How to record voice in uint8 format without telling the number of seconds in advance?

Hi,

I want to record voice and then have to do some processing on the recorded voice. The output samples of the recorded voice should be in uint8 format.

I have used wavrecord function as given below. It gives me uint8 samples but I have to tell the seconds of recording in advance.

y = wavrecord(recording_duration*Fs,Fs,'uint8');

I have also found another function called audiorecorder as given below. It helps me start a recording and stop a recording and I don't need to give the recording duration in advance but the output samples are not in uint8 format.

recorder = audiorecorder(Fs,nBits,nChannels)

Now, what I want is that:

1. I don't have to give recording duration in advance. 2. I should get the samples in uint8 format.

How can I achieve this?

Thank you.

Answer 1

[Daniel Shub]

doc getaudiodata

Will tell you

y = getaudiodata(recorder, dataType) converts the signal data to the specified data type: 'double', 'single', 'int16', 'int8', or 'uint8'

[Walter Roberson]

I believe Asad meant that the file must be written in uint8 format.

[Muhammad Asad]

I am not getting anything by using this command. Can you please explain how can I use this command. What my requirements are:

1. I don't have to give recording duration in advance.

2. I should get the samples in uint8 format.

[Daniel Shub]

@walter, I believe wavwrite automatically writes with the file with the same type as the input (if not, you can definitely specify the type to be written).

@Muhammad, you use getaudiodata with the audiorecoder object.

[Matlab Help Seeker]

@Daniel: Could you please tell me how to create an audiorecorder object. Can you please provide me a code that fulfills my two requirements?

Thank you.

Answer 2

[Walter Roberson]

Working from Daniel's answer:

recorder = audiorecorder(Fs,8,nChannels);

Then when ready,

record(recorder);

and when done,

stop(recorder);

Then to get the data as uint8,

samples = getaudiodata(recorder,'uint8');
clear recorder

[Daniel Shub]

It is not obvious to me what the audiorecorder function does with the nbits argument. While at first glance it makes sense to only record with 8 bit resolution if you want the result as an int8, but if audiorecorder or the soundcard does anything funky, you might be better off using

recorder = audiorecorder(Fs,16,nChannels);