> The format has three different modes: speech, hybrid, and CELT. The basic speech mode is pure SILK, up to 8 kHz, while the hybrid speech mode combines SILK fo

> The format has three different modes: speech, hybrid, and CELT. The basic speech mode is pure SILK, up to 8 kHz, while the hybrid speech mode combines SILK for the speech and uses CELT for the frequency range above 8 kHz, allowing an easy fallback to pure SILK at very low bitrates. > Opus combines the speech-oriented linear predictive coding SILK algorithm, and the lower-latency, MDCT-based CELT algorithm, switching between or combining them as needed for maximum efficiency. https://en.wikipedia.org/wiki/Opus_(audio_format)#Features https://en.wikipedia.org/wiki/Opus_(audio_format)#Features