Re: Live view on Canon EOS M50

Hi Antonio,

On Sat, May 16, 2020 at 05:27:10PM +0200, Antonio Cuni wrote:
> Hello,
> I am having some troubles to control my Canon EOS M50 with gphoto2 (on
> Linux):
> $ gphoto2 --version
> gphoto2 2.5.20
> [...]
> gphoto2         2.5.20         gcc, popt(m), exif, cdk, aa, jpeg, readline
> libgphoto2      2.5.22         all camlibs, gcc, ltdl, EXIF
> libgphoto2_port 0.12.0         iolibs: disk ptpip serial usb1 usbdiskdirect
> usbscsi, gcc, ltdl, USB, serial without locking
> 
> What I would like to do is the following:
> 1. enable live view and get a stream of jpg frames to process
> 2. keep the camera's LCD screen on during the live view, and being able to
> control the various settings from the camera (ISO, speed, focus, etc)
> 
> I tried to connect my camera to a windows PC and control it using Canon EOS
> Utility: the "live view mode" of that program does exactly what I want,
> i.e. it displays a real time stream of images on the windows computer, but
> I can still control all the settings from the camera. So, this should prove
> that the camera is capable of doing this, I suppose.
> However, I did not manage to achieve the same with gphoto2. I tried to
> connect the camera both via USB and Wi-Fi, and I get the same results in
> both cases.
> 
> The first thing to note that as soon as gphoto2 connects to my camera, for
> example with gphoto2 --config, the LCD turns off and the camera buttons are
> not responding: I suppose this is the normal behavior and it's intended.
> When gphoto2 exists, the LCD is still black, but the buttons work; in
> particular, if I press the shutter the camera takes a picture, and if I
> press "Menu" I can enter the menu. Once I do exit the menu, the LCD works
> again and I can use the camera as normal.
> 
> The first things which I tried was "gphoto2 --capture-movie --stdout": this
> works, and I can get a real time stream of frames. However, as soon as I
> start gphoto2, the camera LCD turns off and I can no longer control my
> camera using any button.
> 
> Then, I inspected gphoto2 --config, and I found a setting which looks
> promising: /main/settings/output:
> /main/settings/output
> Label: Camera Output
> Readonly: 0
> Type: RADIO
> Current: Unknown value 0008
> Choice: 0 Off
> Choice: 1 TFT
> Choice: 2 PC
> Choice: 3 TFT + PC
> Choice: 4 Setting 4
> Choice: 5 Setting 5
> Choice: 6 Setting 6
> Choice: 7 Setting 7
> Choice: 8 Unknown value 0008
> Choice: 9 Unknown value 0009
> Choice: 10 Unknown value 000a
> Choice: 11 Unknown value 000b
> END
> 
> The setting "TFT + PC" looks exactly what I need, and indeed it seems to do
> something. The following command turns the LCD back on:
>     $ gphoto2 --set-config output="TFT + PC"
> 
> However, it seems I can't use it together with --capture-movie. I tried the
> following, but I get the same result as a bare "--capture-movie", i.e. the
> LCD turns off. Moreover, as soon as gphoto2 exits, /main/settings/output is
> set back to "Unknown value 0008":
>     $ gphoto2 --set-config output="TFT + PC" --capture-movie
>     CTRL-C
>     $ gphoto2 --get-config=output
>     Label: Camera Output
> 
>     [...]
>     Current: Unknown value 0008
> 
> I tried all of the possible "Camera Output" settings: same result with all
> of them, apart 000a and 000b which cause an "Error 70" in the camera, for
> which I have to remove the battery in order to have it working again.
> 
> The same happens also inside gphoto2 --shell:
> 
> gphoto2: {/tmp} /> capture-preview  # this turns the LCD OFF
> gphoto2: {/tmp} /> set-config-index output=3 # LCD back ON
> gphoto2: {/tmp} /> capture-preview # LCD OFF
> [etc...]
> 
> I attach the output of gphoto2 --list-all-config, in case it's useful.
> 
> Does anybody have any idea?
> Thanks in advance,
> Antonio

So, the "output" variable is key here.

One thing to know is that --capture-preview when it is first run, and also --set-config viewfinder=1
changes it.

We have decoded more values for "output" in the meantime (in libgphoto2 2.5.23 or later):

        { N_("Off"),            0, 0 }, /*On 5DM3, LCD/TFT is off, mirror down and optical view finder enabled */
        { N_("TFT"),            1, 0 },
        { N_("PC"),             2, 0 },
        { N_("TFT + PC"),       3, 0 },
        { N_("MOBILE"),         4, 0 },
        { N_("TFT + MOBILE"),   5, 0 },
        { N_("PC + MOBILE"),    6, 0 },
        { N_("TFT + PC + MOBILE"), 7, 0 },
        { N_("MOBILE2"),        8, 0 },
        { N_("TFT + MOBILE2"),  9, 0 },
        { N_("PC + MOBILE2"),   10, 0 },
        { N_("TFT + PC + MOBILE2"), 11, 0 },

So what you can try is:

	gphoto2 --capture-preview --set-config output="TFT + MOBILE2" --capture-movie=10s

or without update:

	gphoto2 --capture-preview --set-config output="Unknown value 0009" --capture-movie=10s

or other output= options.

On on my EOS M10 and SX720HS I currently have only:
	Current: PC
	Choice: 0 Off
	Choice: 1 MOBILE2
	Choice: 2 PC
so I cannot test :/

Ciao, Marcus