How to use the command 'arecord' (with examples)

arecord is a versatile command-line tool used to record audio through the ALSA (Advanced Linux Sound Architecture) soundcard driver. It provides various options to capture high-quality sound snippets and manipulate them, making it a robust choice for professionals and enthusiasts needing audio recording capabilities on Linux systems. This article will explore different use cases of arecord, illustrating how to effectively use the command for various audio recording tasks.

Record a snippet in “CD” quality (with examples)

Code:

arecord -vv --format=cd path/to/file.wav

Motivation:

Recording audio in “CD” quality ensures high fidelity, capturing sound at a sample rate of 44.1 kHz and a bit depth of 16 bits, which is the standard for audio CDs. This format is beneficial for users requiring a high-quality recording, such as music producers, podcasters, or anyone producing content that necessitates crystal-clear audio.

Explanation:

• arecord: Initiates the command to record audio.
• -vv: Enables the verbose mode, allowing the user to view a visual representation of the input signal levels on the terminal.
• --format=cd: Sets the format to “CD” quality, i.e., 16-bit little-endian, 44.1 kHz, stereo.
• path/to/file.wav: Specifies the path where the recorded audio will be saved in WAV format.

Example Output:

Upon executing the command, you should see a visual gauge of the recording levels in your terminal, indicating the intensity of the sound being captured until you stop the recording with Ctrl-C.

Record a snippet in “CD” quality, with a fixed duration of 10 seconds (with examples)

Code:

arecord -vv --format=cd --duration=10 path/to/file.wav

Motivation:

Using a fixed duration is particularly useful when you want to capture a specific length of audio without manually stopping the recording. This is ideal for automated test recordings, sampling sounds, or recording fixed-length messages or instructions. It facilitates consistency and precision in your recordings.

Explanation:

• arecord: Command to record audio.
• -vv: Activates verbose visualization of audio levels.
• --format=cd: Chooses the “CD” quality format.
• --duration=10: Limits the recording to a duration of 10 seconds.
• path/to/file.wav: Designates where the resulting WAV file will be stored.

Example Output:

A short burst of level meters will appear in your terminal for 10 seconds, after which the recording will automatically cease, saving the audio snippet.

Record a snippet and save it as an MP3 (with examples)

Code:

arecord -vv --format=cd --file-type raw | lame -r - path/to/file.mp3

Motivation:

Converting recordings to MP3 format on-the-fly is advantageous for reducing file size and enhancing compatibility with various devices and platforms. MP3 is a popular audio format known for its compression and quality balance. This is beneficial for situations where storage space is at a premium or when files need to be shared online with minimal bandwidth.

Explanation:

• arecord: The command used to record audio.
• -vv: Displays a visual indicator of sound levels during recording.
• --format=cd: Ensures the input is recorded in CD quality before conversion.
• --file-type raw: Treats the recording as raw audio data.
• |: Pipes the raw audio data directly into the next application.
• lame -r -: The lame command encodes audio into MP3 format, with -r indicating raw input, and - signifying data streaming from arecord.
• path/to/file.mp3: Sets the output destination for the MP3 file.

Example Output:

The terminal displays audio levels visually during recording. Upon completion, the output MP3 file appears at the specified location, containing the recorded audio.

List all sound cards and digital audio devices (with examples)

Code:

arecord --list-devices

Motivation:

Identifying and listing all available sound cards and digital audio devices is crucial for configuring your system’s audio recording setup. It helps you determine the correct device to select in scenarios where multiple audio interfaces exist, ensuring the use of the desired input. This enhances efficiency in environments with complex audio configurations.

Explanation:

• arecord: Command to engage audio functionalities.
• --list-devices: Instructs arecord to enumerate all detected audio devices.

Example Output:

A detailed list of sound cards and digital devices appears in the terminal, complete with card numbers and device identifiers, allowing you to distinguish and select the appropriate recording device.

Allow interactive interface (with examples)

Code:

arecord --interactive

Motivation:

Interactive mode is helpful when user engagement is required during the recording process, such as adjusting settings, toggling playback, or pausing and resuming recordings without stopping the session. It is useful in live recording scenarios, audio testing, and workshops.

Explanation:

• arecord: Command to start recording.
• --interactive: Enables an interactive session, allowing real-time control over the recording process.

Example Output:

The terminal will accept space-bar or enter key inputs to control the audio stream, providing on-the-fly management while recording.

Test your microphone by recording a 5 second sample and playing it back (with examples)

Code:

arecord -d 5 test-mic.wav && aplay test-mic.wav && rm test-mic.wav

Motivation:

Testing your microphone setup ensures its functionality and recording quality, making it a critical step before starting any important session. This use case provides immediate feedback by playing back a test recording, verifying that the device captures sound as expected.

Explanation:

• arecord: Command to record audio.
• -d 5: Sets the recording duration to 5 seconds.
• test-mic.wav: Specifies the temporary file name for the audio clip.
• &&: Chains commands to execute sequentially when the preceding one completes successfully.
• aplay test-mic.wav: Plays back the audio file to check the recorded sound.
• rm test-mic.wav: Deletes the temporary file, tidying up after listening.

Example Output:

Upon executing the chain of commands, a 5-second recording will take place, instantly followed by playback of the recorded snippet, confirming audio capture. The file is then removed, maintaining a clean working environment.

Conclusion:

The arecord command provides an extensive toolkit for audio recording and manipulation through a Linux environment. Each use case elaborated here demonstrates its flexibility in handling various recording scenarios, achieving high-quality sound capture, managing audio formats, and more. By understanding these functionalities, users can optimize their audio recording practices to suit a wide range of professional and personal needs.