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Implementation of a gstreamer source

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Emmanuel Pacaud-2

Implementation of a gstreamer source

Hi,

I'm currently developing an industrial camera acquisition library,
Aravis.

http://git.gnome.org/browse/aravis/
http://blogs.gnome.org/emmanuel/category/aravis/

I'm now trying to write a gstreamer source element using this library.
And since I don't know much about gstreamer, I'm looking for some
advices for this work.

Aravis is using a pool of buffers, in which it stores complete raw
images, in different formats depending on the camera capabilities.

Is GstPushSrc the right base class for an Aravis source element ?

Does gstreamer provides elements which are able to understand a stream
of raw image buffers ?

Is there an existing gstreamer plugin similar to what I want to
implement ?

Thanks in advance,

Emmanuel.

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Josh Doe-2

Re: Implementation of a gstreamer source

Hello,
I am working on a very similar project. I have created a source element for the National Instruments IMAQ series of capture cards (Camera Link and LVDS).

Yes you want to use GstPushSrc since cameras are live sources, that is what I use for my niimaqsrc.

Most GStreamer elements work with raw data, depending on what format you're talking about. The majority of elements work in YUV, but you can always use ffmpegcolorspace to convert from raw gray or RGB to that.

I have a particular interest in high bit depth cameras, typically 12 to 16-bits per channel, though mostly a single channel (grayscale). There are very few elements right now that work with video/x-raw-gray,depth=16, including ffmpegcolorspace. I plan to write many elements to work with these higher bit depths. So far the only one I've written is a videolevels element which converts 16-bit to 8-bit given pairs of lower/upper input and output levels (linear stretch). I will also add auto-stretch and setting of a LUT. Later I would like to implement tone mapping algorithms to better take advantage of the higher bit depth.

If you'd like I can send you my implementation of the niimaqsrc element; at some point I plan to start an online repository if my work will allow it.

I am also very interested in your project because at some point I plan to start using GigE Vision and Firewire cameras.

Regards,
-Josh

On Mon, Apr 12, 2010 at 9:49 AM, Emmanuel Pacaud <[hidden email]> wrote:

Hi,

I'm currently developing an industrial camera acquisition library,
Aravis.

http://git.gnome.org/browse/aravis/
http://blogs.gnome.org/emmanuel/category/aravis/

I'm now trying to write a gstreamer source element using this library.
And since I don't know much about gstreamer, I'm looking for some
advices for this work.

Aravis is using a pool of buffers, in which it stores complete raw
images, in different formats depending on the camera capabilities.

Is GstPushSrc the right base class for an Aravis source element ?

Does gstreamer provides elements which are able to understand a stream
of raw image buffers ?

Is there an existing gstreamer plugin similar to what I want to
implement ?

Thanks in advance,

Emmanuel.

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Emmanuel Pacaud-2

Re: Implementation of a gstreamer source

Hi,

Le lundi 12 avril 2010 à 17:58 +0200, Josh D a écrit :
> I am working on a very similar project. I have created a source
> element for the National Instruments IMAQ series of capture cards
> (Camera Link and LVDS).
>
> Yes you want to use GstPushSrc since cameras are live sources, that is
> what I use for my niimaqsrc.

Nice to hear I'm on the right track...

> Most GStreamer elements work with raw data, depending on what format
> you're talking about. The majority of elements work in YUV, but you
> can always use ffmpegcolorspace to convert from raw gray or RGB to
> that.

I'm mainly interested in 8 bits gray for now.

> I have a particular interest in high bit depth cameras, typically 12
> to 16-bits per channel, though mostly a single channel (grayscale).
> There are very few elements right now that work with
> video/x-raw-gray,depth=16, including ffmpegcolorspace. I plan to write
> many elements to work with these higher bit depths. So far the only
> one I've written is a videolevels element which converts 16-bit to
> 8-bit given pairs of lower/upper input and output levels (linear
> stretch). I will also add auto-stretch and setting of a LUT. Later I
> would like to implement tone mapping algorithms to better take
> advantage of the higher bit depth.
>
> If you'd like I can send you my implementation of the niimaqsrc
> element;

That would be nice, as long as the license allows me to use it for a
LGPL development.

> at some point I plan to start an online repository if my work will
> allow it.
> I am also very interested in your project because at some point I plan
> to start using GigE Vision and Firewire cameras.

The current state or Aravis should make it usable for GigEVision
cameras. Firewire support is not implemented yet, and I probably won't
have time to work on it soon.

Regards,

Emmanuel.

> On Mon, Apr 12, 2010 at 9:49 AM, Emmanuel Pacaud <[hidden email]>
> wrote:
> Hi,
>
> I'm currently developing an industrial camera acquisition
> library,
> Aravis.
>
> http://git.gnome.org/browse/aravis/
> http://blogs.gnome.org/emmanuel/category/aravis/
>
> I'm now trying to write a gstreamer source element using this
> library.
> And since I don't know much about gstreamer, I'm looking for
> some
> advices for this work.
>
> Aravis is using a pool of buffers, in which it stores complete
> raw
> images, in different formats depending on the camera
> capabilities.
>
> Is GstPushSrc the right base class for an Aravis source
> element ?
>
> Does gstreamer provides elements which are able to understand
> a stream
> of raw image buffers ?
>
> Is there an existing gstreamer plugin similar to what I want
> to
> implement ?
>
> Thanks in advance,
>
> Emmanuel.
>
>
>
>
> ------------------------------------------------------------------------------
> Download Intel® Parallel Studio Eval
> Try the new software tools for yourself. Speed compiling, find
> bugs
> proactively, and fine-tune applications for parallel
> performance.
> See why Intel Parallel Studio got high marks during beta.
> http://p.sf.net/sfu/intel-sw-dev
> _______________________________________________
> gstreamer-devel mailing list
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> https://lists.sourceforge.net/lists/listinfo/gstreamer-devel
>

Arnout Vandecappelle

Re: Implementation of a gstreamer source

In reply to this post by Emmanuel Pacaud-2

On Monday 12 April 2010 15:49:54, Emmanuel Pacaud wrote:

> Is there an existing gstreamer plugin similar to what I want to
> implement ?

v4l2src also pre-allocates a buffer pool and works with that. Also, it is
able to negotiate caps between the camera (which may have several
resolutions etc) and the downstream elements. However, it has lots of other
complexities which are probably not relevant for you. udpsrc is a simpler
live source element that may be a bit closer to your arivissrc.

Regards,
Arnout

--
Arnout Vandecappelle arnout at mind be
Senior Embedded Software Architect +32-16-286540
Essensium/Mind http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium BE 872 984 063 RPR Leuven
LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle
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