[linux-uvc-devel] guvcview ist not working after v3.16

Discussion:

Oleksij Rempel

2014-10-18 10:42:43 UTC

Hi all,

this is probably know issue, but i just noticed it. guvcview show only
black screen some where after kernel v3.16.
even with this branch which probably should fix it, i have only black
squere:
http://git.linuxtv.org/cgit.cgi/pinchartl/media.git/commit/?h=uvcvideo/fixes&id=a7f053c67c357c4b68c1be21976a1d464f97916b

on other hand, cheese, luvcview and skype work ok.
are there some one on it?

--
Regards,
Oleksij

Jörg-Volker Peetz

2014-10-22 09:42:39 UTC

Permalink

Post by Oleksij Rempel
Hi all,
this is probably know issue, but i just noticed it. guvcview show only
black screen some where after kernel v3.16.
even with this branch which probably should fix it, i have only black
http://git.linuxtv.org/cgit.cgi/pinchartl/media.git/commit/?h=uvcvideo/fixes&id=a7f053c67c357c4b68c1be21976a1d464f97916b
on other hand, cheese, luvcview and skype work ok.
are there some one on it?

It's the default capture method "mmap" of guvcview which does not work since
kernel 3.16. Try it with

$ guvcview -r 2

which switches to capture method "read".
--
Regards,
jvp.

Paulo Assis

2014-10-22 10:51:35 UTC

Permalink

Hi,
uvcvideo doesn't support read, only mmap, your camera is probably
using gspca or some other driver.

But like I said this is fixed in version 2.0.1:

http://sourceforge.net/projects/guvcview/

or for debian:

https://launchpad.net/~pj-assis/+archive/ubuntu/testing

Regards,
Paulo

Post by JÃ¶rg-Volker Peetz

It's the default capture method "mmap" of guvcview which does not work since
kernel 3.16. Try it with
$ guvcview -r 2
which switches to capture method "read".
--
Regards,
jvp.
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Jörg-Volker Peetz

2014-10-22 11:46:21 UTC

Permalink

Hi Paulo,

I'm using a self configured and compiled kernel 3.17.1 without gspca. "guvcview
-r 2" is working for me with guvcview version 1.7.3 (debian). In the file
"~/.config/guvcview/video0" in says now "cap_meth=2".

How can I find out which kernel driver actually is used by guvcview?

lsmod only shows uvcvideo and related modules.

Regards,
jvp.

Post by Paulo Assis
Hi,
uvcvideo doesn't support read, only mmap, your camera is probably
using gspca or some other driver.
http://sourceforge.net/projects/guvcview/
https://launchpad.net/~pj-assis/+archive/ubuntu/testing
Regards,
Paulo

Post by JÃ¶rg-Volker Peetz

Paulo Assis

2014-10-22 13:35:14 UTC

Permalink

Hi,
guvcview should display the device driver name when using the
--verbose option (or for version 2.0.0 something like --verbosity=2)

Note: It will display a lot of text so you should probably redirect
the output to a file.

Regards,
Paulo

Post by JÃ¶rg-Volker Peetz
Hi Paulo,
I'm using a self configured and compiled kernel 3.17.1 without gspca. "guvcview
-r 2" is working for me with guvcview version 1.7.3 (debian). In the file
"~/.config/guvcview/video0" in says now "cap_meth=2".
How can I find out which kernel driver actually is used by guvcview?
lsmod only shows uvcvideo and related modules.
Regards,
jvp.

Post by JÃ¶rg-Volker Peetz

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Monitor 10 servers for $9/Month.
Get alerted through email, SMS, voice calls or mobile push notifications.
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Jörg-Volker Peetz

2014-10-22 15:35:12 UTC

Permalink

Hi,

in the output I find among others

guvcview 1.7.3
video_device: /dev/video0
vid_sleep: 0
cap_meth: 2
...
yuyv: setting format to YUYV
capture method = 2
video device: /dev/video0
Device Node Path: /dev/video0
VID/PID: 0bda 5801
Realtek
2SF022
serial: 0x0001
busnum: 1
devnum: 2
vid:0bda
pid:5801
driver:uvcvideo
...

Which means?

guvcview seems to work fine, thank you for taking care, Paulo.

Regards,
jvp.

Post by Paulo Assis
Hi,
guvcview should display the device driver name when using the
--verbose option (or for version 2.0.0 something like --verbosity=2)
Note: It will display a lot of text so you should probably redirect
the output to a file.
Regards,
Paulo

Post by JÃ¶rg-Volker Peetz

It's the default capture method "mmap" of guvcview which does not work since
kernel 3.16. Try it with
$ guvcview -r 2
which switches to capture method "read".
--
Regards,
jvp.

Paulo Assis

2014-10-22 16:13:56 UTC

Permalink

Hi,
Oh! it looks like the device is using uvcvideo.
I remember Laurent saying it wasn't interested in adding read support
to uvcvideo since it was deprecated.
Maybe this comes from libv4l (mapping read calls to mmap ???).

Regards,
Paulo

Post by JÃ¶rg-Volker Peetz
Hi,
in the output I find among others
guvcview 1.7.3
video_device: /dev/video0
vid_sleep: 0
cap_meth: 2
...
yuyv: setting format to YUYV
capture method = 2
video device: /dev/video0
Device Node Path: /dev/video0
VID/PID: 0bda 5801
Realtek
2SF022
serial: 0x0001
busnum: 1
devnum: 2
vid:0bda
pid:5801
driver:uvcvideo
...
Which means?
guvcview seems to work fine, thank you for taking care, Paulo.
Regards,
jvp.

Post by JÃ¶rg-Volker Peetz

It's the default capture method "mmap" of guvcview which does not work since
kernel 3.16. Try it with
$ guvcview -r 2
which switches to capture method "read".
--
Regards,
jvp.

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Jörg-Volker Peetz

2014-10-22 16:39:31 UTC

Permalink

Hi,

on my HP Pavilion dv7 notebook with debian system, "mmap" works or not depending
on the kernel version. Therefore, I first thought it was a mere kernel problem.
I'm glad now that "guvcview -r 2" works with newer kernels.

Regards,
Jörg-Volker.

Post by Paulo Assis
Hi,
Oh! it looks like the device is using uvcvideo.
I remember Laurent saying it wasn't interested in adding read support
to uvcvideo since it was deprecated.
Maybe this comes from libv4l (mapping read calls to mmap ???).
Regards,
Paulo

Post by JÃ¶rg-Volker Peetz

It's the default capture method "mmap" of guvcview which does not work since
kernel 3.16. Try it with
$ guvcview -r 2
which switches to capture method "read".
--
Regards,
jvp.

------------------------------------------------------------------------------

LEFEBVRE Geoffroy

2014-10-22 18:50:17 UTC

Permalink

Please erase my Email from the list

Thanks

Post by JÃ¶rg-Volker Peetz

It's the default capture method "mmap" of guvcview which does not work since
kernel 3.16. Try it with
$ guvcview -r 2
which switches to capture method "read".
--
Regards,
jvp.

------------------------------------------------------------------------------