Bulk Convert OPUS to AAC Online — Raw AAC Stream

OPUS is a modern, open-source, royalty-free audio codec developed by Xiph.Org Foundation and IETF, standardized in RFC 6716 in September 2012. It was designed to replace both Vorbis (for music) and Speex (for voice), combining the best of both into a single codec. OPUS achieves exceptional quality at low bitrates—transparent quality at 128 kbps for music, and near-transparent voice at just 32 kbps. It supports bitrates from 6 kbps to 510 kbps and sample rates from 8 kHz to 48 kHz.

Learn more: Opus on Wikipedia

OPUS is the mandatory audio codec for WebRTC, making it the native format for video calls (Discord, Zoom, Google Meet, Teams) and voice messaging (WhatsApp, Telegram). It excels at both speech and music, adapting dynamically to content. OPUS files use the Ogg container (.opus extension) and play in all modern browsers (Chrome, Firefox, Edge, Safari 15+), VLC, and most media players from 2015 onward. For streaming, voice chat, podcasts, and any application where quality-per-bit matters, OPUS is the current state of the art.

AAC (Advanced Audio Coding) is the successor to MP3, standardized by MPEG in 1997 and subsequently adopted as the default format for YouTube, Apple Music, and most streaming platforms. Achieving compression ratios of 8:1 to 12:1, AAC delivers better quality than MP3 at the same bitrate—128 kbps AAC typically matches 160-192 kbps MP3. It's the underlying codec in M4A files (AAC audio in an MP4 container) and the audio component of most video files.

Learn more: AAC on Wikipedia

Raw AAC files (with .aac extension) are less common than containerized versions (.m4a, .mp4), but they're used in broadcast, streaming pipelines, and as extracted audio from video. AAC supports sample rates up to 96 kHz and up to 48 audio channels, including 5.1 and 7.1 surround configurations—making it suitable for professional multichannel content. For maximum compatibility with minimal quality loss, AAC at 256 kbps is often the sweet spot between MP3's universality and FLAC's fidelity.