[Interest] About usb cameras

[Josiah Bryan]

I created a class I called "VideoSurfaceAdapter" which inherits from a
QAbstractVideoSurface which allows me access to the raw frames. See
https://code.google.com/p/livepro/source/browse/trunk/gfxengine/QtVideoSource.cpp
for
the code.

Basically, in supportedPixelFormats() I return the formats I'll support,
and then in present(...), I do the conversion using QImage - the code is
all in the link above.

I hope this helps - forgive me if I misunderstood your problem.


On Tue, Sep 17, 2013 at 9:52 AM, Jason H <scorp1us at yahoo.com> wrote:

> Thanks, but I am still not clear.
>
> If I subclass QAbstractVideoSurface  (video probe is out - I need it on
> Windows) How do I get it into a QImage/Pixmap?
> I am guessing that I would set the pixel format for it to be the same as
> for QImage? According to the that logic and the docs, there are a few
> formats that will work:
> Format_ARGB32, Format_ARGB32_Premultiplied, Format_RGB32, Format_RGB555,
> Format_ARGB8565_Premultiplied
>
> But will Qt do the conversion (if so how? lines of code please!). Do I
> tell the video source to give me a format? Does that format have to be
> supported by the device?
>
> I don't mind updating the screen, as I will be generating an overlay. and
> pushing that to the screen.
>
> Thanks!
>
>
>   ------------------------------
>  *From:* Lopes Yoann <Yoann.Lopes at digia.com>
> *To:* Jason H <scorp1us at yahoo.com>
> *Cc:* "evazquez at grm.uci.cu" <evazquez at grm.uci.cu>; "
> interest at qt-project.org" <interest at qt-project.org>
> *Sent:* Tuesday, September 17, 2013 7:18 AM
>
> *Subject:* Re: [Interest] About usb cameras
>
>  On Sep 16, 2013, at 5:46 PM, Jason H wrote:
>
>   Can someone tell me how to grab a frame and what is needed to be done
> to get to the point where I can do image processing easily?
>
>
> With the C++ API you can use QVideoProbe (
> http://qt-project.org/doc/qt-5.0/qtmultimedia/qvideoprobe.html). Though,
> with a camera source, it will currently work only on Linux with the
> GStreamer backend. The frames can be in any format, including an OpenGL
> texture, and you'll have to to convert it to a QImage yourself if it's what
> you want to do.
>
>  You can also subclass QAbstractVideoSurface (
> http://qt-project.org/doc/qt-5.0/qtmultimedia/qabstractvideosurface.html).
> It will work on all platforms and you will be able to specify the format of
> the received frames with supportedPixelFormats(). You will also have to
> take care of showing the frames on screen youself...
>
>  Yoann Lopes
> Senior Software Engineer - Digia, Qt
> Visit us on: http://qt.digia.com
>
>
>
> _______________________________________________
> Interest mailing list
> Interest at qt-project.org
> http://lists.qt-project.org/mailman/listinfo/interest
>
>


-- 
Josiah Bryan
765-215-0511
josiahbryan at gmail.com
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