[meta-freescale] [meta-fsl-arm] Using gstreamer on Nitrogen6x/SabreLite

Daiane Angolini daiane.list at gmail.com
Tue Mar 4 11:16:58 PST 2014

On Tue, Mar 4, 2014 at 12:03 PM, Gary Thomas <gary at mlbassoc.com> wrote:
> I have a SabreLite with the OV5642 camera.  I'd like to capture
> some video and display it on the screen.  Here's my gstreamer
> pipeline:
> gst-launch -e -vvv mfw_v4lsrc device=/dev/video0 num-buffers=100 typefind=true \
>    ! "video/x-raw-yuv, format=(fourcc)I420, width=640, height=480, framerate=(fraction)30/1" \
>    ! ffmpegcolorspace \
>    ! ximagesink
> What I don't understand is why the format from mfw_v4lsrc has to
> be I420 when the OV5642 [kernel] driver seems to only support YUYV
> (yuyv422)?

I don't remember exactly, and I'm out of office right now, but
mfw_v4lsrc is a way to access CSI camera using IPU processing

What I don't remember is what is exactly supported in IPU, but you can
see this on Reference Manual. And, remember there are several
approaches IPU can handles like pre-processors, scalers, and so on.
That's why mfw_v4lsrc may be limited.

As I know, you can use v4lsrc with a capture driver if your kernel has
this support.

> To further confuse, I can grab a frame like this:
>   yavta -fYUYV -s640x480 -F -c1 /dev/video0
> and the V4l2 subsystem tells me this sensor is YUYV:
>   root at nitrogen6x:~# v4l2-ctl -d /dev/video0 --list-formats
>   ioctl: VIDIOC_ENUM_FMT
>         Index       : 0
>         Type        : Video Capture
>         Pixel Format: 'YUYV'
>         Name        :
> Can someone explain this, please?
> --
> ------------------------------------------------------------
> Gary Thomas                 |  Consulting for the
> MLB Associates              |    Embedded world
> ------------------------------------------------------------
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