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

Gary Thomas gary at mlbassoc.com
Wed Mar 5 09:52:36 PST 2014

On 2014-03-05 10:44, Eric Nelson wrote:
> Hi Gary,
> On 03/04/2014 08:03 AM, Gary Thomas 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)?
>> 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        :
> This appears to be a bug in the video driver (mxc_v4l2_capture) with
> respect to enumeration (not a strong point for the drivers).
> The driver (mxc_v4l2_capture) appears to support a wide variety of
> pixel formats through the magic of the IPU.
> The mfw_v4lsrc plugin appears to be hard-coded to support only
> UYVY and I420 on i.MX6 though (and NV12 on i.MX51).
> Note that your pipeline is very expensive, and would benefit from
> using a sink that can support YUV natively (mfw_isink, mfw_v4lsink)
> or that can do the conversion in hardware (glimagesink).

Thanks.  I only used ximagesink as an example (one that also
works on the desktop) for others to see.  In the end, the video
will probably be packaged into some container format (.mp4) and/or
streamed, so those other methods don't help much.

Is it possible to use the v4l2src gstreamer element with this video?
I haven't been able to make that work at all...

Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world

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