OpsLog/app_tci_record.go

package main

// Recording a few seconds of the TCI stream to a WAV file.
//
// Counting frames proves a socket is delivering bytes. It does not prove those
// bytes are the receiver's audio, at the right rate, in the right order — a
// stream decoded with the channels swapped, the width wrong or the samples
// misaligned counts exactly as well as a correct one and sounds like a fan.
//
// So the test is a file the operator can play. It is the same reason the CW
// decoder was validated on the air rather than on a spectrogram.

import (
	"encoding/binary"
	"fmt"
	"math"
	"os"
	"path/filepath"
	"sync"
	"time"

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

// tciRec collects samples while a test recording is running.
type tciRec struct {
	mu      sync.Mutex
	active  bool
	rate    int
	samples []float32
	want    int // how many samples to collect before stopping
}

var tciRecorder tciRec

// RecordTCIAudio captures seconds of the TCI receive stream and writes a WAV
// next to the QSO recordings. Returns the path.
//
// The stream has to be open already — this listens to what is arriving rather
// than opening anything, so a recording can never leave a stream running that
// the operator did not ask for.
func (a *App) RecordTCIAudio(seconds int) (string, error) {
	if a.cat == nil {
		return "", fmt.Errorf("CAT not initialized")
	}
	if seconds <= 0 || seconds > 60 {
		seconds = 10
	}

	// Rate from the radio, not assumed: the file's header has to match what was
	// actually streamed or the recording plays at the wrong speed, which is the
	// one fault that would be blamed on the decoding.
	st := a.GetTCIAudioStatus()
	if !st.Running {
		return "", fmt.Errorf("open the TCI audio stream first")
	}
	rate := st.SampleRate
	if rate <= 0 {
		rate = 48000
	}

	tciRecorder.mu.Lock()
	if tciRecorder.active {
		tciRecorder.mu.Unlock()
		return "", fmt.Errorf("a test recording is already running")
	}
	tciRecorder.active = true
	tciRecorder.rate = rate
	tciRecorder.want = rate * seconds
	tciRecorder.samples = make([]float32, 0, tciRecorder.want)
	tciRecorder.mu.Unlock()

	err := a.cat.TCIAudioDo(func(t cat.TCIAudioController) error {
		s, ok := t.(interface{ SetTCIAudioSink(func(int, []float32)) })
		if !ok {
			return fmt.Errorf("this backend has no audio sink")
		}
		s.SetTCIAudioSink(func(_ int, samples []float32) {
			tciRecorder.mu.Lock()
			defer tciRecorder.mu.Unlock()
			if !tciRecorder.active {
				return
			}
			tciRecorder.samples = append(tciRecorder.samples, samples...)
		})
		return nil
	})
	if err != nil {
		tciRecorder.mu.Lock()
		tciRecorder.active = false
		tciRecorder.mu.Unlock()
		return "", err
	}

	// Wait for the samples rather than for the clock: a stream that stalls
	// halfway should produce a short file that says so, not a long one padded
	// with silence that hides it.
	deadline := time.Now().Add(time.Duration(seconds+5) * time.Second)
	for {
		tciRecorder.mu.Lock()
		got := len(tciRecorder.samples)
		want := tciRecorder.want
		tciRecorder.mu.Unlock()
		if got >= want || time.Now().After(deadline) {
			break
		}
		time.Sleep(100 * time.Millisecond)
	}

	tciRecorder.mu.Lock()
	tciRecorder.active = false
	pcm := tciRecorder.samples
	tciRecorder.samples = nil
	tciRecorder.mu.Unlock()
	_ = a.cat.TCIAudioDo(func(t cat.TCIAudioController) error {
		if s, ok := t.(interface{ SetTCIAudioSink(func(int, []float32)) }); ok {
			s.SetTCIAudioSink(nil)
		}
		return nil
	})

	if len(pcm) == 0 {
		return "", fmt.Errorf("nothing arrived on the stream")
	}
	path := filepath.Join(a.qsoRecDir(), fmt.Sprintf("tci-test-%s.wav", time.Now().Format("20060102-150405")))
	if err := writeMonoWAV(path, pcm, rate); err != nil {
		return "", err
	}
	applog.Printf("tci: wrote %.1f s of receive audio to %s (%d Hz)", float64(len(pcm))/float64(rate), path, rate)
	return path, nil
}

// writeMonoWAV writes float samples as 16-bit mono PCM.
//
// Its own writer rather than internal/audio's: that one is nailed to the voice
// keyer's rate, and a test recording written at the wrong rate would play back
// at the wrong speed — the one fault that looks exactly like a decoding error.
func writeMonoWAV(path string, samples []float32, rate int) error {
	data := make([]byte, len(samples)*2)
	for i, v := range samples {
		s := int(math.Round(float64(v) * 32767))
		if s > 32767 {
			s = 32767
		}
		if s < -32768 {
			s = -32768
		}
		binary.LittleEndian.PutUint16(data[i*2:], uint16(int16(s)))
	}
	var hdr [44]byte
	copy(hdr[0:], "RIFF")
	binary.LittleEndian.PutUint32(hdr[4:], uint32(36+len(data)))
	copy(hdr[8:], "WAVEfmt ")
	binary.LittleEndian.PutUint32(hdr[16:], 16) // PCM chunk size
	binary.LittleEndian.PutUint16(hdr[20:], 1)  // PCM
	binary.LittleEndian.PutUint16(hdr[22:], 1)  // mono
	binary.LittleEndian.PutUint32(hdr[24:], uint32(rate))
	binary.LittleEndian.PutUint32(hdr[28:], uint32(rate*2))
	binary.LittleEndian.PutUint16(hdr[32:], 2)  // block align
	binary.LittleEndian.PutUint16(hdr[34:], 16) // bits
	copy(hdr[36:], "data")
	binary.LittleEndian.PutUint32(hdr[40:], uint32(len(data)))

	f, err := os.Create(path)
	if err != nil {
		return err
	}
	defer f.Close()
	if _, err := f.Write(hdr[:]); err != nil {
		return err
	}
	_, err = f.Write(data)
	return err
}