internal

Documentation

Index

• Constants
• func BandwidthForRate(sampleRate int) (int, error)
• func GenerateTOC(channels int, frameSize int) (byte, error)
• func GenerateTOCExt(mode, bandwidth, channels int, frameSizeSamples int) (byte, error)
• func ParseTOC(toc byte) (config int, stereo bool, countCode int)
• func ParseTOCConfig(config int) (mode, bandwidth, frameSize int)

Constants

const (
	ModeSILKOnly = 0
	ModeHybrid   = 1
	ModeCELTOnly = 2
)

Opus Mode types for TOC generation

const (
	BandwidthNarrowband    = 0 // NB: 8kHz
	BandwidthMediumband    = 1 // MB: 12kHz
	BandwidthWideband      = 2 // WB: 16kHz
	BandwidthSuperwideband = 3 // SWB: 24kHz
	BandwidthFullband      = 4 // FB: 48kHz
)

Opus bandwidth types for TOC generation

const (
	FrameSize2_5ms = 120
	FrameSize5ms   = 240
	FrameSize10ms  = 480
	FrameSize20ms  = 960
	FrameSize40ms  = 1920
	FrameSize60ms  = 2880
)

Frame Duration codes (RFC 6716 Section 3.1) These are frame sizes in samples at 48kHz.

const (
	ConfigCELT_Mono_20ms   = 20
	ConfigCELT_Stereo_20ms = 22
)

Legacy config constants (kept for backward compatibility in tests).

Functions

func BandwidthForRate

func BandwidthForRate(sampleRate int) (int, error)

BandwidthForRate returns the Opus bandwidth for a given sample rate.

func GenerateTOC

func GenerateTOC(channels int, frameSize int) (byte, error)

GenerateTOC creates a TOC byte for CELT-only fullband mode. This is the legacy interface. For multi-rate support, the encoder uses GenerateTOCExt internally and this function remains for backward compatibility.

frameSize is in samples at 48kHz. Only 960 (20ms) is supported by this function.

func GenerateTOCExt

func GenerateTOCExt(mode, bandwidth, channels int, frameSizeSamples int) (byte, error)

GenerateTOCExt creates a TOC byte for any supported mode/bandwidth/frame-size combination.

RFC 6716 Table 2 defines 32 configurations (0-31):

Configs  0- 3: SILK-only  NB  (10/20/40/60ms)
Configs  4- 7: SILK-only  MB  (10/20/40/60ms)
Configs  8-11: SILK-only  WB  (10/20/40/60ms)
Configs 12-13: Hybrid     SWB (10/20ms)
Configs 14-15: Hybrid     FB  (10/20ms)
Configs 16-19: CELT-only  NB  (2.5/5/10/20ms)
Configs 20-23: CELT-only  WB  (2.5/5/10/20ms)
Configs 24-27: CELT-only  SWB (2.5/5/10/20ms)
Configs 28-31: CELT-only  FB  (2.5/5/10/20ms)

func ParseTOC

func ParseTOC(toc byte) (config int, stereo bool, countCode int)

ParseTOC parses the Table Of Contents (TOC) byte. Returns configuration ID (0-31), stereo flag, and frame count code (0-3). RFC 6716 Section 3.1: TOC Byte: | config (5 bits) | s (1 bit) | c (2 bits) |

func ParseTOCConfig

func ParseTOCConfig(config int) (mode, bandwidth, frameSize int)

ParseTOCConfig extracts mode, bandwidth, and frame duration from a config number. Returns mode (SILK/Hybrid/CELT), bandwidth, and frame size in samples at 48kHz.