I don't personally use the camera/ptz functions in player, but this is a
pretty common question, so I'll try to help everyone out and write up a FAQ
for it. (Brian, Andrew, or whoever maintains the FAQ, feel free to grab
Q. I have a camera, how do I use it? How can I access the image data?
There are several options for accessing image data from a camera in Player:
1. Write a Player driver which reads the data directly from the camera.
2. Use the *EXPERIMENTAL* big message system to return the image data.
3. Use an external streaming system, like Quicktime RTSP, gstreamer, VideoLAN
The first is the "supported" way of accessing the camera. By building a driver
in Player, the need to transmit camera information via a network is
minimized. The Player server can process the image, extract whatever
information you require, and return that if necessary. That is how the
blobfinder and cmvision "virtual sensors" work.
The big message system (--enable-bigmess) allows the Player server to transmit
big messages (2MB) rather than the standard (8kB). This, combined with a
CameraProxy object in Player, will allow client programs to read the camera
frames on demand. Be aware that this may break existing binary clients, as it
changes the message size that the client expects. (Is this true guys?) A
recompile of all clients is necessary if Player is compiled and
--enable-bigmess is turned on or off. Note also that this will SEVERELY
increase your network traffic, and may slow down the Player server.
Setting up an external streaming server allows you to access the "live" video
feed using many other popular programs. Since the data is not travelling via
Player, there is no (???) impact on the performance of Player. Also,
streaming servers typically compress the images before sending, reducing the
network load somewhat. That said, there are no samples in Player/Stage to
show you how to do this, as it is completely outside of the project.
Searching the mailing lists for "camera" will bring up most of the previous
discussions of this matter.
With thanks to Nate, Andrew, Bradley, and Brian, who have answered this
question in different forms a number of times now...
On Friday 03 September 2004 17:08, Paul Osmialowski wrote:
> Hello Player/Stage users!
> I'm new here so please be patient.
> Recently I've discovered this project and I'm trying to look what it can
> do. I've installed Player on some PC with 878A-based PCI frame grabber.
> Then I've connected Sony EVID30 camera to it. I'm using following .cfg
> file: camera:0 (
> driver "camerav4l"
> device "/dev/video0"
> source 0
> norm "ntsc"
> width 320
> height 240
> depth 24
> ptz:0 (
> driver "sonyevid30"
> port "/dev/ttyS1"
> (at first I had problems with PTZ device, finally I've created my own
> Mac-style to PC-style serial cable and now it's OK. I'm using viewer.tk
> on some remote host to drive PTZ device and it works fine).
> I can't find how can I make use with the camera device. Is there any way
> to forward grabbed image to remote host and process it there?
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