Basics of Audio and Video Editing Class 12 Notes are designed to help students understand fundamental concepts such as audio and video formats, editing tools, timelines, transitions, effects, and exporting media files. These notes follow the Class 12 curriculum and present topics in a simple and structured manner, making them useful for exam preparation as well as practical learning.
Basics of Audio and Video Editing Class 12 Notes
There are various audio editing software that provide different types of functionalities and support various operations. Some of the examples of the free and open-source audio editing software are Audacity, Traverso DAW, Ardour, Mixxx, Qtractor and various other commercial software.
Introduction about Audacity
Audacity is one of the best audio editing software. Audacity Free and Open-Source Software, the source code of the software is available to all. Roger B. Dannenberg, Professor of Computer Science, started the research project Audacity, along with his graduate student Dominic Mazzoni.
Features of Audacity
Audacity allows you to record, export and import various sound file formats, and it has multiple plug-ins which enable us to extend the functionality of Audacity.
Applications of audio editing skills
- Audio/radio advertisement
- Documentary films need audio editing to synchronise with the video.
- Creating Podcasts
- Recording speeches
- Creating sound stories
- Record sound for slide presentations
- Editing or compiling songs together
Activities in audio editing
- Remove unwanted sounds like breaths, coughs, ringing of the phone, etc.
- Remove repeated dialogues.
- Add music to the beginning or at the end of video clips.
- Stretch/shorten audio and sound effects according to the length of the visual.
- Slice together audio recorded at different sittings.
- Sync up different musical instruments so that they all can sound on the beat.
- Loop, slice and edit beats.
Tips for recording good-quality audio
- Use a good-quality external microphone for clear sound.
- Keep the microphone steady and fixed in one position.
- Record 10 seconds of silence at the start to capture ambient noise for later removal.
- Always check audio with headphones (or studio monitors for professional work).
- Aim for minimum or zero ambient noise during recording.
Import Audio Files into Audacity
Launch Audacity > go to File > Import > Audio (shortcut: Ctrl + Shift + I).
Export audio clips to various formats.
Audacity allows us to export your edited work into various following formats: AIFF, WAV 16 and 32 bit, MP3 files, Ogg files, etc.
- Preset (Developer Recommended)
- Insane: Best quality, constant bit rate of 320 kbps (~2.4 MB/min).
- Extreme: Extremely high quality.
- Standard: Very good quality encoding.
- Medium: Good quality, suitable for casual listening/portable devices.
- Variable (VBR)
- Bit rate varies with sound complexity.
- Maintains consistent audio quality.
- Constant (CBR)
- Fixed bit rate throughout.
- Predictable file size, but least consistent quality.
- Average (ABR)
- Sets a known average bit rate.
- Allows some fluctuation depending on encoding difficulty.
Quality
This list allows us to select the bit rate in kbps (kilobits per second) for encoding your file. A higher bit rate always gives better quality but at the expense of a larger file size and vice versa.
Variable Speed, Choice of speed is available when using variable bit rate encoding. It determines the speed and bit allocation routines of the encoding algorithm.
Channel Mode
These controls determine how two channels of a stereo MP3 are encoded, or if exported, the MP3 should always be mono. In stereophonic sound more channels are used (typically two). We can use two different channels and make one channel feed one speaker and the second channel feed a second speaker (which is the most common stereo setup). This is used to create directionality, perspective and space.
Editing an Existing Audio File
- Prepare the audio file.
- Launch Audacity > File > Import > Audio.
- Waveforms appear in the main window:
- The top half = left channel
- Bottom half = Right channel
- Play and listen to the imported audio.
Removing noise from the audio recording
- Select the “silent” section of our audio, where it’s just a noise.
- Go to the Effects menu and click Noise Removal.
- Click Get Noise Profile.
- Select all of the audio from which we want that background noise to be removed.
- Go to the Effects menu and click Noise Removal.
- Adjust the settings if necessary (defaults are fine) and click OK.
- Listen to ensure our audio doesn’t sound like it’s underwater.
Effects, Generators and Analysers
- An effect changes the audio in some way, like an artificially created or enhanced sound.
- A generator creates new audio, either in an existing track or in a new track.
- An Analyse tool performs analysis on a selection of audio – it does not change the audio and does not create new audio.
Some of the useful effects which we can use are as follows:
- Amplify: Increase/decrease the volume of selected audio.
- Normalise: Set max amplitude, balance stereo channels, and remove DC offset.
- Fade In: Smoothly increase volume at the start.
- Fade Out: Smoothly decrease volume at the end.
- Bass & Treble: Adjust low (bass) and high (treble) frequencies independently.
- Equalisation: Fine-tune volume levels of specific frequencies.
- Noise Reduction: Reduce constant background noise (fans, hums, tape hiss).
- Change Pitch: Alter pitch without changing tempo.
- Change Speed: Altering speed also changes pitch.
- Echo: Add delayed reflection of sound for echo effect.
Video Editing
Video editing is the process of manipulating raw videos, clips, images, and sounds to create a new movie or new video.
Video editing includes the following activities:
- Rearranging, adding and removing sections of video clips or audio clips.
- Applying colour correction, filters and other enhancements.
- Creating transitions between clips.
- Removing unwanted footage or parts of the video, or selecting the best shot.
- Creating flow in the story with a sequence of the video shots and music and narration.
- Add effects, graphics, music, etc.
- Change the style or pace or add effects to the video.
- Adding titles in the video.
Different Types of Video Editing
There are three types of video editing techniques, as follows.
- Linear Editing: This is an old technique, and now it is not being used. This technique uses several videotapes in sequence, and a single new video will be created.
- Non-Linear: In this technique, all the videos are arranged in a timeline using computer software. Non-linear editing is also called non-destructive editing. It is a form of audio, video and image editing in which the original content is not modified in the course of editing.
- Live Editing: Multiple camera inputs are given to the mixer, and then the live coverage of an event, like sports broadcasts, is provided here; editing happens in real time.
Video Editing Basics
- Video Import: Refers to the loading of a video captured from a digital camera to the computer.
- Video footage: It’s a raw material of video imported from the camera on which the video editor will work.
- Stock Footage: It is also referred to as archive footage, library pictures and file footage and is used as template files.
- Cut: It is an instant change from one shot to another. For example, we are watching one scene and immediately switched to another scene.
- Jump Cut / Cut-in: It is a cut between the shots where the angle and position are the same.
- Cutaway: Within a sequence of scenes we put another shot; a cutaway is used to show parallel actions.
- Video Frame: A frame is made up of the complete image; let’s say for a film we have 24 frames per second. frame rate is the frequency at which consecutive images called ‘frames’ appear on a display.
- Transition: It is a change from one shot to another. We can use transitions like dissolve, where first shot gradually disappear and next become more visible.
Video Recording Principles
- 180-Degree Rule: Keep the camera on one side of the 180° line between subject and camera. Crossing the line changes object position → confuses audience. Use multiple cameras on the same side to avoid breaking the rule.
- Sequence Editing: Arrange videos in a logical sequence during editing. Maintain continuity in direction, movement, position, and audio. A proper sequence gives meaning and flow to the video.
Pudovkin’s five principles of editing
Pudovkin’s techniques can be used in video editing to enhance the viewer’s understanding of a story and to create a specific reaction from the audience.
- Contrast: It is the cutting between two different scenarios to highlight the difference between them.
- Parallelism: In this we can connect two seemingly unrelated scenes by cutting between them and focusing on parallel features.
- Symbolism: In symbolism we move from our main scene to something which creates a symbolic connection for the audience.
- Simultaneity: It is the cutting between two simultaneous events as a way of driving up the suspense.
- Leitmotif: The ‘reiteration of the theme’ involves repeating a shot or a sequence at crucial moments as a sort of code.
Video Editing with Kdenlive
Kdenlive (KDE Non-Linear Video Editor) is free and open-source video editing software. Jason Wood started the Kdenlive project in 2002.
Features of Kdenlive:
- Free and open-source video editor, uses Qt and the KDE Frameworks libraries.
- Multi-track video editing to use and arrange several audio and video tracks.
- Multiple audio/video formats: almost all formats are supported.
- Highly configurable interface to fit your workflow.
- Titles for the videos can be created with the inbuilt title editor.
- Quickly create slideshows from pictures or images using various transitions.
- Lots of effects and transitions.
Kdenlive User Interface
- Project Bin: This is called the project bin; here we can import all your audios, videos, images and titles which we want to include in the project.
- Properties Windows: This window displays the properties’ effects and transitions, which you can change and properties of the selected file from the timeline or project bin
- Transition and Effects: Using it, we can choose the transitions and various effects for the videos.
- Video preview window: Here the preview of the video will be shown.
- Timeline: This is the most significant part of the user interface; here you will keep all your videos. audios and pictures. It is also a chronological display of an edited sequence in a non-linear editing system.
Slideshow Clip Activity
Steps to create a slideshow:
- Step 1: Be ready with pictures for your slide show.
- Step 2: We will also need suitable background audio for our slide show.
- Step 3: Create a new project, and from the project bin window, click the little arrow to add the slideshow clip as shown in the figure below, then from the same arrow of the bin, select the Add clip option.
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