Parsing question

[Jaime Magiera]

Hey folks,

I'm new to the list, but have been working with OSC for a couple years  
now. I included the ability to navigate QuickTime VR movies with the  
P5 Virtual Reality Glove using OSC. It's pretty cool. You can control  
QTVR over a network.

I had been relying on third-party OSC frameworks to parse out the  
data. However, now I'm attempting to build a full client/server  
framework. One thing that I never noticed before about the format: The  
argument types are consecutive, with the values aligned afterward.

[type][type][type][data][data][data]

This is extremely counter-intuitive to me, having just spent the past  
few years tweaking QuickTime/mp4 atoms, which are...

[[size][type][data]] [[size][type][data]] [[size][type][data]]

Could someone give an example of a parsing algorithm to handle OSC  
arguments? It's not clicking on how you know when the type values end  
and the data values begin. This is simple I'm sure, but it's just not  
standing out at the moment.

thanks,

Jaime


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[Martin Peach]

The types are all one-byte values packed together. The type list ends with
at least one zero. After that the data is padded to 4-byte boundaries.
So you look for the comma that starts the list of types (no comma = no
types) and then count characters until the first zero. That gives you the
number of data values. For each type you can prepare an appropriate
container for the data and then fill it later when you scan the data values,
which arrive in the exact same order as the types.
Martin


Jaime Magiera wrote:

>Reply-To: "Developer's list for the OpenSound Control (OSC)
>Protocol"<osc_dev@...>
>To: OSC_dev@...
>Subject: [OSC_dev] Parsing question
>Date: Mon, 17 Dec 2007 15:48:44 -0500
>
>Hey folks,
>
>I'm new to the list, but have been working with OSC for a couple years  
>now. I included the ability to navigate QuickTime VR movies with the  P5
>Virtual Reality Glove using OSC. It's pretty cool. You can control  QTVR
>over a network.
>
>I had been relying on third-party OSC frameworks to parse out the  data.
>However, now I'm attempting to build a full client/server  framework. One
>thing that I never noticed before about the format: The  argument types are
>consecutive, with the values aligned afterward.
>
>[type][type][type][data][data][data]
>
>This is extremely counter-intuitive to me, having just spent the past  few
>years tweaking QuickTime/mp4 atoms, which are...
>
>[[size][type][data]] [[size][type][data]] [[size][type][data]]
>
>Could someone give an example of a parsing algorithm to handle OSC  
>arguments? It's not clicking on how you know when the type values end  and
>the data values begin. This is simple I'm sure, but it's just not  standing
>out at the moment.
>
>thanks,
>
>Jaime
>
>
>_______________________________________________
>OSC_dev mailing list
>OSC_dev@...
>http://www.create.ucsb.edu/mailman/listinfo/osc_dev

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[Jaime Magiera]

On Dec 17, 2007, at 4:03 PM, Martin Peach wrote:

> The types are all one-byte values packed together. The type list  
> ends with at least one zero. After that the data is padded to 4-byte  
> boundaries.
> So you look for the comma that starts the list of types (no comma =  
> no types) and then count characters until the first zero. That gives  
> you the number of data values. For each type you can prepare an  
> appropriate container for the data and then fill it later when you  
> scan the data values, which arrive in the exact same order as the  
> types.

Ahhhh... now I see. Thank you very much. I'm currently moving my app  
from Java Client to Cocoa. Once some of that is complete, I'll send  
you folks a link to the beta so you can play around. Here's the old  
version...

http://www.thoughtconduit.net

thanks again,

Jaime

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