Video and Audio Editing - Audio Editing Processes

Objective

Perform audio editing processes (normalizing, trimming, compression)

1. Audio Normalization

Audio normalization is the process of adjusting the audio level to a target loudness. This ensures that the audio is consistently loud enough without clipping (distorting due to exceeding the maximum level).

Normalization typically involves raising or lowering the overall volume of the audio.

There are two main types of normalization:

• Peak Normalization: Adjusts the audio level so that the loudest peak in the audio reaches a specified target level (e.g., -1dBFS).
• RMS Normalization: Adjusts the audio level based on the Root Mean Square (RMS) value, which represents the average loudness of the audio.

Formula (Peak Normalization):

$$ \text{Target Loudness} = \text{Original Loudness} + \text{Adjustment} $$

The 'Adjustment' value is calculated to bring the peak of the audio to the target loudness.

2. Audio Trimming

Audio trimming involves removing unwanted sections from the beginning, end, or middle of an audio file.

This is a fundamental editing process used to remove silences, mistakes, or irrelevant parts of the audio.

Trimming can be done using tools that allow precise selection of the start and end points of the desired audio segment.

Tools used for trimming:

• Selection tools
• Precise cutting tools
• Markers to define start and end points

3. Audio Compression

Audio compression is the process of reducing the file size of an audio file. This is achieved by removing redundant or less important data from the audio signal.

Compression can be lossy or lossless:

• Lossy Compression: Reduces file size significantly by discarding some audio data that is considered less perceptible to the human ear. Examples include MP3 and AAC.
• Lossless Compression: Reduces file size without discarding any audio data. The original audio can be perfectly reconstructed from the compressed file. Examples include FLAC and ALAC.

Bitrate is a key factor in audio compression. A higher bitrate generally results in better audio quality but a larger file size. A lower bitrate results in a smaller file size but potentially lower audio quality.

Table summarizing audio compression formats:

Format	Compression Type	File Size	Audio Quality	Common Uses
MP3	Lossy	Small	Moderate	General music listening, streaming
AAC	Lossy	Small to Moderate	Good	Apple devices, streaming
FLAC	Lossless	Large	Excellent	Archiving, high-fidelity listening
ALAC	Lossless	Large	Excellent	Apple devices, archiving

Further Considerations

When performing audio editing, it's important to consider the context of the audio and the intended use of the final product. Over-processing can negatively impact audio quality.