Screen capture issue

[abailey]

I have two 1920x1200 monitors. I want to capture video from the second (non-primary) monitor.

In the Open Media, Capture Device dialog, I have screen:// mode selected, and under the Show More Options checkbox, I put this in the Edit Options box:

:screen-fps=5.000000 :screen-caching=300 :screen-left=1920

This works fine. If I want to do a more distributable resolution (set the second monitor resolution to 1280x720), this results in a large black patch in the output video (1920x1200 size, but only the top 1280x720 having the capture). I modify the options to

:screen-fps=5.000000 :screen-caching=300 :screen-width=1280 :screen-height=720 :screen-left=1920

but VLC is unable to open. Under Messages, I get:

screen error: subscreen region overflows the screen
main error: open of `screen://' failed

Removing the screen-left parameter makes it work, but it shows the top-left 1280x720 of my primary screen. I can put the screen-left param back in, and give it 700 (so that it falls completely in the primary), this works. As soon as it would go onto the second screen, it fails. I have tried using a different monitor resolutions and parameters, but they will all fail if they are both specified AND would capture any of the second screen.

I am using Windows 7 x64 SP1, with VLC 1.1.11. I also installed the latest nightly build (trunk-20120116-0103 win64), and this is still present.

Edit: If I keep the different resolutions, but put the secondary monitor to the left of the primary in the Windows' screen resolution dialog, and have VLC do this:

:screen-fps=5.000000 :screen-caching=300 :screen-width=1280 :screen-height=720 :screen-left=-1280

it works. Shouldn't it (logically) work if the secondary is right of the primary as well?

[VLC_help]

Does it help if you also define screen-top ?

The actual code is following

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if( p_sys->i_left + p_sys->i_width > p_sys->fmt.video.i_width || p_sys->i_top + p_sys->i_height > p_sys->fmt.video.i_height ) { msg_Err( p_demux, "subscreen region overflows the screen" ); free( p_sys ); return VLC_EGENERIC; }

http://git.videolan.org/?p=vlc.git;a=bl ... n/screen.c

EDIT:
And if you use Tools -> Messages (set Verbosity to 2) (open it before you open the Screen capture) it should print the screen width: ... which should tell the values of p_sys->fmt.video.i_width and p_sys->fmt.video.i_height

[abailey]

specifying screen-top=0 does not seem to help. Tried with verbosity 2. Secondary monitor to the right.

:screen-fps=5.000000 :screen-caching=300 :screen-width=1280 :screen-height=720 :screen-left=1920 :screen-top=0

main debug: processing request item screen:// node Playlist skip 0
main debug: resyncing on screen://
main debug: screen:// is at 0
main debug: starting new item
main debug: creating new input thread
main debug: Creating an input for 'screen://'
main debug: thread started
main debug: using timeshift granularity of 50 MiB
main debug: thread (input) created at priority 1 (../.././src/input/input.c:220)
main debug: using timeshift path 'C:\Users\PRAETO~1\AppData\Local\Temp'
main debug: `screen://' gives access `screen' demux `' path `'
main debug: creating demux: access='screen' demux='' path=''
main debug: looking for access_demux module: 1 candidate
screen debug: capturing subscreen top: 0, left: 1920, width: 1280, height: 720
screen debug: screen width: 1920, height: 1200, depth: 32
screen error: subscreen region overflows the screen
main debug: no access_demux module matching "screen" could be loaded
main debug: TIMER module_need() : 0.000 ms - Total 0.000 ms / 1 intvls (Avg 0.000 ms)
main debug: creating access 'screen' path=''
main debug: looking for access module: 0 candidates
main debug: no access module matched "screen"
main debug: TIMER module_need() : 0.000 ms - Total 0.000 ms / 1 intvls (Avg 0.000 ms)
main error: open of `screen://' failed: (null)
main debug: thread ended
main debug: dead input
main debug: thread times: real 0m0.001000s, kernel 0m0.000000s, user 0m0.000000s
main debug: TIMER input launching for 'screen://' : 2.000 ms - Total 2.000 ms / 1 intvls (Avg 2.000 ms)
main debug: changing item without a request (current 0/1)
main debug: nothing to play

[VLC_help]

It seems VLC doesn't see the second screen correctly, does the screen width part change if you put second monitor to the left?

[abailey]

It does not change if it's to the left.

[HPx]

Hi,

I'm facing the same problem.
VLC only detect my first screen.

Is there a workaround to bypass this control ?

I'm using Windows 7 with a Nvidia GTX460 card.

Thanks

[VLC_help]

Bypass would prolly require code changes.

[HPx]

But there is no way to capture the second screen ?

[VLC_help]

It should be possible if you combine the displays to one desktop, like AMD Eyefinity does.

[HPx]

Unfortunately, the span option has disappear in Windows 7 and nvidia doesn't provide similar feature as Eyefinity

I think it could be solved by code in VLC, because sometimes the capture subscreen can cover a part of the two screens but not whole area.
It's strange but very annoying in my case.

[VLC_help]

I think it could be solved by code in VLC, because sometimes the capture subscreen can cover a part of the two screens but not whole area.

Yes, this requires fixing.

[macin]

I have the same problem with an ATI Radeon HD 5700 card. It seems that if the parameters screen-width and screen-height are not set then they have the default values zero causing the following not being executed unless you specify _both_ parameters:

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147 if( p_sys->i_width > 0 && p_sys->i_height > 0 ) 148 msg_Dbg( p_demux, "capturing subscreen top: %d, left: %d, " 149 "width: %d, height: %d", 150 p_sys->i_top, 151 p_sys->i_left, 152 p_sys->i_width, 153 p_sys->i_height );

And similarly the check stated in a previous post will also be skipped if either width or height is omitted. So in summary only specify width OR height and you can bypass the check. This is also a bug that should be fixed as far as I can tell.

The screen width and height in my case is reported to be 1280x1024 which is the resolution of my primary display. There is a second and third display connected right to and below of the primary one. The secondary has also resolution 1280x1024 and the third one has 1920x1080. Calling vlc as follows shows a truncated part (1280x1080) of the third display:

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vlc.exe --screen-fps 25 --screen-top 1024 --screen-height 1080 screen://

It seems the origin of the coordinate system is in the upper-left corner of the primary display so the subscreen region overflow check is flawed too since it assumes that the extended display ranges from (0,0) to (total_width, total_height) which seems to be wrong at least on Windows.