fm-rds-tx/internal/rds/config.go

package rds

// RDSConfig holds configuration data used to build the RDS data stream.
// Covers IEC 62106 groups 0A, 2A, 3A, 4A, 10A, 11A, 14A (everything except TMC/EWS).
type RDSConfig struct {
	// --- Group 0A: Basic tuning & switching ---

	// Program Identification – 16-bit station identifier.
	PI uint16

	// Program Service name (8 ASCII characters, padded with spaces).
	PS string

	// Program Type (0-31 standard RDS PTY values).
	PTY uint8

	// Traffic Program (TP) — this station carries traffic announcements.
	TP bool

	// Traffic Announcement (TA) — a traffic announcement is currently on air.
	// When TA transitions to true, receivers with TP-seek interrupt CD/other media.
	TA bool

	// Music/Speech switch: true = music, false = speech.
	// Receivers may adjust EQ or display accordingly.
	MS bool

	// Decoder Identification (DI): 4-bit field sent across 4 group 0A segments.
	//   bit 0 (d3): stereo (1) vs mono (0)
	//   bit 1 (d2): artificial head (1) vs normal (0)
	//   bit 2 (d1): compressed (1) vs not (0)
	//   bit 3 (d0): dynamic PTY (1) vs static (0)
	DI uint8

	// Alternative Frequencies list. Up to 25 frequencies in MHz (e.g. 93.3, 95.7).
	// Transmitted in group 0A block C (two AF codes per group).
	// Enables automatic retuning when signal weakens.
	AF []float64

	// --- Group 2A: RadioText ---

	// RadioText (up to 64 characters). Current song, info, etc.
	RT string

	// --- Group 4A: Clock-Time & Date ---

	// CTEnabled: transmit UTC clock-time once per minute.
	CTEnabled bool

	// CTOffsetHalfHours: local time offset from UTC in half-hours (-24..+24).
	// E.g. CET = +2, CEST = +4. Auto-detected from OS if zero.
	CTOffsetHalfHours int8

	// --- Group 10A: Program Type Name ---

	// PTYN: 8-character custom label for the program type.
	// Overrides the standard PTY label on receivers that support it.
	// Empty = don't transmit group 10A.
	PTYN string

	// --- Group 11A + 3A: RT+ (RadioText Plus) ---

	// RTPlusEnabled: automatically parse RT into semantic tags (artist, title, etc.)
	// and transmit RT+ groups (11A) with ODA announcements (3A).
	RTPlusEnabled bool

	// RTPlusSeparator: string used to split RT into artist/title.
	// Default "-". E.g. "Depeche Mode - Enjoy The Silence" → artist/title.
	RTPlusSeparator string

	// --- Group 14A/14B: Enhanced Other Networks (EON) ---

	// EON: information about other stations in the network.
	// Enables cross-station TA switching and AF lists for other programs.
	EON []EONEntry

	// --- Encoder internal ---

	// SampleRate that the encoder will work against. Defaults to 228000 when zero.
	SampleRate float64
}

// EONEntry describes another station in the network for EON (group 14A/14B).
type EONEntry struct {
	PI  uint16    // Program Identification of the other station
	PS  string    // Program Service name (8 chars)
	PTY uint8     // Program Type
	TP  bool      // Traffic Program flag
	TA  bool      // Traffic Announcement flag (live-updated for cross-TA switching)
	AF  []float64 // Alternative Frequencies for the other station
}

// DefaultConfig returns a minimal config with sane defaults.
func DefaultConfig() RDSConfig {
	return RDSConfig{
		PI:              0x1234,
		PS:              "FM-RDS",
		RT:              "Go-based MPX",
		PTY:             0,
		TP:              false,
		TA:              false,
		MS:              true, // music by default
		DI:              0x01, // stereo
		CTEnabled:       true,
		RTPlusEnabled:   true,
		RTPlusSeparator: " - ",
		SampleRate:      228000,
	}
}