Convert M4A to OPUS Online
Convert your iTunes and Apple Music M4A library to modern Opus, free and in your browser.
.m4a · up to 100 MB
What it's for
Your Apple library in an open format
iTunes library to Discord
Convert your iTunes M4A songs to Opus for Discord bots, in-chat playback, and audio projects.
Bandwidth optimization
Opus delivers better quality than AAC at low bitrates. Ideal for streaming on limited connections.
Podcast to modern platforms
Re-encode M4A podcast episodes to Opus for platforms that prefer or require the modern codec.
100% private, no DRM bypass
Only works with DRM-free M4A files. FFmpeg.wasm processes locally. No files are uploaded to any server.
How it works
Three steps, no hassle
Upload your M4A file
Drag or select your .m4a. Works with iTunes songs, DRM-free Apple Music downloads, Apple Podcasts episodes, and iPhone Voice Memos recordings.
FFmpeg converts AAC to Opus
The AAC-LC audio in the M4A is decoded and re-encoded to Opus 48 kHz using FFmpeg.wasm. Entirely in your browser, no server uploads.
Download the resulting .opus file
Get Opus audio ready for Discord, VoIP apps, low-bandwidth streaming, and any modern platform.
FAQ
Got questions?
Yes, as long as the songs have no DRM (Digital Rights Management). Songs purchased before April 2009 may have FairPlay DRM and cannot be converted directly. Songs purchased after Apple introduced iTunes Plus (DRM-free) in April 2009 are standard AAC-LC in M4A format, fully convertible. Apple Music subscription downloads do have DRM and cannot be converted.
iTunes Store files use AAC-LC at 256 kbps for purchases since 2009 (iTunes Plus quality). Apple Music offline downloads use AAC at 256 kbps. Apple Podcasts episodes vary from 64 to 192 kbps depending on the producer. iPhone Voice Memos recordings use AAC-LC at 32 kbps (compressed) or 128 kbps (lossless quality setting in iOS settings).
At low bitrates (32–96 kbps), Opus is generally superior to AAC-LC in perceptual quality, especially for voice. MUSHRA listening tests conducted by the IETF and independently verified show that Opus at 64 kbps surpasses AAC-LC at 64 kbps and is comparable to AAC-LC at 128 kbps for mixed music. At 128 kbps or higher, the difference is minimal and both are practically transparent for most listeners.
Discord has used Opus for all voice audio since 2015, and .opus attachments in Discord chat play inline without downloading. Discord bots (discord.py, discord.js) can stream Opus audio directly to voice channels with lower CPU usage than other formats. Converting your M4A library to Opus simplifies integration with Discord music bots.
M4A is an MPEG-4 container that can hold both AAC (lossy) and ALAC (Apple Lossless Audio Codec, lossless). The .m4a extension is used for both; the difference is the internal codec. ALAC shows codec_name alac in FFmpeg. If your M4A is ALAC (lossless), converting to Opus introduces lossy compression. To identify whether your M4A is AAC or ALAC, use MediaInfo or iTunes file properties: ALAC shows 'Apple Lossless' while AAC shows 'AAC' or 'MPEG-4 Audio'.
Technically yes, but you must respect the content's copyright. Many podcasters distribute episodes under Creative Commons licenses or with explicit redistribution permission. Converting for personal use (listening on devices without M4A support, archiving, syncing to specific platforms) is generally acceptable. For public redistribution, check the podcast's license.
Convert M4A to Opus: bring your iTunes and Apple Music library to Discord, VoIP, and modern platforms
M4A (MPEG-4 Audio) is a file extension introduced by Apple in 2001 to distinguish MPEG-4 audio-only files from MP4 files that can contain video. The container is technically MPEG-4 Part 14 (ISO 14496-14) and can encapsulate either AAC (Advanced Audio Coding, standard lossy encoding) or ALAC (Apple Lossless Audio Codec, lossless, introduced by Apple in 2004 and released as open source in October 2011). iTunes Store began selling songs in AAC-LC M4A with FairPlay DRM in April 2003; with the launch of iTunes Plus on May 30, 2007, Apple began offering DRM-free songs at 256 kbps, and in January 2009 the entire iTunes library became DRM-free, making it the world's largest DRM-free digital music catalog at the time. Apple Music, launched June 30, 2015, distributes music in AAC at 256 kbps with FairPlay DRM for offline listening and streaming. Apple Podcasts (formerly iTunes Podcasts) distributes episodes in M4A/AAC, MP3, or MP4 depending on the producer. iPhone Voice Memos recordings, saved as M4A since iOS 12 (September 2018), use AAC-LC at 32 kbps (compressed mode) or 128 kbps (high quality mode in iOS settings).
AAC (Advanced Audio Coding) was standardized as ISO 14496-3 in 1997 as the successor to MP3 in the MPEG-4 standard. AAC-LC (Low Complexity) is the most universally compatible profile and the one used by iTunes, Apple Music, YouTube, Spotify, and virtually all digital distribution platforms. AAC offers better quality than MP3 at the same bitrate: AAC at 128 kbps is comparable to MP3 at 192 kbps in perceptual quality. However, Opus, standardized as RFC 6716 in September 2012, offers better efficiency than AAC at low to medium bitrates: Opus at 64 kbps matches or surpasses AAC at 128 kbps; Opus at 96 kbps is practically transparent for most musical material. For VoIP and Discord applications where audio travels at 64 kbps or less, the difference between AAC and Opus is significant: Discord, Zoom, Google Meet, and virtually all modern WebRTC infrastructure have adopted Opus as the only supported low-latency audio codec precisely because its performance at low bitrates surpasses all alternatives.
Convertir.ai runs the M4A→Opus conversion entirely in the browser using FFmpeg.wasm. The technical process: FFmpeg opens the MPEG-4 Part 14 container of the M4A, detects whether the audio is AAC (codec_name aac, profile aac_low for LC or aac_he for HE-AAC) or ALAC (codec_name alac), decodes the audio stream to float32 PCM at the original sample rate (typically 44.1 kHz for iTunes music or 48 kHz for Apple Music content), applies resampling to 48 kHz if needed using FFmpeg's SWR resampler with kaiser windowed sinc algorithm for maximum quality, and re-encodes with libopus in audio mode (CELT, optimized for full-spectrum music) at 128 kbps by default for transparent quality. The result is a .opus file in OGG container conforming to RFC 7845, with iTunes metadata transferred to OpusTags (title, artist, album, year, track number). For M4A with HE-AAC (some podcasts and internet radio streams), FFmpeg correctly decodes including the SBR (Spectral Band Replication) extension, preserving the reconstructed high-frequency content. The service is completely free, no file limits, no signup, no watermark, and no server-side processing.