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

[Tomi Valkeinen]

On 24/06/2022 11:13, 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.

Ok, I'll add a comment.

>         # 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

This "if" just checks if there's any capturing to be done. The above 
works as args.capture is a dict of the capture parameters, but as 
Laurent commented, it's perhaps clearer to do "if contexts".

> from multiple cameras at the same time?

Yes, you can capture from multiple cameras and streams.

> 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
>>