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This article introduces the relevant knowledge of "how to use Octave to deal with audio". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

Octave is a software similar to Matlab on Linux. It has a large number of functions and commands, supporting sound acquisition, recording, playback and digital processing of audio signals. It is used in entertainment applications, research, medicine and other scientific fields.

Signal superposition

Two signals S1 (t) and S2 (t) are added together to form a new signal R (t). The value of this signal at any moment is equal to the sum of the values of the two signals that make up it at that time. It looks like this:

R (t) = S1 (t) + S2 (t)

We will use Octave to recreate the sum of the two signals and see the effect through the chart. First, we generate two signals of different frequencies and take a look at what their superimposed signals look like.

The first step: generate signals of two different frequencies (oog file) > > sig1='cos440.ogg';% creating the audio file @ 440 Hz > > sig2='cos880.ogg';% creating the audio file @ 880 Hz > > fs=44100;% generating the parameters values (Period, sampling frequency and angular frequency) > > tcm 0lash FSV 0.02; > w1mm 2mm pirated 440ft; > w2=2*pi*880*t > > audiowrite (sig1,cos (w1), fs);% writing the function cos (w) on the files created > > audiowrite (sig2,cos (w2), fs)

Then we draw an image of the two signals.

Image of signal 1 (440 Hz)

> [Y1, fs] = audioread (sig1); > plot (y1)

Image of signal 2 (880 Hz)

> [y2, fs] = audioread (sig2) > > plot (y2) step 2: superimpose the two signals

Now let's show the sum of the two signals generated in the previous step.

> > sumres=y1+y2; > > plot (sumres)

The effect of superimposed signal image and signal image Octaver

In Octaver, the sound produced by this effect is unique because it simulates the low or high octave notes played by musicians (depending on the internal programming), and the simulated notes are paired with the original notes, that is, the two notes produce the same sound.

Step 3: add two real signals (such as two music songs)

To achieve this, we use two songs (sound sampling) from the Gregorian Chants.

Ode to Notre Dame (Avemaria Track)

First, let's take a look at the ode to Notre Dame and draw an image of it:

> > [y1jinfs] = audioread ('avemaria_.ogg'); > > plot (y1)

Song of Notre Dame

Hymns (Hymnus Track)

Now let's take a look at the hymn and draw its image.

> > [y2jinfs] = audioread ('hymnus.ogg'); > > plot (y2)

Hymns

Ode to Notre Dame + hymns

> audiowrite (y, y1+y2, fs); > [y, fs] = audioread ('avehymnus.ogg'); > > plot (y)

Song of Notre Dame + hymn

As a result, from an audio point of view, the two sound signals are mixed.

The product of two signals

For finding the product of two signals, we can use a method similar to summation. We use the same file we generated earlier.

R (t) = S1 (t) * S2 (t) > > sig1='cos440.ogg';% creating the audio file @ 440 Hz > > sig2='cos880.ogg';% creating the audio file @ 880 Hz > > product='prod.ogg';% creating the audio file for product > > fs=44100;% generating the parameters values (Period, sampling frequency and angular frequency) > > t=0:1/fs:0.02 > w1 / 2 pivoting 440 tons; > > w2 / 2 pirates 880 tons; > audiowrite (sig1, cos (w1), fs);% writing the function cos (w) on the files created > > audiowrite (sig2, cos (w2), fs); > > [y1jinfs] = audioread (sig1); > > [y2jinfs] = audioread (sig2); > audiowrite (product, y1.*y2, fs);% performing the product > > [yprod,fs] = audioread (product); > plot (yprod);% plotting the product%

Note: we must use the operator'. * 'because in the parameter file, this product is the value multiplied by the value. For more information, please refer to the Octave matrix operation product manual.

The product generates the image of the signal

The chart effect of multiplying two signals with very different basic frequencies (modulation principle) the first step:

Two sound signals with a frequency of 220 Hz are generated.

> > fs=44100; > fs=44100; > tcm plot 1 > FSV 0.03; > > wish2mm pivoting 220ft; > > plot (w); > > FSV (y1)

Carrier wave

Step 2:

Generate a 22000 Hz high frequency modulated signal.

> > y2=cos (100kw); > > plot (y2)

Debugging

Step 3:

Multiply two signals and draw an image

> > plot (y1.*y2)

Modulated signal

Multiply a signal by a scalar

The effect of multiplying a function by a scalar is tantamount to changing its range and, in some cases, the phase flag. Given a scalar K, a function F (t) multiplied by this scalar is defined as:

R (t) = Krabf (t) > > [yjourfs] = audioread ('cos440.ogg');% creating the work files > > res1='coslow.ogg'; > > res2='coshigh.ogg'; > > res3='cosinverted.ogg'; > > K1F0.2;% values of the scalars > > K2Cu0.5; > > K3Cube 1; > > audiowrite (res1, K1FY, fs) Product function-scalar > > audiowrite (res2, K2Secrety, fs); > audiowrite (res3, K3Secrety, fs)

Image of the original signal

> plot (y)

The image after the amplitude of the signal is reduced to 0.2 times that of the original signal.

> > plot (res1)

Low cosine

The image after the amplitude of the signal is reduced to 0.5 times the original amplitude.

> > plot (res2)

High cosine

Inverted signal image

> > plot (res3)

Inverted cosine

This is the end of the content of "how to handle Audio with Octave". Thank you for reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!

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