Play V4l2 video source on framebuffer

[jamesM]

Hi
I installed Ubuntu server 20.04 (without GUI) on my desktop PC and also
installed video capture card on my PC.
i wanna play real time Pal camera frame(720*576 )on framebuffer but i cant



>>v4l2-ctl --all
Driver Info:
        Driver name      : tw686x
        Card type        : tw6864
        Bus info         : PCI:0000:01:00.0
        Driver version   : 5.4.94
        Capabilities     : 0x85200001
                Video Capture
                Read/Write
                Streaming
                Extended Pix Format
                Device Capabilities
        Device Caps      : 0x05200001
                Video Capture
                Read/Write
                Streaming
                Extended Pix Format
Priority: 2
Video input : 0 (Composite0: ok)
Video Standard = 0x0000b000
        NTSC-M/M-JP/M-KR
Format Video Capture:
        Width/Height      : 720/480
        Pixel Format      : 'UYVY' (UYVY 4:2:2)
        Field             : Interlaced
        Bytes per Line    : 1440
        Size Image        : 691200
        Colorspace        : SMPTE 170M
        Transfer Function : Default (maps to Rec. 709)
        YCbCr/HSV Encoding: Default (maps to ITU-R 601)
        Quantization      : Default (maps to Limited Range)
        Flags             :
Streaming Parameters Video Capture:
        Capabilities     : timeperframe
        Frames per second: 30.000 (30/1)
        Read buffers     : 3

User Controls

                     brightness 0x00980900 (int)    : min=-128 max=127
step=1 default=0 value=0 flags=slider
                       contrast 0x00980901 (int)    : min=0 max=255 step=1
default=100 value=100 flags=slider
                     saturation 0x00980902 (int)    : min=0 max=255 step=1
default=128 value=128 flags=slider
                            hue 0x00980903 (int)    : min=-128 max=127
step=1 default=0 value=0 flags=slider


>>gst-launch-1.0 v4l2src device="/dev/video0" !
"video/x-raw,width=640,height=576,format=(string)YUY2" !
fbdevsink="/dev/fb0"

 WARNING:errorneous pipeline:could not link v4l2src0 to fbdevsink0 ,
fbdevsink0 cant handle
video/x-raw,width=(int)720,height=(int)576,(string)YUY2





It seems gstreamer pipeline need some filters  would you please help me what
kind of filters should i use?



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[Nicolas Dufresne-5]

Le mercredi 31 mars 2021 à 15:08 -0500, jamesM a écrit :
> Hi
> I installed Ubuntu server 20.04 (without GUI) on my desktop PC and also
> installed video capture card on my PC.
> i wanna play real time Pal camera frame(720*576 )on framebuffer but i cant

Can you define what "on framebuffer" means to you ? It's been a long time that
the Linux kernel have deprecate the FrameBuffer interface in favour of DRM/KMS.
Are you referring to this legacy ?

>
>
>
> > > v4l2-ctl --all
> Driver Info:
> Driver name      : tw686x
> Card type        : tw6864
> Bus info         : PCI:0000:01:00.0
> Driver version   : 5.4.94
> Capabilities     : 0x85200001
> Video Capture
> Read/Write
> Streaming
> Extended Pix Format
> Device Capabilities
> Device Caps      : 0x05200001
> Video Capture
> Read/Write
> Streaming
> Extended Pix Format
> Priority: 2
> Video input : 0 (Composite0: ok)
> Video Standard = 0x0000b000
> NTSC-M/M-JP/M-KR
> Format Video Capture:
> Width/Height      : 720/480
> Pixel Format      : 'UYVY' (UYVY 4:2:2)
> Field             : Interlaced
> Bytes per Line    : 1440
> Size Image        : 691200
> Colorspace        : SMPTE 170M
> Transfer Function : Default (maps to Rec. 709)
> YCbCr/HSV Encoding: Default (maps to ITU-R 601)
> Quantization      : Default (maps to Limited Range)
> Flags             :
> Streaming Parameters Video Capture:
> Capabilities     : timeperframe
> Frames per second: 30.000 (30/1)
> Read buffers     : 3
>
> User Controls
>
>                      brightness 0x00980900 (int)    : min=-128 max=127
> step=1 default=0 value=0 flags=slider
>                        contrast 0x00980901 (int)    : min=0 max=255 step=1
> default=100 value=100 flags=slider
>                      saturation 0x00980902 (int)    : min=0 max=255 step=1
> default=128 value=128 flags=slider
>                             hue 0x00980903 (int)    : min=-128 max=127
> step=1 default=0 value=0 flags=slider
>
>
> > > gst-launch-1.0 v4l2src device="/dev/video0" !
> "video/x-raw,width=640,height=576,format=(string)YUY2" !
> fbdevsink="/dev/fb0"
>
>  WARNING:errorneous pipeline:could not link v4l2src0 to fbdevsink0 ,
> fbdevsink0 cant handle
> video/x-raw,width=(int)720,height=(int)576,(string)YUY2

Perhaps you should read a bit more about GStreamer and constructing pipelines ?
In this case, you are missing a color conversion, since a framebuffer is always
in RGB colorspace (e.g. videoconvert). Also fbdevsink= is a syntax error. You
probably meant to write fbdevsink device=...

If you care about performance, use kmssink or glimagesink, they can both display
without a video server (except on NVIDIA proprietary driver, which does not
implement the required bits).

>
>
>
>
>
> It seems gstreamer pipeline need some filters  would you please help me what
> kind of filters should i use?
>
>
>
> --
> Sent from: http://gstreamer-devel.966125.n4.nabble.com/
> _______________________________________________
> gstreamer-devel mailing list
> [hidden email]
> https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel

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