and how can this be done in libgphoto2? that's the question

Try this INDI compatible INDIGO driver: github.com/indigo-astronomy/indigo/tree/..._drivers/ccd_gphoto2
It supports 5x Zoom and many more features. It was developed and tested with a 700D, so basically everything works even automatic mirror lockup etc...

Ok I just asked Thomas if he can add this feature to the INDI driver as well. Regarding the speed, I'm working on a new websocket based solution that should help with the frame rates. Now if I can finish the new Synscan driver...

Ok I feel stupid now since you are Thomas and the the developer behind this driver. Can something like this be done on the INDI driver side as well? Right now, JPEG frames are sent. Is this software zoom or a camera control feature?

Copello, thanks for the suggestion.
Unfortunately, I'm looking for a way of capturing a video stream of raw cropped/5x zoomed frames (like eos-movrec app does), and the INDIGO ccd gphoto2 driver provide only a feature for capturing cropped/5x zoomed preview stills, since it doesn't have the Streaming tab/feature.

Jasem,
I was checking the code from eos-movrec and I found some interesting things:
1- They also used gp_camera_capture_preview(...) for capturing from the Live View stream, but they employed a Mutex to control the update (memcpy() of the pointer data from gp_file_get_data_and_size() into the buffer frame) of the live stream buffer, and a file write control to try to stabilize the fps. Looks like this must be implemented at both INDI::StreamManager and driver side;
2- Instead of doing software cropping, like INDI Photo does, they used _gp_set_config_value_string(camera, "eoszoom", str_param, camera_context) and _gp_set_config_value_string(camera, "eoszoomposition", str_param, camera_context) to enable zoom and set the zoom/crop position features of the camera's Live View itself. According to this thread , only 1x and 5x zoom factors work, and, unfortunately, 10x zoom doesn't work. The equivalent command line call would be something like: gphoto2 --set-config eoszoom=5 eoszoomposition=640,320 --capture-preview

Andreok,

Thank you for your feedback. I will be done with implementing this feature today. Already started on it yesterday and found it to be straightforward actually to implement. Also, with the new websocket powered INDI drivers, I am getting around ~9-10 FPS.. before it was 5-6 FPS max. KStars nightly should have the updated interface and I'll post a video here later on what to expect.

The INDI GPhoto driver also uses now a dedicated thread for this which substantially improved the performance. These changes will boost the performance of all INDI CCD drivers. For V4L2 drivers, now I can get 30+ FPS in KStars

So what do you guys think of this? I think the interface is pretty simple to use?

It's actually a lot faster now.. sometimes I get 25fps from Canon live view. It's vast improvement over older driver!

Jasem,
This is great! Really handy for manual focusing!
The Preview from Ekos use the Streaming feature/tab from the Photo driver?
I'm asking this because I want to use the driver to capture planetary SER files for Lucky Imaging of the Live View frames of my DSLR.
Thanks,
Andre

In my case the Zoom Out button does not work. The frame rate remained the same as before. Am I missing something? I compiled indi and kstars from GIT a few minutes ago. The cam is connected locally.

Absolutely. I just recorded SER at 20 FPS perfectly fine. However, beware the file will be REALLY large. For 30 seconds or so, it's around 88MB.

Ok, toupcam did not compile. Have to figure this one out first...