info

Get cumulative overrun and underrun

Syntax

S = info(asyncBuff)

Description

S = info(asyncBuff) returns a structure, S, containing the cumulative overrun and underrun information of the dsp.AsyncBuffer System object™, asyncBuff.

Examples

Read Variable Frame Sizes from Buffer

The dsp.AsyncBuffer System object™ supports reading variable frame sizes from the buffer.

Create a dsp.AsyncBuffer System object. The input is white Gaussian noise with a mean of 0, a standard deviation of 1, and a frame size of 512 samples. Write the input to the buffer using the write method.

asyncBuff = dsp.AsyncBuffer;
input = randn(512,1);
write(asyncBuff,input);
plot(input)
hold on

Store the data that is read from the buffer in outTotal.

Plot the input signal and data that is read from the buffer in the same plot. Read data from the buffer until all samples are read. In each iteration of the loop, randi determines the number of samples to read. Therefore, the signal is read in as a variable-size signal. The prevIndex variable keeps track of the previous index value that contains the data.

outTotal = zeros(size(input));
prevIndex = 0;
while asyncBuff.NumUnreadSamples ~= 0
    numToRead = randi([1,64]);
    out = read(asyncBuff,numToRead);
    outTotal(prevIndex+1:prevIndex+numToRead) = out;
    prevIndex = prevIndex+numToRead;
end
plot(outTotal,"r")
hold off

Verify that the input data and the data read from the buffer (excluding the underrun samples, if any) are the same. The cumulative number of overrun and underrun samples in the buffer is determined by the info function.

S = info(asyncBuff)

S = struct with fields:
     CumulativeOverrun: 0
    CumulativeUnderrun: 28

The CumulativeUnderrun field shows the number of samples underrun per channel. Underrun occurs if you attempt to read more samples than available.

Input Arguments

asyncBuff — Async buffer

dsp.AsyncBuffer System object

Async buffer, specified as a dsp.AsyncBuffer System object.

Output Arguments

S — Cumulative overrun and underrun information

structure

Cumulative overrun and underrun information, returned as a structure. The fields for S are described in the table.

Field	Value
CumulativeOverrun	Number of samples overrun per channel since last call to reset. The number of samples overrun is the number of unread samples overwritten.
CumulativeUnderrun	Number of samples underrun per channel since last call to reset. Underrun occurs if you attempt to read more samples than available.

The CumulativeOverrun and CumulativeUnderrun properties are data type int32.

Version History

Introduced in R2017a