AudioMetadata Class Reference

Extracts musical metadata from audio files. More...

#include <gin_audiometadata.h>

Public Member Functions
	AudioMetadata (const juce::File &f, juce::AudioFormatManager &mgr)
	Creates an AudioMetadata object by reading metadata from an audio file.

Public Attributes
std::optional< int >	root
	The root note (MIDI note number 0-127).
std::optional< float >	bpm
	The tempo in beats per minute.
std::optional< int >	numerator
	Time signature numerator (beats per bar).
std::optional< int >	denominator
	Time signature denominator (beat unit).
std::optional< int64_t >	loopStart
	Loop start point in samples.
std::optional< int64_t >	loopEnd
	Loop end point in samples (exclusive).

Detailed Description

Extracts musical metadata from audio files.

AudioMetadata reads loop, tempo, time signature, and root note information from WAV and AIFF files. It supports:

• WAV files: ACID chunk (root note, BPM, time signature) and sampler chunk (loop points, root note via MidiUnityNote)
• AIFF files: Apple Loops basc chunk (root note, BPM, time signature) and INST chunk loop points via cue markers

For files without embedded metadata, the class attempts to deduce:

• Root note from the filename (e.g., "bass_C#.wav" -> C#)
• BPM from the filename (e.g., "loop_120bpm.wav" -> 120) or cue labels

All metadata fields are optional and will only be set if the corresponding data is found in the file or can be deduced.

Usage:

juce::AudioFormatManager formatManager;
formatManager.registerBasicFormats();
 
AudioMetadata metadata (myAudioFile, formatManager);
 
if (metadata.bpm.has_value())
    DBG ("BPM: " << *metadata.bpm);
 
if (metadata.loopStart.has_value() && metadata.loopEnd.has_value())
    DBG ("Loop: " << *metadata.loopStart << " to " << *metadata.loopEnd);

See also

juce::AudioFormatReader, juce::WavAudioFormat, juce::AiffAudioFormat

Constructor & Destructor Documentation

AudioMetadata()

AudioMetadata::AudioMetadata	(	const juce::File &	f,
		juce::AudioFormatManager &	mgr
	)

Creates an AudioMetadata object by reading metadata from an audio file.

Parameters

f	The audio file to read metadata from
mgr	An AudioFormatManager with registered formats (call registerBasicFormats() first)

Member Data Documentation

root

std::optional<int> AudioMetadata::root

The root note (MIDI note number 0-127).

Read from ACID chunk (WAV), sampler chunk MidiUnityNote (WAV), Apple Loops basc chunk (AIFF), or deduced from filename.

bpm

std::optional<float> AudioMetadata::bpm

The tempo in beats per minute.

Calculated from ACID chunk beat count (WAV) or Apple Loops beat count (AIFF), or deduced from filename/cue labels.

numerator

std::optional<int> AudioMetadata::numerator

Time signature numerator (beats per bar).

For example, 4 in a 4/4 time signature. Read from ACID chunk (WAV) or Apple Loops basc chunk (AIFF).

denominator

std::optional<int> AudioMetadata::denominator

Time signature denominator (beat unit).

For example, 4 in a 4/4 time signature. Read from ACID chunk (WAV) or Apple Loops basc chunk (AIFF).

loopStart

std::optional<int64_t> AudioMetadata::loopStart

Loop start point in samples.

Read from WAV sampler chunk (Loop0Start) or AIFF INST chunk via cue point markers.

loopEnd

std::optional<int64_t> AudioMetadata::loopEnd

Loop end point in samples (exclusive).

Read from WAV sampler chunk (Loop0End + 1) or AIFF INST chunk via cue point markers. Only set if within file length.

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The documentation for this class was generated from the following file:

• gin_audiometadata.h