concatenate audio files in simulink

How can I concatenate 2 or more audio (.wav) sounds into one?

Answer 1

[jibrahim]

Hi Katarina,

Use two 'From Multimedia File' blocks to read the wav files.

https://www.mathworks.com/help/dsp/ref/frommultimediafile.html

There are multiple ways of concatenating two signals in simulink.For example:

https://www.mathworks.com/help/simulink/slref/vectorconcatenate.html

[Katarina Vuckovic]

I tried you suggestion. However, when I use the concatinate block, I get the two sounds playing at the same time. Instead, I want them to play one after the other. For example, the first audio plays "My name is" and the second plays "Mike", such that when you combine them the output is "my name is Mike".

[Walter Roberson]

Make sure you concatenate along the correct dimension.

Audio files show up as 2D arrays in which each column is an audio channel. In the case that you have two audio files each of which has one channel, then if you concatenate along the second dimension (equivalent of horzcat()) then you would end up with a 2D array with two channels, giving the effect of playing one of the files on the left channel and the other on the right channel.

[Katarina Vuckovic]

Is there a way to detect the end of one audio and use it as a trigger to intiate the next ?

[Walter Roberson]

Output end-of-file indicator

Use this check box to determine whether the output is the last video frame or audio sample in the multimedia file. When you select this check box, a Boolean output port labeled EOF appears on the block. The output from the EOF port defaults to 1 when the last video frame or audio sample is output from the block. Otherwise, the output from the EOF port defaults to 0.

[Katarina Vuckovic]

Right now I am able to get it to work by triggering the two audio files to be on/off using a constant pulse. This works only if the messages are constant duration. However if the messagase are of variable duratio, I don't know how to detect that the first message has ended.

Answer 2

[Katarina Vuckovic]

Hi Walter, if I play one on the left channel and one on the right, wouldn't they still be playing at the same time instead of one after the other?

[Walter Roberson]

Yes. My explanation was for how it happened that they were playing at the same time. The cure is to ensure that you concatenate on the first dimension instead of the second.