[libcamera-devel] [RFC v1 1/7] py: cam.py: Fix multi camera capture without -C

[Kieran Bingham]

Quoting Tomi Valkeinen (2022-06-23 15:47:30)
> -C flag is supposed to affect only the camera that was previously
> defined in the arguments. That's not the case, and, e.g.:
> 
> cam.py -c2 -C -c3
> 
> causes camera 3 to start capturing, but it stops after the initial
> Requests have been completed.
> 
> Fix the issue by filtering out camera contexts that do not have -C
> defined.
> 
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen at ideasonboard.com>
> ---
>  src/py/cam/cam.py | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/src/py/cam/cam.py b/src/py/cam/cam.py
> index 2ae89fa8..733e9ae5 100755
> --- a/src/py/cam/cam.py
> +++ b/src/py/cam/cam.py
> @@ -434,6 +434,8 @@ def main():
>          if args.info:
>              ctx.do_cmd_info()
>  

As the tools are often used for reference or guidance to newcomers it
might be helpful to clarify this with a comment. Maybe the filtering is
more clear to someone who writes a lot more python ... but from a C
perspective it takes me a minute to identify what this line really
does.

       # Filter out contexts which don't need to run a capture
> +    contexts = [ctx for ctx in contexts if ctx.opt_capture > 0]
> +
>      if args.capture:

Should this be done on a per-context basis? - Can cam.py already capture
from multiple cameras at the same time?
Maybe the rest is in the code below that I haven't read yet.

But the filtering itself sounds fine independently:

Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>

>          state = CaptureState(cm, contexts)
>  
> -- 
> 2.34.1
>