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Unbuffering Frame-Based Signals

The Buffers library contains two blocks that unbuffer frame-based sequences into sample-based sequences: Unbuffer and Partial Unbuffer.

The Unbuffer Block

The Unbuffer block lets you specify the block's initial output (Initial condition) and the number of channels in the input (number of columns in matrix).

The frame-based input to the block can be a single-channel signal (frame vector sequence) or a multichannel signal (frame matrix sequence). In both cases, the Unbuffer block converts the entire input frame to a sample-based output.

The sample period of the sample-based output, Tso, is related to the input frame period, Tfi, by the input frame size, Mi.

The Unbuffer block always preserves the signal's sample period (Tso = Tsi).

The figure below illustrates the unbuffering of a four-channel signal The Number of channels parameter is correspondingly set to 4. Each sample (row) of the input matrix is output separately. The input frame period and frame size are both 3, so the output sample period is 1.

The Unbuffer block delays inputs by one frame length (Tfi seconds); see "Initial State of Buffer Blocks" later in this section for more about the unbuffering delay.

The Partial Unbuffer Block

The Partial Unbuffer block unbuffers a selected portion of the input frame into a sample-based output. The First output index (M1) and the Last output index (M2) parameters determine the range of samples to be unbuffered from the input frame. For a multichannel input u, only rows u(M1:M2,:) are unbuffered to the output; all other input samples are discarded.

The output sample period is related to the input sample period by

where Mi is the input frame size. If the Last output index is greater than the length of the input frame (M2>Mi), or less than or equal to the First output index (M2M1), the block generates an error.


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