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C Sync Wrapper

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Revision as of 19:13, 24 November 2010 by Brandyn (talk | contribs) (Interface)
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About

The freenect driver provides an "asynchronous" interface where you provide callbacks and it calls them when sensor data is available. There is another way of thinking about the data by having a "synchronous" interface where you call a function to get an image "freenect_get_depth" or "freenect_get_rgb" and it blocks and gives you back the data.

This is implemented by using a thread to handle the callbacks and a buffer to provide an interface for the client. You are guaranteed to get the buffers in order by timestamp (e.g., you won't get something older than your last). You may not get all frames with this interface (e.g., there may be gaps).

Who is involved

Search for Synchronous in People

However (Brandyn) and (amiller) are trying to organize things for the Synchronous interface.

Interface

   #define DEPTH_BYTES 614400 // 480 * 640 * 2                                                                                   
   #define RGB_BYTES 921600  // 480 * 640 * 3
                                                                               
   int freenect_get_rgb(char **rgb, uint32_t *timestamp);
   Synchronous rgb function, starts the runloop if it isn't running                                                          
                                                                                                                             
   Args:                                                                                                                     
       rgb: Populated with a pointer to a RGB buffer (of size RGB_BYTES)                                                     
       timestamp: Populated with a pointer to the associated timestamp                                                       
                                                                                                                             
   Returns:                                                                                                                  
       Nonzero on error.                                                                                                     
   int freenect_get_depth(char **depth, uint32_t *timestamp);
   Synchronous depth function, starts the runloop if it isn't running                                                        
                                                                                                                             
   Args:                                                                                                                     
       depth: Populated with a pointer to a depth buffer (of size DEPTH_BYTES)                                               
       timestamp: Populated with a pointer to the associated timestamp                                                       
                                                                                                                             
   Returns:                                                                                                                  
       Nonzero on error.