Audio and video editing with Screencast-o-matic and Audacity.

When you want to show a tool or process, most professionals use video tutorials from specialized pages, which is why those who dedicate themselves to generating multimedia content must take into account factors that could affect resources during their creation. , such as audio. This article will show some tools to edit audio and video after its creation, these will allow to eliminate, insert images or reduce sounds that could hinder the clarity of the video tutorial.

It must be taken into consideration that depending on the speaker's speech, the environment where it is recorded, and the resources such as microphones (including its position, speaker's distance or friction), there will be different types of sounds, such as: breaths light or strong, external sounds such as wind, rain, steps, manipulation of tools (mouse click or typing), if you have a script of the video on paper you could also hear the sound of the leaves, among many others that later make it difficult the multimedia resource is pleasing to the listener and can easily be understood.

It is for the aforementioned that a tutorial is presented on how to export, edit and import audio after having recorded the sound, and how to add a presentation image and titles, in a video after finishing the recording.

Input data

Initially, a video tutorial that has previously been made with its included audio is chosen, for this example we will use one in .mp4 format. As software for editing will be used screencast-o-matic for video and Audacity for the audio. Likewise, as a better presentation, an image that indicates what the tutorial is about will be inserted at the beginning of the video.

We have been asked, about a video tutorial of a buffer routine using ArcGIS PRo, to which we must make the following adaptations:

  • Change the canvas size to 1280 x 720.
  • Superimpose an image and text at the beginning and end of the video.
  • Edit audio, cleaning background noise and unplanned sounds.

Sequence of steps

The sequence of steps that we indicate is somewhat summarized, but in the video that is presented at the end it can be seen in more detail. Before starting the process, the aforementioned programs must be installed on the computer, screencast-o-matic y Audacity,

1 Video edition

  • Step 1. Open the video: It starts loading the video on the platform screencast-o-matic, when opening it will show the option to edit where the audio will be extracted that will later be modified and also the tools are placed to place the presentation image of the videotutorial. We do not detail more about what screencast-o-matic does because we did it before an an article before.

  • Step 2. Superimpose image to video: When you open the edit option, a new window is displayed, where the tools are located, to enter the presentation image to the video, you must choose the overlay image option, search the corresponding file and stretch or contract, according to the time that you have to present the video.

  • Step 3. Overlay text to video: Then the corresponding title is placed, in the superimpose tool text is chosen and the parameters are placed in terms of typography, color and size, and when it is ready, the changes are accepted.

  • Step 4. Copy overlays to another part of the video: both superimpositions are copied, both the start image and the title, are placed at the end of the video in order to complete the tutorial, the end is placed on the video map and the copied elements are pasted.

Audio Editing

For audio editing we use the Audacity program, which is free and open source, you can record, edit, import and export audio. It has functions such as digitizing any type of sound coming from sources such as cassettes or vinyl records. It is available for Windows, Mac OsX, and Ubuntu, it is not necessary to install the program because it also has a portable version.

  • Step 1. Export the audio in .wav format: When you enter in the edit option of screencast-o-matic, there is a panel where the music or audio that contains the video is located, this audio will be extracted and exported in .wav format to be able to edit the program Audacity,
  • Step 2. Open the audio in Audacity: After having extracted the audio, it opens in the program Audacity, with the option File - Open, when loading in the system you can see the audio map that has been exported from screencast. In this program you can load multiple tracks. It is important to listen to the entire file to determine which parts should be muted or cut, it must be taken into account that if a part of the audio is cut it will not coincide with the video time, it is advisable if there is any error using the mute tool so that the extension of the audio continues to coincide with the video.

If when opening the audio in the program is not heard, it is because the microphone must be configured, the edit - preferences - devices - playback menu is located in the main panel. There you have to select the hearing aid that we are really using.

  • Step 3. Noise reduction: For noise reduction, a silence segment is selected, to capture the noise to be chosen; this is done in the effects menu, noise reduction. Then the entire audio file is selected by pressing CTRL + A, or in the main menu you will find the selection tool where the option is chosen, then in the effect menu the noise reduction tool is located. Later a window is opened where the parameters are specified, for this case they are kept by default and you choose to accept to run the process. Another window will appear indicating when the noise reduction started and the estimated time that this action would end.

In the effect menu, a large number of tools to be applied in the audio are located if necessary, it is possible to eliminate clicks of the mouse, normalize the audio, highlight bass, level, reverse, repeat, compress or change the rhythm.

  • Step 4. Clean unplanned sounds: After the reduction of sound, it is determined that parts of the audio contain unexpected noises or some kind of error, with the cursor all the space corresponding to the noise is selected (4), and for a greater precision in the selection the buttons of the zoom (+) and (-). That allow you to expand or decrease the audio map and easily locate the noise to be eliminated.
  • Cut button: with this button you get only the fragment selected by the cursor, that is, it extracts only one space from the audio. If it is required to cut a part of the audio, without modifying or eliminating the rest, the scissors tool is used.
  • Mute button: this button selects annoying noises and removes all traces.
  • Zoom in and out: helps to better visualize the sound map.

Of course, as you have seen AudaCity allows to make more noise cleaning and tone balance, to achieve a very good quality audio. In this video, it focuses on reducing ambient noise and cleaning unplanned sounds in moments of silence.

As you have seen, we have not used the option to cut audio, but to silence the unplanned noise, because we take care that the file maintains the length of time so as not to lose synchronicity with the video. If it were only audio, we would surely cut it to reduce unnecessary silences, to which a video or images synchronized with the final audio will be added.

These functions allow easy manipulation of one or more tracks, you can undo any change if a cut or silence is applied during editing, it also has keyboard shortcuts. If necessary, with this program you can add sound effects to improve the audio, such as echo, inversion or tone.

  • Step 5. Export the audio edited in Audacity: Once the complete edition of the audio file has been made, it is exported to .wav format, (however there are other options such as .mp3, -aiff, .ogg or .au) in the file menu - export as .wav, this step is done to enter it again in the video through screencast-o-matic,

  • Step 6. Change canvas size of video: After having finished the audio and video editing process, we proceed to save the file, taking into account that for a better visualization the size of the video canvas must be 1280 x 720, if the video does not correspond to this size, can be changed in the canvas option, by choosing 720p HD. The program allows either adding black backgrounds to the size not covered by the original video, or stretching the existing one to fit even if you lose a segment because the video did not have the same proportion.
  • When it is considered ready, the button is pressed Done for finalize the name, format, if the cursor is displayed, the location where the video is exported and finally choose the quality of the recording output between low, normal or high, finally the video is published.

Both programs offer the user the convenience of editing, their tools are easy to learn to perform this type of process, especially for those who are part of the 2.0 classrooms and use this resource as a teaching medium.

The video shown is a summary. If you want access to the full video, request it by mail or whatsapp that is in the header of this site.

One Reply to “Audio and video editing with Screencast-o-matic and Audacity.”

  1. You explain fatally, you don't understand anything to do…

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