types

Documentation

Overview

Package types defines small, dependency-free enumerations shared across the gopus packages. It exists purely to break import cycles: the codec, range coder, SILK, and CELT layers all need to agree on the coding mode, audio bandwidth, and signal hint without importing one another. Keeping these in a leaf package with no internal imports lets every layer depend on it freely.

The values here mirror the corresponding libopus enumerations so that gopus stays bit-exact and behavior-compatible with the reference implementation.

Index

• type Bandwidth
• type Mode
• type Signal

Types

type Bandwidth

type Bandwidth uint8

Bandwidth represents the coded audio bandwidth, which fixes the audio frequency range and therefore the internal sample rate used by the codec.

The five values match the OPUS_BANDWIDTH_* enumeration in include/opus_defines.h (NARROWBAND through FULLBAND) and the TOC bandwidth ranges in RFC 6716 Section 2. As with Mode, the uint8 storage is an implementation choice for a small enumeration, not a wire-format constraint.

const (
	BandwidthNarrowband    Bandwidth = iota // 4 kHz audio, 8 kHz sample rate (OPUS_BANDWIDTH_NARROWBAND).
	BandwidthMediumband                     // 6 kHz audio, 12 kHz sample rate (OPUS_BANDWIDTH_MEDIUMBAND).
	BandwidthWideband                       // 8 kHz audio, 16 kHz sample rate (OPUS_BANDWIDTH_WIDEBAND).
	BandwidthSuperwideband                  // 12 kHz audio, 24 kHz sample rate (OPUS_BANDWIDTH_SUPERWIDEBAND).
	BandwidthFullband                       // 20 kHz audio, 48 kHz sample rate (OPUS_BANDWIDTH_FULLBAND).
)

type Mode

type Mode uint8

Mode represents the Opus coding mode in effect for a frame, selecting which of the two underlying codecs (SILK, CELT, or both) produces the frame.

The three modes correspond to the TOC configuration ranges defined in RFC 6716 Section 3.1 and to the MODE_SILK_ONLY / MODE_HYBRID / MODE_CELT_ONLY constants in libopus src/opus_private.h. Mode is stored as a uint8 because it is a small closed enumeration; the underlying width is not bit-exact-critical (it never crosses the entropy-coded wire), only the value mapping is.

const (
	ModeSILK   Mode = iota // SILK-only mode (TOC configs 0-11, libopus MODE_SILK_ONLY).
	ModeHybrid             // Hybrid SILK+CELT mode (TOC configs 12-15, libopus MODE_HYBRID).
	ModeCELT               // CELT-only mode (TOC configs 16-31, libopus MODE_CELT_ONLY).
)

type Signal

type Signal int

Signal is the input signal-type hint passed to the encoder via OPUS_SET_SIGNAL. It biases the SILK/CELT mode decision toward speech or music but does not by itself force a mode.

Signal is a plain int so the constant values match libopus exactly: the magic numbers below are the OPUS_AUTO / OPUS_SIGNAL_VOICE / OPUS_SIGNAL_MUSIC values from include/opus_defines.h. The exact integers matter because the public encoder control API compares against them directly; the constants are part of the ABI rather than arbitrary tags.

const (
	// SignalAuto lets the encoder detect the signal type automatically
	// (libopus OPUS_AUTO).
	SignalAuto Signal = -1000
	// SignalVoice hints that the input is speech, biasing toward SILK mode
	// (libopus OPUS_SIGNAL_VOICE).
	SignalVoice Signal = 3001
	// SignalMusic hints that the input is music, biasing toward CELT mode
	// (libopus OPUS_SIGNAL_MUSIC).
	SignalMusic Signal = 3002
)