Using the 'afinfo' Command in macOS (with examples)

The ‘afinfo’ command is a built-in utility in macOS that provides information about audio files. It acts as an audio file metadata parser, revealing detailed information about audio files’ properties. This tool is particularly handy for audio engineers, software developers, or enthusiasts who need to inspect audio file information and metadata without opening a graphical application.

Use Case 1: Display info of a given audio file

Code:

afinfo path/to/file

Motivation: Understanding a comprehensive profile of an audio file is vital when assessing quality, format compatibility, or any required adjustments or processing. This command provides a full range of details including file type, duration, bit rate, sample rate, and channel count.

Explanation:

• afinfo: The command itself, used to invoke the audio file information utility.
• path/to/file: This is a placeholder for the actual path and name of the audio file whose information you want to retrieve.

Example Output:

File:           path/to/file
File type ID:   AIFF
Num Tracks:     1
----
Track 0:
Format:         2 ch,  44100 Hz, 'lpcm' (0x000000BE) 16-bit little-endian signed integer
Duration:       0:05.345
Channel Layout: Stereo (L R)

Use Case 2: Print a one line description of the audio file

Code:

afinfo --brief path/to/file

Motivation: Sometimes, the user may need a quick overview or summary of an audio file, perhaps to validate its format or confirm it is as expected without delving into details. This command provides a succinct overview.

Explanation:

• afinfo: The command used to gather audio file info.
• --brief: A flag that tells afinfo to return only a one-line description, which typically includes file type and its basic attributes.
• path/to/file: The path to the audio file being queried for its summary.

Example Output:

AIFF, Stereo, 44100 Hz, 16-bit, 5.345 seconds

Use Case 3: Print metadata info and contents of the audio file’s InfoDictionary

Code:

afinfo --info path/to/file

Motivation: Detailed metadata can include crucial information, such as copyrights, artist names, or notes, which are often stored within a file’s InfoDictionary. This command unveils that detailed metadata, which might not be visible when playing the file normally.

Explanation:

• afinfo: The audio info command.
• --info: This option requests additional metadata found in the file’s InfoDictionary.
• path/to/file: The audio file whose metadata is needed.

Example Output:

File: path/to/file
...
InfoDictionary:
    Approximate duration in milliseconds: 5345
    Artist: Example Artist
    Title: Example Song
...

Use Case 4: Print output in XML format

Code:

afinfo --xml path/to/file

Motivation: XML output can be beneficial for users who want to integrate audio file information into other software systems or for further processing. XML is both human and machine-readable, making it ideal for automated processing.

Explanation:

• afinfo: Calls the metadata parser.
• --xml: Converts the output to XML format, a structured format that is widely used in data interchange between systems.
• path/to/file: Path to the target audio file.

Example Output:

<?xml version="1.0" encoding="UTF-8"?>
<audiofileinfo>
    <file>path/to/file</file>
    <filetype>AIFF</filetype>
    <numtracks>1</numtracks>
    <track>
        <format>2 ch, 44100 Hz, 'lpcm'</format>
        <duration>5345 ms</duration>
    </track>
    <metadata>
        <artist>Example Artist</artist>
        <title>Example Song</title>
    </metadata>
</audiofileinfo>

Use Case 5: Print warnings for the audio file if any

Code:

afinfo --warnings path/to/file

Motivation: Warnings can alert users to potential issues with an audio file, such as corruption, compatibility problems, or missing metadata. This command allows users to preemptively address any warnings to ensure smooth playback or processing.

Explanation:

• afinfo: Initiates the audio file inspection.
• --warnings: Flags the command to specifically check for and return any warnings related to the audio file.
• path/to/file: The file being inspected for warnings.

Example Output:

File: path/to/file
Warning: Detected non-standard bit rate

Use Case 6: Display help

Code:

afinfo --help

Motivation: Users unfamiliar with the command or its options can quickly access the available options and understand their functionality through the help command. This is useful for learning and troubleshooting.

Explanation:

• afinfo: The command that provides file information.
• --help: A standardized flag that outputs the command’s help information, detailing available options and their descriptions.

Example Output:

Usage: afinfo [option] path/to/file
Options:
    --brief     Print brief information
    --info      Print detailed metadata info
    --xml       Print output as XML
    --warnings  Print file warnings
    --help      Display this help

Conclusion:

The afinfo command is a valuable tool for accessing and inspecting audio file metadata on macOS. This article has illustrated various ways it can be utilized - from extracting concise information to analyzing detailed metadata and handling warnings. Each use case aligns with different user needs, whether for quick checks, in-depth analysis, or system integration. Understanding how to harness afinfo equips users with greater control and insight over their audio files.