OpsLog/app_digi_txaudio.go

package main

// ── Transmit audio for a digital program, over the radio's own link ────────
//
// An IC-705, IC-7610 or IC-7760 reached over Ethernet has no sound card on this
// PC: its receive audio arrives on UDP 50003 and its transmit audio has to go
// back the same way. OpsLog already does both — the RX monitor plays the stream,
// the voice keyer and the talk button send into it.
//
// WSJT-X cannot. It drives the rig through the CAT OpsLog shares (rigctld), so
// it can tune and key perfectly well, and then has nowhere to put its audio: it
// needs a Windows audio endpoint and the radio is not one. A virtual cable
// bridges the gap — WSJT-X's output device is the cable, and OpsLog captures the
// cable's other side and streams it to the rig. That is what wfview asks of its
// users too; nothing short of a signed kernel driver can present a sound card,
// and OpsLog is neither signed nor a driver.
//
// The route is armed by PTT rather than left running. Streaming continuously
// would put whatever the cable carries — the desktop's notification sounds, an
// idle WSJT-X's silence, another program that grabbed the same cable — into a
// transmitter the moment anything else keyed it. PTT is also exactly the signal
// available: WSJT-X keys through us, so we know.

import (
	"strings"

	"hamlog/internal/applog"
	"hamlog/internal/audio"
	"hamlog/internal/cat"
)

// digiTXSender returns the radio's live-audio sender, or nil when this station
// is not set up for the path at all.
//
// Three things have to be true, and none of them is an error worth reporting on
// every over: a capture device is configured, the radio takes audio over its
// link, and its audio session is actually open.
func (a *App) digiTXSender() (dev string, send func([]byte) error) {
	if a.audioMgr == nil || a.cat == nil {
		return "", nil
	}
	cfg, err := a.GetAudioSettings()
	if err != nil {
		return "", nil
	}
	dev = strings.TrimSpace(cfg.DigiInput)
	if dev == "" {
		return "", nil
	}
	type sender interface {
		TXAudioSender() (func([]byte) error, error)
	}
	if derr := a.cat.IcomDo(func(ic cat.IcomController) error {
		p, ok := ic.(sender)
		if !ok {
			return nil // not a radio that takes audio over its link
		}
		fn, serr := p.TXAudioSender()
		if serr != nil {
			// The stream is not open — RX audio is switched off in Settings ▸ CAT.
			// Said once per over at most, and it names the fix.
			applog.Printf("digi audio: %v", serr)
			return nil
		}
		send = fn
		return nil
	}); derr != nil {
		return "", nil
	}
	if send == nil {
		return "", nil
	}
	return dev, send
}

// startDigiTXAudio begins piping the configured capture device into the radio.
//
// Called after the rig is keyed, so a failure here leaves a transmitting radio
// with no audio rather than audio going into a receiver — and it is reported
// rather than silently dropped, because a station that transmits silence for a
// whole evening has no other way to find out.
func (a *App) startDigiTXAudio() {
	dev, send := a.digiTXSender()
	if send == nil {
		return
	}
	if err := a.audioMgr.StartTXAudioNetwork(dev, send); err != nil {
		applog.Printf("digi audio: %q could not be opened, the over will be silent: %v", dev, err)
		return
	}
	a.digiTX.Store(true)
	applog.Printf("digi audio: %q → the radio, for as long as the shared CAT holds PTT", dev)
}

// stopDigiTXAudio ends the route. Only when WE started it: the talk button and
// the voice keyer use the same one, and unkeying a digital over must not cut
// off a message the operator is playing by hand.
func (a *App) stopDigiTXAudio() {
	if !a.digiTX.Swap(false) {
		return
	}
	if a.audioMgr != nil {
		a.audioMgr.StopTXAudio()
	}
}

// ListDigiInputDevices is the dropdown behind the setting: the capture devices,
// which for this purpose means the virtual cable WSJT-X plays into.
//
// The radio itself is deliberately NOT offered. It is a source of receive audio,
// and picking it here would ask OpsLog to send the radio its own output.
func (a *App) ListDigiInputDevices() ([]audio.Device, error) {
	return audio.ListInputDevices()
}