How to Read Audio File Metadata
Audio files contain hidden metadata in their binary headers that describes the recording's technical properties and, in many cases, its content information. WAV files store metadata in their RIFF header — sample rate, channel count, bit depth, and data size. MP3 files use ID3 tags to store human-readable information like title, artist, album, year, and genre.
This tool reads both types of metadata directly in your browser. Upload your audio files and the tool parses each file's binary header using JavaScript's DataView API. For WAV files, it reads the RIFF/WAVE header structure to extract sample rate (44100 Hz, 48000 Hz, etc.), channel count (mono or stereo), bit depth (16-bit, 24-bit, 32-bit float), and calculates the approximate duration from the data size and byte rate.
For MP3 files, the tool reads the ID3v1 tag — a 128-byte block located at the very end of the file. This tag contains fixed-length fields for title (30 bytes), artist (30 bytes), album (30 bytes), year (4 bytes), comment (28 bytes), and genre (1 byte as an index into a standard genre list). While ID3v1 has character length limitations, it remains the most universally supported MP3 metadata format.
The batch rename feature lets you use metadata values as filename components. Define a pattern using variables like {artist} - {title} and the tool generates new filenames based on each file's embedded tags. This is invaluable for organizing music libraries where files have inconsistent or missing filenames but correct ID3 tags.
Understanding Audio File Formats
WAV (Waveform Audio File Format): The standard uncompressed audio format. WAV files contain raw PCM audio data wrapped in a RIFF container. A typical WAV file at CD quality (44.1 kHz, 16-bit, stereo) uses about 10 MB per minute. WAV is preferred for audio production because it preserves every sample without compression artifacts.
MP3 (MPEG Audio Layer III): The most widely supported lossy compression format. MP3 reduces file size by 75-90% compared to WAV by removing audio information that humans are less likely to perceive. Bit rates range from 96 kbps (low quality) to 320 kbps (near-transparent quality). MP3 files support ID3 tags for metadata.
FLAC (Free Lossless Audio Codec): A lossless compression format that reduces file size by 30-50% compared to WAV without any quality loss. FLAC is popular among audiophiles and music archivists who want smaller files without accepting compression artifacts.
OGG Vorbis: An open-source lossy format that often achieves better quality than MP3 at the same bit rate. OGG is used by Spotify for streaming and by many game engines for in-game audio.
AAC (Advanced Audio Coding): The default format for Apple devices and iTunes. AAC achieves better quality than MP3 at the same bit rate and is used by YouTube, Apple Music, and Nintendo Switch.
Why Audio Metadata Matters for Organization
A music library without consistent metadata is effectively unsearchable. When files are named "track01.mp3" or "Unknown Artist - Unknown Title.mp3," you cannot find specific songs, sort by artist, or create playlists based on genre or year. Proper metadata transforms a folder of random files into a structured, searchable library.
For podcasters, consistent metadata ensures that episodes display correctly in podcast apps with the right title, episode number, and publication date. For musicians distributing their work, accurate ID3 tags ensure that listeners see the correct artist name and track title in their music player. For audio engineers, knowing the sample rate and bit depth of source files is essential for mixing and mastering workflows.
The batch rename feature addresses a common problem: files that have correct metadata but wrong or inconsistent filenames. By renaming files using a pattern like {artist} - {album} - {track} - {title}, you create a filesystem structure that mirrors your metadata, making your audio library navigable both inside and outside your music player.
Frequently Asked Questions
The tool reads WAV files (RIFF header parsing for sample rate, channels, bit depth, duration), MP3 files (ID3v1 tag reading for title, artist, album, year, genre), and accepts OGG, FLAC, M4A, and AAC files for basic file information. WAV and MP3 receive the most detailed metadata extraction.
The tool is currently read-only for metadata inspection and supports batch file renaming based on existing tags. Writing new ID3 tags requires binary editing capabilities that go beyond the current implementation. For tag editing, consider dedicated tools like Mp3tag (desktop) or the Webamp metadata editor.
No. All metadata reading happens in your browser. The tool uses the FileReader API to read each file as an ArrayBuffer, then uses DataView to parse the binary headers directly in JavaScript. Your audio files are never transmitted over the network. The batch rename output is generated locally as a ZIP file.
Enter a pattern using curly-brace variables: {title}, {artist}, {album}, {year}, {index}. The tool replaces each variable with the corresponding metadata value from each file. If a file lacks a particular tag, the variable is replaced with 'Unknown'. The {index} variable inserts a zero-padded sequential number (001, 002, 003). The original file extension is preserved automatically.