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

[Tomi Valkeinen]

On 24/06/2022 11:28, Laurent Pinchart wrote:
> On Fri, Jun 24, 2022 at 09:13:53AM +0100, Kieran Bingham wrote:
>> 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:
> 
> Maybe
> 
>      if contexts:
> 
> would be clearer ?

Yes, indeed.

>> 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>
> 
> Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

Thanks!

  Tomi