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Software or hardware limitation?

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Software or hardware limitation?
« on: 30 / July / 2020, 15:47:40 »
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I currently have the Powershot SX70HS. At the moment, it's not supported by CHDK but as a keen developer, I would be willing to give porting CHDK a shot.

I am coming an issue where whenever I plug a HDMI cable into the camera, the camera disables the EVF and the screen on the camera. Based on some googling around, it seems as though there are cameras in the Powershot lineup that support output to the EVF whilst also having a HDMI output. My use case is using a USB capture card and recording video from that on my PC, whilst also taking photos at the same time on the camera. It isn't very helpful if there's a ~1 second latency on the output shown on my screen and my subject is very fast moving - so I'd want the EVF to work.

So that brings the question: is it a software limitation or a hardware limitation that stops the camera from outputting to the EVF and on the hdmi port at the same time? And are there any other better/alternative ways to take photos whilst in the middle of recording a video?

Kind regards

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Offline reyalp

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Re: Software or hardware limitation?
« Reply #1 on: 30 / July / 2020, 16:17:58 »
I currently have the Powershot SX70HS. At the moment, it's not supported by CHDK but as a keen developer, I would be willing to give porting CHDK a shot.
SX70 is a digic 8 camera, which for various reasons will make CHDK support difficult (see https://chdk.setepontos.com/index.php?topic=13530.0 and the current state of digic 7 support: https://chdk.setepontos.com/index.php?topic=13943.0, https://chdk.setepontos.com/index.php?topic=13773.0). Magic Lantern may be a better starting point: https://www.magiclantern.fm/forum/index.php?topic=23296.0

That said, if you are a developer with reverse engineering experience and sufficient time and interest, it's very likely that you can get *something* to run leveraging the existing knowledge from CHDK and magic lantern.

Quote
I am coming an issue where whenever I plug a HDMI cable into the camera, the camera disables the EVF and the screen on the camera. Based on some googling around, it seems as though there are cameras in the Powershot lineup that support output to the EVF whilst also having a HDMI output.
I'm not aware of any CHDK supported cameras which support this. Only a few (EOS M3, M10 and G5 X) support HDMI out in shooting mode at all.

Assuming the latency is in the capture process rather than the cameras HDMI output, some kind of HDMI splitter and additional monitor might be a more viable alternative.
Don't forget what the H stands for.

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Offline srsa_4c

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Re: Software or hardware limitation?
« Reply #2 on: 30 / July / 2020, 16:39:00 »
is it a software limitation or a hardware limitation that stops the camera from outputting to the EVF and on the hdmi port at the same time?
It's a firmware limitation. I'm only aware of one model among ML-supported cameras that supports simultaneous LCD and HDMI output, the EOS 5d mk III, with firmware 1.2.x or later. If not implemented in firmware, I'd guess it would be rather difficult to develop without documentation.
Assuming the latency is in the capture process rather than the cameras HDMI output, some kind of HDMI splitter and additional monitor might be a more viable alternative.
+1

BTW, it turned out that certain EOS firmware based PowerShots and EOS M models did keep Canon Basic scripting. Only proven to exist on two models, not on sx70 yet. CHDK related scripts will not run however, as a large number of key event procedures are missing.

Re: Software or hardware limitation?
« Reply #3 on: 30 / July / 2020, 18:20:13 »
Thank you both for the advice/information! I put a request into Canon and they said they would pass on my comments to the team RE the software limitation - whether that will happen or not is another matter... I will try playing around with a hdmi splitter. Interestingly, the eos webcam utility meets my needs entirely... but taking photos results in them entering the buffer and never being saved anywhere... We will see. Thanks again


 

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