--- title: One codec to rule them all? seoTitle: One codec to rule them all? | Argus Archive summary: Opus in Ogg beats MP3 and AAC for voice archiving—smaller files, better clarity, open standard. Ideal for Teams compliance recording and long-term storage. date: 2025-06-30 updated: 2026-06-10 category: technology-innovation author: gabor-moczar image: /media/uploads/2025/06/image-1.jpg --- ## Why Voice Codecs Like Opus in Ogg Are Better for Archiving Conversations Than General Audio Codecs Like MP3 or AAC When evaluating audio archiving solutions for compliance recording — such as those used for Microsoft Teams, Zoom, Cisco Webex or trader voice — the choice of audio codec and container format can have a lasting impact on storage efficiency, transcription accuracy, and long-term accessibility. A common mistake is to archive voice recordings using general-purpose audio formats like MP3. While MP3 is widely supported, it was designed for music and struggles to deliver the clarity and efficiency needed for spoken audio. In contrast, modern voice codecs like **Opus**, particularly when stored in the open **Ogg** container format, are purpose-built for compressing speech, making them far more suitable for storing conversations and call recordings. ## Voice Codecs Are Built for Speech Voice codecs are specifically engineered to handle the unique characteristics of human speech. Unlike music codecs that need to preserve wide dynamic and frequency ranges, voice codecs exploit the predictable patterns in spoken language to achieve better compression with minimal perceptual loss. Benefits of voice codecs include: - **Superior compression at low bitrates**: Voice codecs maintain intelligibility at as low as 6–16 kbps. In comparison, MP3 often requires 96–128 kbps to deliver acceptable speech clarity. - **Low latency**: Voice codecs like Opus are designed for real-time communication, enabling quick playback and near-instantaneous transcription workflows. - **Built-in error resilience**: Features like packet loss concealment make voice codecs ideal for archiving calls originating from variable network conditions. ## Opus: The Ideal Codec for Archiving Speech **Opus** is a modern, open-source codec developed by the [Xiph.org Foundation](https://www.xiph.org/)[^1], and is now a standard for internet audio (RFC 6716). It combines the strengths of two earlier codecs: **SILK** (used by Skype) for speech and **CELT** for low-latency audio. Key strengths of Opus include: - **Efficient bitrate scalability**: From 6 kbps for narrowband speech to 510 kbps for high-fidelity stereo. - **Wide audio bandwidth**: Supports 8 to 48 kHz sampling rates and adjusts dynamically depending on content. - **Outstanding voice quality**: [Studies have shown Opus outperforms MP3 and even AAC](https://opus-codec.org/comparison/) at lower bitrates when used for speech[^2]. - **Royalty-free and open**: Opus is unencumbered by licensing, making it future-proof for archiving use. ## Ogg: A Practical Container for Opus While Opus can be used in multiple container formats, **Ogg** is the most common and well-supported option for archival use: - **Open format**: No patents or licensing concerns. No vendor lock in. - **Broad compatibility**: Supported by all major browsers, operating systems — including mobile — and tools like FFmpeg, VLC. ## Why MP3 Is Not Suitable for Archiving Speech MP3 is nearly universal, but not optimized for speech: - **Inefficient at low bitrates**: MP3 sacrifices voice clarity below 64–96 kbps. - **Lacks voice-centric features**: No built-in voice activity detection or packet loss concealment. - **Legacy design**: MP3’s architecture and licensing history make it less appealing for modern archiving solutions, despite patents now expiring. ## AAC: A Good General Codec, But Not the Best for Voice [**AAC** (Advanced Audio Coding)](https://en.wikipedia.org/wiki/Advanced_Audio_Coding)[^3] is a strong general-purpose codec and is often used in streaming, broadcasting, and mobile apps. Compared to MP3, it achieves better quality at similar bitrates. However, when used for archiving speech: - **It performs well at higher bitrates** (typically above 96 kbps), but less efficiently than Opus at lower bitrates. - **It's not royalty-free** — while some AAC profiles (like AAC-LC) have expired patents, implementations may still carry licensing requirements. - **It’s optimized for music** and not as feature-rich for real-time speech applications or low-latency transcription. In short, AAC is good, but **Opus is better for speech and free to use**. ## Sample Audio Files for Comparison Here you can find sample audio files to compare the same source encoded with the 3 different codecs mentioned in this article. Source audio 44 KHz, 32 bit Mono PCM WAV, **12 Mbyte** MP3 audio Lowest possible bitrate, 32 Kbps, **280 Kbyte** AAC audio Lowest possible bitrate, 16 Kbps, **146 Kbyte** Opus audio 16 Kbps, **148 Kbyte** ## A Two-Step Compression Approach for Voice Archiving A best practice in compliance-grade audio archiving is to use **two different encoding stages**: 1. **High-Quality Recording for Transcription**
When a call or conversation is captured, it should first be stored in a high-quality format. This ensures maximum fidelity for downstream processing such as speech-to-text transcription, speaker separation, or sentiment analysis. 2. **Low-Bitrate Archival Version for Long-Term Storage**
After transcription and processing, a second archival version can be generated. This version is compact, efficient, and retains sufficient quality for audit, playback, or legal hold purposes. This two-tier strategy offers the best of both worlds: high-quality inputs for AI/ML processing and highly efficient archival for long-term compliance retention. ## Final Thoughts As enterprise communications continue shifting to platforms like Microsoft Teams, scalable and cost-effective archiving becomes increasingly important. Choosing the right codec isn't just a technical detail — it has direct implications for: - **Storage costs** - **Transcription accuracy** - **Playback experience** - **Regulatory defensibility** By adopting **Opus in Ogg** for long-term conversation storage and avoiding general-purpose codecs like MP3, organizations can build compliance recording systems that are modern, efficient, and future-proof.io is stored become strategic. Choosing an open, efficient, voice-optimized format like **Opus in Ogg** is a small decision that can yield significant long-term benefits in cost, quality, and flexibility. ## References [^1]: [https://www.xiph.org/](https://www.xiph.org/) [^2]: [https://opus-codec.org/comparison/](https://opus-codec.org/comparison/) [^3]: [https://en.wikipedia.org/wiki/Advanced_Audio_Coding](https://en.wikipedia.org/wiki/Advanced_Audio_Coding)