v4l2sink with USB webcam gadget

[Will Kelleher]

Hi everyone,

I've been trying to use my TI Davinci hardware as a USB webcam gadget.
 I backported the webcam module to the 2.6.32 kernel and I can
compile/load it successfully.  This module creates a v4l2 output
device that can accept YUY2 and MJPEG formats.

When I run

gst-launch videotestsrc ! v4l2sink device=/dev/video1

I get

"ERROR: from element
/GstPipeline:pipeline0/GstVideoTestSrc:videotestsrc0: Could not
negotiate format"

I've tried a variety of other pipelines but they all produce the same error.

Does anyone have experience with sending output to this particular
module (g_webcam)?  Am I doing something obviously wrong?

Thanks,

Will Kelleher
Nuvixa, Inc.

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[Marco Ballesio]

Hi,

On Wed, Feb 9, 2011 at 9:17 PM, Will Kelleher <[hidden email]> wrote:

> Hi everyone,
>
> I've been trying to use my TI Davinci hardware as a USB webcam gadget.
>  I backported the webcam module to the 2.6.32 kernel and I can
> compile/load it successfully.  This module creates a v4l2 output
> device that can accept YUY2 and MJPEG formats.
>
> When I run
>
> gst-launch videotestsrc ! v4l2sink device=/dev/video1
>
> I get
>
> "ERROR: from element
> /GstPipeline:pipeline0/GstVideoTestSrc:videotestsrc0: Could not
> negotiate format"

probably you need to convert format/resolution/frame rate. If you want
to know what went wrong with your caps negotiation, use -m as an
option for gst-launch. If you want even more details, you can set
GST_DEBUG=GST_CAPS:3 (or more).

A a last note, adding an ffmpegcolorspace ! videoscale ! videorate (or
a subet of the pipe) may help you.

Regard

>
> I've tried a variety of other pipelines but they all produce the same error.
>
> Does anyone have experience with sending output to this particular
> module (g_webcam)?  Am I doing something obviously wrong?
>
> Thanks,
>
> Will Kelleher
> Nuvixa, Inc.
>
> ------------------------------------------------------------------------------
> The ultimate all-in-one performance toolkit: Intel(R) Parallel Studio XE:
> Pinpoint memory and threading errors before they happen.
> Find and fix more than 250 security defects in the development cycle.
> Locate bottlenecks in serial and parallel code that limit performance.
> http://p.sf.net/sfu/intel-dev2devfeb
> _______________________________________________
> gstreamer-devel mailing list
> [hidden email]
> https://lists.sourceforge.net/lists/listinfo/gstreamer-devel
>

------------------------------------------------------------------------------
The ultimate all-in-one performance toolkit: Intel(R) Parallel Studio XE:
Pinpoint memory and threading errors before they happen.
Find and fix more than 250 security defects in the development cycle.
Locate bottlenecks in serial and parallel code that limit performance.
http://p.sf.net/sfu/intel-dev2devfeb
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[David Schleef-2]

On Thu, Feb 10, 2011 at 09:15:49AM +0200, Marco Ballesio wrote:

> Hi,
>
> On Wed, Feb 9, 2011 at 9:17 PM, Will Kelleher <[hidden email]> wrote:
> > Hi everyone,
> >
> > I've been trying to use my TI Davinci hardware as a USB webcam gadget.
> >  I backported the webcam module to the 2.6.32 kernel and I can
> > compile/load it successfully.  This module creates a v4l2 output
> > device that can accept YUY2 and MJPEG formats.
> >
> > When I run
> >
> > gst-launch videotestsrc ! v4l2sink device=/dev/video1
> >
> > I get
> >
> > "ERROR: from element
> > /GstPipeline:pipeline0/GstVideoTestSrc:videotestsrc0: Could not
> > negotiate format"
>
> probably you need to convert format/resolution/frame rate. If you want
> to know what went wrong with your caps negotiation, use -m as an
> option for gst-launch. If you want even more details, you can set
> GST_DEBUG=GST_CAPS:3 (or more).

You're much better off debugging caps negotiation problems using:

  GST_DEBUG=capsdebug:3 gst-launch videotestsrc ! capsdebug ! v4l2sink



David



------------------------------------------------------------------------------
The ultimate all-in-one performance toolkit: Intel(R) Parallel Studio XE:
Pinpoint memory and threading errors before they happen.
Find and fix more than 250 security defects in the development cycle.
Locate bottlenecks in serial and parallel code that limit performance.
http://p.sf.net/sfu/intel-dev2devfeb
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[Clark, Rob]

On Wed, Feb 9, 2011 at 1:17 PM, Will Kelleher <[hidden email]> wrote:

> Hi everyone,
>
> I've been trying to use my TI Davinci hardware as a USB webcam gadget.
>  I backported the webcam module to the 2.6.32 kernel and I can
> compile/load it successfully.  This module creates a v4l2 output
> device that can accept YUY2 and MJPEG formats.
>
> When I run
>
> gst-launch videotestsrc ! v4l2sink device=/dev/video1
>

so maybe I am missing something here, but if it is a camera/input
device, I think you probably want to use v4l2src..  since v4l2sink is
for output (tv tuners, or hw overlay on some platforms)

ie. something like: gst-launch v4l2src ! autovideosink

BR,
-R

> I get
>
> "ERROR: from element
> /GstPipeline:pipeline0/GstVideoTestSrc:videotestsrc0: Could not
> negotiate format"
>
> I've tried a variety of other pipelines but they all produce the same error.
>
> Does anyone have experience with sending output to this particular
> module (g_webcam)?  Am I doing something obviously wrong?
>
> Thanks,
>
> Will Kelleher
> Nuvixa, Inc.
>
> ------------------------------------------------------------------------------
> The ultimate all-in-one performance toolkit: Intel(R) Parallel Studio XE:
> Pinpoint memory and threading errors before they happen.
> Find and fix more than 250 security defects in the development cycle.
> Locate bottlenecks in serial and parallel code that limit performance.
> http://p.sf.net/sfu/intel-dev2devfeb
> _______________________________________________
> gstreamer-devel mailing list
> [hidden email]
> https://lists.sourceforge.net/lists/listinfo/gstreamer-devel
>

------------------------------------------------------------------------------
The ultimate all-in-one performance toolkit: Intel(R) Parallel Studio XE:
Pinpoint memory and threading errors before they happen.
Find and fix more than 250 security defects in the development cycle.
Locate bottlenecks in serial and parallel code that limit performance.
http://p.sf.net/sfu/intel-dev2devfeb
_______________________________________________
gstreamer-devel mailing list
[hidden email]
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[venuthepower]

Hi Will Kelleher,

I am trying back port uvc gadget driver for davinci. I am able to build the driver but when i insert the driver my driver gets clash. can u give me some steps to port it back

Thanks in advance