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From: Ahmed on 24 Jun 2010 07:45
Alec Rogers <alec.rogers(a)mathworks.com> wrote in message <hi28k3$ipk$1(a)fred.mathworks.com>...
> Hi Corey,
>
> The Buffer block changes the size (and therefore the rate) of a signal.
> It does this in a constant way, and it only stores as much data
> as is necessary to perform the conversion.
>
> The Queue block, on the other hand, has ports that allow you to push and
> pop the inputs. So, in contrast to the Buffer block, it is more about
> signal storage than alteration of the rate and size of a signal.
>
> With respect to your model, and what might be happening with respect to
> the display, is it possibly explained by dropping UDP packets? In other
> words, does the "top portion" of the video frame that is sometimes
> erroneously displayed correspond to one UDP packet in size?
>
> Finally, if your interest is just buffering the signal so that you have
> a steady video frame rate, you might also be able to use a Delay block
> (although that will depend on your model).
>
> Regards,
> -alec
>
> Corey wrote:
> > Hello,
> >
> > Maybe I am in need of reading more fundamental programming / signal
> > processing background, deeper than Simulink help files, but.......can
> > anyone give a thorough description of the difference between the
> > Simulink Queue block and the Buffer block? I realize one has much more
> > control over the Queue block, but the fundamental difference(s) I am not
> > sure of. Using one vs the other seems to greatly affect my model's
> > operation though.
> >
> > I am trying to send video over a UDP connection (via the UDP Send and
> > Receive blocks).....using only buffers (to chunk the video signal into
> > acceptably-sized segments to fit into UDP packets, and reassemble the
> > video signal on the receive end) gets the video to display on the Video
> > Viewer, although incorrectly - the display tends to be jumpy and sort of
> > vertically scroll. Generally, some percentage of the bottom half of
> > each frame is also shown at the top portion of the frame...the
> > percentage seems fairly random. Also, using a Frame Rate Display block,
> > it shows the frame rate varying wildly as the simulation runs. However,
> > when using a Queue block somewhere in the signal chain, the frame rate
> > seems to stay within about 0.0001 frames-per-second of the desired 30Hz.
> >
> > I am wondering if some more intricate double-buffering is required, or
> > am I just missing some fundamental concepts of Simulink?
> >
> > Any help would be greatly appreciated.
> >
> > Thanks,
> > Corey

I am new to matlab and im also trying to transmit a live video stream using UDP in simulink... can u give me an idea as to how this can be done.... thanks..
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