Latency is the delay, measured in samples or frames, between the
input and the output of the block.
The Downsample block has zero-tasking latency in the
following cases:
The Downsample factor parameter,
K, is 1
.
The Input processing parameter is set to
Columns as channels (frame based)
, and the
Rate options parameter is set to
Enforce single-rate processing
.
The Input processing parameter is set to
Columns as channels (frame based)
, the
Rate options parameter is set to Allow
multirate processing
, the Sample
offset parameter, D, is set to
0
, and the input frame size is equal to 1.
The Input processing parameter is set to
Elements as channels (sample based)
, and the
Sample offset parameter, D, is
0
.
Zero-tasking latency means that the block propagates input sample
D+1 (received at t = 0) as the first
output sample, followed by input sample D+1+K,
input sample D+1+2K, and so on. When there is
zero-tasking latency, the block ignores the value of the Initial
conditions parameter.
In all other cases, the latency is nonzero:
When the Input processing parameter is set to
Elements as channels (sample based)
, the
latency is one sample.
When the Input processing parameter is set to
Columns as channels (frame based)
and the
input frame size is greater than one, the latency is one frame.
In all cases of one-sample latency, the initial condition for
each channel appears as the first output sample. Input sample D+1
appears as the second output sample for each channel, followed by input sample
D+1+K, input sample
D+1+2K, and so on. The Initial
conditions parameter can be an array of the same size as the input or
a scalar to be applied to all signal channels.
In all cases of one-frame latency, the
Mi rows of the initial condition
matrix appear in sequence as the first Mi
output rows. Input sample D+1 (row D+1 of the
input matrix) appears in the output as sample
Mi+1, followed by input sample
D+1+K, input sample
D+1+2K, and so on. The Initial
conditions value can be an
Mi-by-N matrix
containing one value for each channel or a scalar to be repeated across all elements
of the Mi-by-N
matrix.