Float video media type

[Michał Rudowicz]

Hi,

I'm developing an application that makes use of a thermal camera, where one of
the possible operating modes is giving me frames that are essentially made out
of floating point values. I've looked through the available raw video media
types [0], but didn't find any that would be appropriate, I've also checked
Media Types and Properties [1]. I've also found a bug 621553 in Bugzilla [2],
but looks like the floating point raw video media type was not added in the
end.

The data received from the camera is not compressed, therefore my understanding
is that the media type should be video/x-raw, and new format would have to be
introduced - but I am a beginner in the GStreamer topics, so I may be wrong.

What would be the preferred way to approach this? Thanks in advance for help.

[0]: https://gstreamer.freedesktop.org/documentation/additional/design \
     /mediatype-video-raw.html
[1]: https://gstreamer.freedesktop.org/documentation/plugin-development \
     /advanced/media-types.html?gi-language=c
[2]: https://bugzilla.gnome.org/show_bug.cgi?id=621553
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[Josh Doe]

On Fri, Jun 26, 2020 at 9:46 AM Michał Rudowicz <[hidden email]> wrote:

What would be the preferred way to approach this? Thanks in advance for help.

I created that issue (a decade ago!), and haven't really found a need for float, but that's because I'm usually working with raw data, and apply any radiometric calibrations (i.e., conversion to temperature) outside of GStreamer. I would probably just stick to the integer images and apply your own mapping after the fact. If you want to get the floating point values and still take advantage of GStreamer for processing, I'd probably just pick a min/max float value and stretch the float to be 16-bit uint (e.g., GRAY16_LE).

What interface/framegrabber does this camera use?

-Josh

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[Michał Rudowicz]

> What interface/framegrabber does this camera use?

It has its own shared library which provides methods that fill the array with
float values. I wanted to integrate it to the existing GStreamer application.

> I'd probably just pick a min/max float value and stretch the float to be
> 16-bit uint

The problem is, that documentation of the device doesn't exaclty say what
values can be expected. In theory I can assume that just the "expected"
temperature values will be there, and ignore the rest.

> apply any radiometric calibrations (i.e., conversion to temperature)
> outside of GStreamer.

That's another option that I was considering.

Thanks for the fast reply!
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[Josh Doe]

On Fri, Jun 26, 2020 at 10:51 AM Michał Rudowicz <[hidden email]> wrote:

> What interface/framegrabber does this camera use?

It has its own shared library which provides methods that fill the array with
float values. I wanted to integrate it to the existing GStreamer application.

I should have mentioned gst-plugins-vision [0] if you haven't found it before. Doesn't do anything with float values, but used for a lot of thermal cameras. You might find videolevels handy, which simply stretches 16-bit video to 8-bit.

[0]: https://github.com/joshdoe/gst-plugins-vision

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[Michał Rudowicz]

gst-plugins-vision sounds great, I will definitely check it out.
Thanks!
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