is printed when camera1394_node is started:
$ rosrun camera1394 camera1394_node _guid:=00b09d010090a878
[ INFO] [1299180874.481328850]: Found camera with GUID b09d010090a878
[ INFO] [1299180874.481629395]: camera model: Point Grey Research Firefly MV FMVU-03MTM
[ INFO] [1299180874.490429490]: [00b09d010090a878] opened: 640x480_mono8, 15 fps, 400 Mb/s
[ INFO] [1299180874.528790077]: feature exposure value not available from device
[ WARN] [1299180874.612162273]: [00b09d010090a878] calibration does not match video mode (publishing uncalibrated data)
Originally posted by Patrick Bouffard on ROS Answers with karma: 2264 on 2011-03-02
Post score: 4
Original comments
Comment by Patrick Bouffard on 2011-03-03:
Good point Eric, I hadn't considered that the ticket can have its own conversation thread! https://code.ros.org/trac/ros-pkg/ticket/4841
Comment by Eric Perko on 2011-03-03:
I'm in a favor of a parameter essentially for use_hardware_time. Best thing is likely to just open an enhancement ticket against camera1394 and then link to that ticket in an "answer" to this question. Implementation can be discussed there with iterations on a patch.
Comment by Patrick Bouffard on 2011-03-03:
Ok this commenting system is a bit annoying due to the character limit.. Also it probably makes more sense to move to ros-users (-developers?) or email to discuss implementation. I'll drop you a line Ken.
Comment by Patrick Bouffard on 2011-03-03:
Yeah that's what I was thinking. Maybe best to just have a parameter to force this behaviour (who knows, maybe even for some true 1394 cameras this might sometimes be the right thing to do--depends on what you are using the timestamp for I guess). I can contribute a patch.
Comment by Ken on 2011-03-03:
We could add an option to have camera1394 override frame->timestamp with the system time. I don't see any really good way to tell whether a camera is on USB, but we could try using camera->model. When you start camera1394 and it prints out the camera's model name, does that include "USB"?
Comment by Ken on 2011-03-03:
Having searched through the libdc1394 source code, I've found the places where frame->timestamp gets set for the native Linux 1394 module, the MacOS module and the juju firewire module, but there's nothing about timestamps in the usb module.