[Bug 778438] New: Failed to get video stream from v4l2loopback device by using gstreamer 1.2.4 and gstreamer 1.8.2

[GStreamer (GNOME Bugzilla)]

https://bugzilla.gnome.org/show_bug.cgi?id=778438

            Bug ID: 778438
           Summary: Failed to get video stream from v4l2loopback device by
                    using gstreamer 1.2.4 and gstreamer 1.8.2
    Classification: Platform
           Product: GStreamer
           Version: unspecified
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: Normal
         Component: gstreamer (core)
          Assignee: gstreamer-bugs at lists.freedesktop.org
          Reporter: kienleong at live.com.my
        QA Contact: gstreamer-bugs at lists.freedesktop.org
     GNOME version: ---

I tried to get video stream from v4l2loopback device by using Ubuntu 14.04 LTS,
Ubuntu 15.10, and Ubuntu 16.04 LTS but only Ubuntu 15.10 worked. 

The procedure to reproduce this issue is as follow:
A USB webcam (Logitech c930e) is connected to laptop and refer as /dev/video0
ubuntu at ubuntu:~/Downloads/v4l2loopback$ ls /dev/video*
/dev/video0

A v4l2loopback device is created with the following modprobe command:
ubuntu at ubuntu:~/Downloads/v4l2loopback$ sudo modprobe v4l2loopback device=1

The loopback device is refer as /dev/video1
ubuntu at ubuntu:~/Downloads/v4l2loopback$ ls /dev/video*
/dev/video0 /dev/video1

For ubuntu 14.04.05 LTS
ubuntu at ubuntu:~/Downloads/v4l2loopback$ uname -a
Linux ubuntu 4.4.0-31-generic #50~14.04.1-Ubuntu SMP Wed Jul 13 01:07:32 UTC
2016 x86_64 x86_64 x86_64 GNU/Linux

ubuntu at ubuntu:~/Downloads/v4l2loopback$ gst-launch-1.0 --version
gst-launch-1.0 version 1.2.4
GStreamer 1.2.4
https://launchpad.net/distros/ubuntu/+source/gstreamer1.0

At 1st terminal
ubuntu at ubuntu:~/Downloads/v4l2loopback$ gst-launch-1.0 v4l2src
device=/dev/video0 ! video/x-raw, format=I420, framerate=30/1, width=640,
height=480 ! v4l2sink device=/dev/video1
Setting pipeline to PAUSED ...
libv4l2: error getting pixformat: Invalid argument
Pipeline is live and does not need PREROLL ...
Setting pipeline to PLAYING ...
New clock: GstSystemClock

At 2nd terminal
ubuntu at ubuntu:~$ gst-launch-1.0 v4l2src device=/dev/video1 ! video/x-raw,
format=I420, framerate=30/1, width=640, height=480 ! videoconvert ! xvimagesink
sync=false
Setting pipeline to PAUSED ...
Pipeline is live and does not need PREROLL ...
Setting pipeline to PLAYING ...
New clock: GstSystemClock
ERROR: from element /GstPipeline:pipeline0/GstV4l2Src:v4l2src0: Internal data
flow error.
Additional debug info:
gstbasesrc.c(2865): gst_base_src_loop ():
/GstPipeline:pipeline0/GstV4l2Src:v4l2src0:
streaming task paused, reason error (-5)
Execution ended after 0:00:00.028176082
Setting pipeline to PAUSED ...
Setting pipeline to READY ...
Setting pipeline to NULL ...
Freeing pipeline ...

For Ubuntu 15.10
ubuntu at ubuntu:~$ uname -a
Linux ubuntu 4.2.0-16-generic #19-Ubuntu SMP Thu Oct 8 15:35:06 UTC 2015 x86_64
x86_64 x86_64 GNU/Linux

ubuntu at ubuntu:~$ gst-launch-1.0 --version
gst-launch-1.0 version 1.6.0
GStreamer 1.6.3
https://launchpad.net/distros/ubuntu/+source/gstreamer1.0

At 1st terminal
ubuntu at ubuntu:~$ gst-launch-1.0 v4l2src device=/dev/video0 ! video/x-raw,
format=I420, framerate=30/1, width=640, height=480 ! v4l2sink
device=/dev/video1
Setting pipeline to PAUSED ...
libv4l2: error getting pixformat: Invalid argument
Pipeline is live and does not need PREROLL ...
Setting pipeline to PLAYING ...
New clock: GstSystemClock

At 2nd terminal
ubuntu at ubuntu:~$ gst-launch-1.0 v4l2src device=/dev/video1 ! video/x-raw,
format=I420, framerate=30/1, width=640, height=480 ! videoconvert ! xvimagesink
sync=false
Setting pipeline to PAUSED ...
Pipeline is live and does not need PREROLL ...
Setting pipeline to PLAYING ...
New clock: GstSystemClock
^Chandling interrupt.
Interrupt: Stopping pipeline ...
Execution ended after 0:00:03.668339317
Setting pipeline to PAUSED ...
Setting pipeline to READY ...
Setting pipeline to NULL ...
Freeing pipeline ...

For Ubuntu 16.04 LTS
ubuntu at ubuntu:~$ uname -a
Linux ubuntu 4.4.0-31-generic #50-Ubuntu SMP Wed Jul 13 00:07:12 UTC 2016
x86_64 x86_64 x86_64 GNU/Linux

ubuntu at ubuntu:~$ gst-launch-1.0 --version
gst-launch-1.0 version 1.8.2
GStreamer 1.8.2
https://launchpad.net/distros/ubuntu/+source/gstreamer1.0

At 1st terminal
ubuntu at ubuntu:~$ gst-launch-1.0 v4l2src device=/dev/video0 ! video/x-raw,
format=I420, framerate=30/1, width=640, height=480 ! v4l2sink
device=/dev/video1
Setting pipeline to PAUSED ...
libv4l2: error getting pixformat: Invalid argument
Pipeline is live and does not need PREROLL ...
Setting pipeline to PLAYING ...
New clock: GstSystemClock

At 2nd terminal
ubuntu at ubuntu:~$ gst-launch-1.0 v4l2src device=/dev/video1 ! video/x-raw,
format=I420, framerate=30/1, width=640, height=480 ! videoconvert ! xvimagesink
sync=false
Setting pipeline to PAUSED ...
Pipeline is live and does not need PREROLL ...
Setting pipeline to PLAYING ...
New clock: GstSystemClock
ERROR: from element /GstPipeline:pipeline0/GstV4l2Src:v4l2src0: Failed to
allocate a buffer
Additional debug info:
gstv4l2src.c(884): gst_v4l2src_create ():
/GstPipeline:pipeline0/GstV4l2Src:v4l2src0
Execution ended after 0:00:00.032129266
Setting pipeline to PAUSED ...
Setting pipeline to READY ...
Setting pipeline to NULL ...
Freeing pipeline ...

P.S: guvcview has no problem to open the v4l2loopback device /dev/video1 in
Ubuntu 14.04 LTS, Ubuntu 15.10, and Ubuntu 16.04 LTS

The v4l2loopback module is downloaded from
https://github.com/umlaeute/v4l2loopback

-- 
You are receiving this mail because:
You are the QA Contact for the bug.
You are the assignee for the bug.