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Dynamic vs. Dynamo ? How do they differ?

Joe HebertJoe Hebert Junior MemberPosts: 2,154
Does anyone know exactly what the difference is between a dynamic image and a dynamo image? They are setup the same way but they do act differently.

If I set up a dynamic image with a path to a radar map at weather.com and give a refresh rate of 0, the map only refreshes when the dynamic image is first shown, or when you tell it to refresh, or if the panel goes to sleep and then wakes up while the dynamic image is in view.

However, if I setup a dynamic image with a path to a CGI calling for an IP camera with the same refresh rate of 0, the dynamic image can update an 800x600 picture at 24 fps.

What make the ?dynamo? stream? The video server can?t push it out because the dynamic image is configured for HTTP; I have to assume the dynamic image must be pulling it. So why does something like a radar map only get pulled once with a refresh rate of 0 but the ?dynamo? pulls like a mad man with the same refresh rate of 0? How does it do dat? Does the response from the CGI somehow tell the dynamic image to open up a UDP port for the stream or something like that? Inquiring minds would like to know.

Thanks.

Comments

  • viningvining X Member Posts: 4,358
    " For DynaMo, however, the panel needs to access only the M-JPEG stream, not the entire HTML page served by the camera/server by default. "

    " **Dynamo being a streaming application does not have a refresh rate. It establishes communications and begins receiving the stream. "

    I guess with the MJPEG and the .cgi in the file path it knows it should attempt to open a stream.
  • Simple answer

    DynaMo = push. Refresh depends on source encoder and speed of the network.
    Dynamic = pull. The panel requests the image.
  • Joe HebertJoe Hebert Junior Member Posts: 2,154
    B_Clements wrote:
    DynaMo = push. Refresh depends on source encoder and speed of the network.
    Dynamic = pull. The panel requests the image.
    I meant to follow up on this earlier and forgot. Pushing is not possible with HTTP since it?s connectionless; the client has to initiate contact. After doing some testing with Ethereal, I?ve come to the conclusion that Dynamo and Dynamic are setup the same because they are indeed the same exact thing. I got hung up trying to figure out how the ?Dynamo? was able to get a steam of images with a refresh rate of 0 (assuming it had to be a bunch of pulls or a change in protocol) and the ?Dynamic? only got one image with a refresh rate of 0 (one pull.)
    The setup process is essentially identical to that for setting up other Dynamic Images. It includes three easy steps:
    The TPD4 help file is somewhat misleading. The process is not essentially identical, it is absolutely identical.

    I believe the following to be true:

    Dynamic Image = 1 pull (1 GET)

    Dynamo Image = 1 pull (1 GET)

    In both cases the touch panel requests the image. The difference is the GET (the filename) for a Dynamo is a CGI call and the CGI creates the stream by returning a file that never ends. The CGI keeps making the file bigger and bigger and the ?Dynamic/Dynamo? looks at it like one big file and keeps pulling it until the connection is dropped or told to drop.

    I?m not sure how the Dynamo knows how to display each frame. I imagine the data itself must describe it and that the second and subsequent frames are drawn in the same manner as the first.

    I do wonder what the Dynamic Image control actually is. Is it a Java applet?
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