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Buffering Delay and Initial Conditions. In both of the previous buffering examples the input signal is delayed by a certain number of samples. In "Example: Buffering Sample-Based Signals with Overlap" the delay is four samples. In "Example: Buffering Frame-Based Signals with Overlap" the delay is eight samples. The initial output samples adopt the value specified for the Initial condition parameter, which is zero in both examples above.
In fact, under most conditions the Buffer and Unbuffer blocks have some amount of latency. This latency depends on both the block parameter settings and the Simulink tasking mode. You can use the rebuffer_delay function to determine the length of the block's latency for any combination of frame size and overlap.
The syntax rebuffer_delay(f,n,m) returns the delay (in samples) introduced by the buffering and unbuffering blocks in multitasking operations, where f is the input frame size, n is the Buffer size parameter setting, and m is the Buffer overlap parameter setting.
For example, if you had run the frame-based example model in multitasking mode, you could compute the latency by entering the following command at the MATLAB command line:
This agrees with the block's output in that example. See Delay and Latency and the "Latency" section on each block reference page for more information.
| | Example: Buffering Frame-Based Signals with Overlap | Deconstructing Signals | |