[gst-devel] possibility to add another source pad to v4l2src

[Stefan Kost]

On 12.07.2010 05:40, Hu, Gang A wrote:
> Hi, Rob
> Thanks for your suggestion. It looks much easier to support dual stream in camerasrcbin. I plan to design the dual stream support like this.
> +-------------------------------------------------------------------------------------------------+
> | +------------------+     +----------------------+         Camerasrcbin         |
> | | v4l2camsrc   |    | other elements   |                             |
> |sink          src--- sink             src--------------------------------------->vfsrc
> | +------------------+     +----------------------+                             |
> |                                         +--------------+             |
> | +------------------+     +----------------------+     |  Tee     |             |
> | | v4l2camsrc   |     | other elements  |     |        tee_image--->image_src
> |sink          src-----sink            src-------sink        |             |
> | +------------------+     +----------------------+     +------------tee_video---->vidoe_src
> |                                                                  |
> +--------------------------------------------------------------------------------------------------+
> The first pipeline is for view finder and read data from /dev/vidoe0. The second pipeline is for image and video capture. It read data from /dev/video1.
> Is it possible to implement this design in camerabin? 
> Thanks.
>   

Thats the goal of the refactoring rob pointed out. Support more complex
source. Feedback on his branches are very welcome. Regarding your
camersrc, you can't easily subclass from pushsrc anymore, but you will
need to copy the implementation from there. Then you can either start
one task for each src-pad or use one task to drive all pads (for the
later you need to use an fdset to poll on multiple descriptors).

Stefan

> -----Original Message-----
> From: Rob Clark [mailto:rob at ti.com] 
> Sent: Monday, July 12, 2010 5:14 AM
> To: Discussion of the development of GStreamer
> Subject: Re: [gst-devel] possibility to add another source pad to v4l2src
>
> fyi, you might want to have a look at:
>
>   http://gstreamer.freedesktop.org/wiki/CameraBin
>
> I am in the process of refactoring camerabin to look more like this, so you could (for example) have a separate viewfinder port and capture port..  I have it working basically as the "future" picture on that wiki page looks, at least for video capture.  A bit needs to be done still for image capture, and some cleanup is still needed.  
>
> It doesn't quite help for what you want to do with v4l2src, but you could perhaps instead create a camsrc bin element containing multiple v4l2src elements and some glue logic to coordinate between them..  I think camerabin provides a better, higher level abstraction for applications to target for SoC's with advanced ISP's, compared to using v4l2src directly.
>
> BR,
> -R
>
> On Jul 11, 2010, at 12:55 AM, Hu, Gang A wrote:
>
>   
>> Hi,
>> In my platform, there are two data streams from the camera, one(/dev/video0) is for view finder and the other(/dev/video1) is for image and video capture.
>> My original design is to use a modified v4l2src and add one source pad tor v4l2src to support dual stream support. V4l2src read data from /dev/video0 and /dev/video1 and push the data stream to source pad0 and source pad1.
>> As V4l2src is inherited from pushsrc, and there is only one source pad in v4l2src, is it possible to add the other source pad without modifying the pushsrc? What should I take care if I need to design that way? How to set the getrange function for the new added source pad?
>> Many thanks.
>>  
>> Best Regards!
>> Hu Gang
>>  
>>  
>>  
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