gstreamer and v4l2

gstreamer and v4l2

[Ran Shalit]

Hello,

This is a bit offtopic, so I will understand if you rather not discuss that...

I am trying to use gstreamer with v4l2 vivi device,
I first check the capabilities with

gst-launch-1.0 --gst-debug=v4l2src:5 v4l2src device="/dev/video0" !
fakesink 2>&1

and it gives many capabilities such as the following:

video/x-raw-yuv, format=(string)YUY2, framerate=(fraction)[1/1000,
1000/1], width=(int) 640, height=(int)180, interlaced=(boolean)true

So I tried to run as following:

gst-launch-0.10 v4l2src device="/dev/video0" !
video/x-raw,width=640,height=180,framerate=30 ! autovideosink

But it keeps giving me auto negotiation error -4.
Trying to give other values did not help neither.

It is probaby more a gstreamer issue, but if someone is familiar and
can shed some light on this will will help.

Linux version is 3.10.0.

Regards,
Ran

Re: gstreamer and v4l2

[Hans Verkuil]

On 03/15/2016 08:10 AM, Ran Shalit wrote:
> Hello,
> 
> This is a bit offtopic, so I will understand if you rather not discuss that...
> 
> I am trying to use gstreamer with v4l2 vivi device,
> I first check the capabilities with
> 
> gst-launch-1.0 --gst-debug=v4l2src:5 v4l2src device="/dev/video0" !
> fakesink 2>&1
> 
> and it gives many capabilities such as the following:
> 
> video/x-raw-yuv, format=(string)YUY2, framerate=(fraction)[1/1000,
> 1000/1], width=(int) 640, height=(int)180, interlaced=(boolean)true
> 
> So I tried to run as following:
> 
> gst-launch-0.10 v4l2src device="/dev/video0" !
> video/x-raw,width=640,height=180,framerate=30 ! autovideosink
> 
> But it keeps giving me auto negotiation error -4.
> Trying to give other values did not help neither.
> 
> It is probaby more a gstreamer issue, but if someone is familiar and
> can shed some light on this will will help.

Actually, I suspect that vivi is the culprit. It had some non-standard
behavior that might mess up gstreamer. One of the (many) reasons it was
replaced with vivid.

Regards,

	Hans

Re: gstreamer and v4l2

[Ran Shalit]

On Tue, Mar 15, 2016 at 9:18 AM, Hans Verkuil <hverkuil@xs4all.nl> wrote:
> On 03/15/2016 08:10 AM, Ran Shalit wrote:
>> Hello,
>>
>> This is a bit offtopic, so I will understand if you rather not discuss that...
>>
>> I am trying to use gstreamer with v4l2 vivi device,
>> I first check the capabilities with
>>
>> gst-launch-1.0 --gst-debug=v4l2src:5 v4l2src device="/dev/video0" !
>> fakesink 2>&1
>>
>> and it gives many capabilities such as the following:
>>
>> video/x-raw-yuv, format=(string)YUY2, framerate=(fraction)[1/1000,
>> 1000/1], width=(int) 640, height=(int)180, interlaced=(boolean)true
>>
>> So I tried to run as following:
>>
>> gst-launch-0.10 v4l2src device="/dev/video0" !
>> video/x-raw,width=640,height=180,framerate=30 ! autovideosink
>>
>> But it keeps giving me auto negotiation error -4.
>> Trying to give other values did not help neither.
>>
>> It is probaby more a gstreamer issue, but if someone is familiar and
>> can shed some light on this will will help.
>
> Actually, I suspect that vivi is the culprit. It had some non-standard
> behavior that might mess up gstreamer. One of the (many) reasons it was
> replaced with vivid.
>
> Regards,
>
>         Hans

Hi Hans,

Thanks for the quick response.
Well... a minue after posting...
I made another try and just added videoconvert  (or ffmpegcolorspace)
before  autovideosink, and now it works just fine !
probably the unique size (640x180) from vivi is not supported in
autovideosink, without conversion in between.

So this how it works in my case , if it helps anyone with similar issue:

 gst-launch-0.10 v4l2src device="/dev/video0" !
video/x-raw,width=640,height=180,framerate=30 ! ffmpegcolorspace !
autovideosink

Thank you very much,
Ran

Re: gstreamer and v4l2

[Antonio Ospite]

On Tue, 15 Mar 2016 09:10:59 +0200
Ran Shalit <ranshalit@gmail.com> wrote:

> Hello,
> 
> This is a bit offtopic, so I will understand if you rather not discuss that...
> 
> I am trying to use gstreamer with v4l2 vivi device,
> I first check the capabilities with
> 
> gst-launch-1.0 --gst-debug=v4l2src:5 v4l2src device="/dev/video0" !
> fakesink 2>&1
> 
> and it gives many capabilities such as the following:
> 
> video/x-raw-yuv, format=(string)YUY2, framerate=(fraction)[1/1000,
> 1000/1], width=(int) 640, height=(int)180, interlaced=(boolean)true
>

A cleaner way to enumerate capabilities of a video device in GStreamer
is like that:

  gst-device-monitor-1.0 Video

on Debian distributions gst-device-monitor-1.0 is in the
gstreamer1.0-plugins-base-apps package.

> So I tried to run as following:
> 
> gst-launch-0.10 v4l2src device="/dev/video0" !
> video/x-raw,width=640,height=180,framerate=30 ! autovideosink
> 
> But it keeps giving me auto negotiation error -4.
> Trying to give other values did not help neither.

BTW, the need for videoconvert is more likely because of the pixelformat
rather than the frame dimensions.

Ciao ciao,
   Antonio

-- 
Antonio Ospite
http://ao2.it

A: Because it messes up the order in which people normally read text.
   See http://en.wikipedia.org/wiki/Posting_style
Q: Why is top-posting such a bad thing?

Re: gstreamer and v4l2

[Vladimir Zapolskiy]

On 15.03.2016 12:28, Antonio Ospite wrote:
> On Tue, 15 Mar 2016 09:10:59 +0200
> Ran Shalit <ranshalit@gmail.com> wrote:
> 
>> Hello,
>>
>> This is a bit offtopic, so I will understand if you rather not discuss that...
>>
>> I am trying to use gstreamer with v4l2 vivi device,
>> I first check the capabilities with
>>
>> gst-launch-1.0 --gst-debug=v4l2src:5 v4l2src device="/dev/video0" !
>> fakesink 2>&1
>>
>> and it gives many capabilities such as the following:
>>
>> video/x-raw-yuv, format=(string)YUY2, framerate=(fraction)[1/1000,
>> 1000/1], width=(int) 640, height=(int)180, interlaced=(boolean)true
>>
> 
> A cleaner way to enumerate capabilities of a video device in GStreamer
> is like that:
> 
>   gst-device-monitor-1.0 Video
> 
> on Debian distributions gst-device-monitor-1.0 is in the
> gstreamer1.0-plugins-base-apps package.

No, you add some redundant GStreamer app instead of using just
GStreamer framework internals, this is not a cleaner way.

>> So I tried to run as following:
>>
>> gst-launch-0.10 v4l2src device="/dev/video0" !
>> video/x-raw,width=640,height=180,framerate=30 ! autovideosink

According to the received caps use

* video/x-raw-yuv
* framerate=30/1
* and start from fakesink

>>
>> But it keeps giving me auto negotiation error -4.
>> Trying to give other values did not help neither.
> 
> BTW, the need for videoconvert is more likely because of the pixelformat
> rather than the frame dimensions.
> 

--
With best wishes,
Vladimir