Start work on improving recordings.

diskwriter/diskwriter_test.go

@@ -103,7 +103,7 @@ func TestCleanupOldRecordings(t *testing.T) {
 	}
 }
 
-func TestMixFrameClipsAndSumsSources(t *testing.T) {
+func TestMixFrameAppliesHeadroomForMultipleSources(t *testing.T) {
 	a := make(chan []byte, 1)
 	b := make(chan []byte, 1)
 	a <- pcmFrame(20000)
@@ -116,12 +116,79 @@ func TestMixFrameClipsAndSumsSources(t *testing.T) {
 
 	for i := 0; i < len(out); i += 2 {
 		got := int16(binary.LittleEndian.Uint16(out[i:]))
-		if got != 32767 {
-			t.Fatalf("sample %d = %d, expected clipped 32767", i/2, got)
+		if got != 28071 {
+			t.Fatalf("sample %d = %d, expected headroom-adjusted 28071", i/2, got)
 		}
 	}
 }
 
+func TestMixFrameLimiterPreservesNormalSpeechLevel(t *testing.T) {
+	a := make(chan []byte, 1)
+	a <- pcmFrame(12000)
+
+	out := mixFrame([]chan []byte{a})
+	for i := 0; i < len(out); i += 2 {
+		got := int16(binary.LittleEndian.Uint16(out[i:]))
+		if got != 12000 {
+			t.Fatalf("sample %d = %d, expected unchanged 12000", i/2, got)
+		}
+	}
+}
+
+func TestMixFrameHandlesQuietAndLoudSources(t *testing.T) {
+	a := make(chan []byte, 1)
+	b := make(chan []byte, 1)
+	a <- pcmFrame(1000)
+	b <- pcmFrame(20000)
+
+	out := mixFrame([]chan []byte{a, b})
+	for i := 0; i < len(out); i += 2 {
+		got := int16(binary.LittleEndian.Uint16(out[i:]))
+		if got != 14849 {
+			t.Fatalf("sample %d = %d, expected mixed quiet/loud sample 14849", i/2, got)
+		}
+	}
+}
+
+func TestMixFrameLimiterBoundsOverloadedSamples(t *testing.T) {
+	a := make(chan []byte, 1)
+	b := make(chan []byte, 1)
+	a <- pcmFrame(32000)
+	b <- pcmFrame(32000)
+
+	out := mixFrame([]chan []byte{a, b})
+	for i := 0; i < len(out); i += 2 {
+		got := int16(binary.LittleEndian.Uint16(out[i:]))
+		if got <= 0 || got > 32767 {
+			t.Fatalf("sample %d = %d, expected bounded positive sample", i/2, got)
+		}
+		if got >= 32767 {
+			t.Fatalf("sample %d = %d, expected limiter below hard clip", i/2, got)
+		}
+	}
+}
+
+func TestMixFrameConsumesOldestQueuedFrame(t *testing.T) {
+	source := make(chan []byte, 2)
+	source <- pcmFrame(1000)
+	source <- pcmFrame(2000)
+
+	out := mixFrame([]chan []byte{source})
+	if len(out) != bytesPerFrame {
+		t.Fatalf("mixed frame has length %d, expected %d", len(out), bytesPerFrame)
+	}
+
+	for i := 0; i < len(out); i += 2 {
+		got := int16(binary.LittleEndian.Uint16(out[i:]))
+		if got != 1000 {
+			t.Fatalf("sample %d = %d, expected oldest queued sample 1000", i/2, got)
+		}
+	}
+	if queued := len(source); queued != 1 {
+		t.Fatalf("queued frames after mix = %d, expected 1", queued)
+	}
+}
+
 func TestMixFrameReturnsNilForSilence(t *testing.T) {
 	if out := mixFrame(nil); out != nil {
 		t.Fatalf("expected nil silent frame, got %d bytes", len(out))
@@ -162,6 +229,45 @@ func TestRecorderCreatesPlayableOgg(t *testing.T) {
 	}
 }
 
+func TestSyntheticRecordingCreatesPlayableOgg(t *testing.T) {
+	if _, err := exec.LookPath("ffmpeg"); err != nil {
+		t.Skip("ffmpeg not installed")
+	}
+	if _, err := exec.LookPath("ffprobe"); err != nil {
+		t.Skip("ffprobe not installed")
+	}
+
+	result, err := RunSyntheticRecording(t.TempDir(), 3, 100*time.Millisecond)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if result.Metrics.DecoderStarts != 3 {
+		t.Fatalf("decoder starts = %d, expected 3", result.Metrics.DecoderStarts)
+	}
+	if result.Metrics.DecoderStops != 3 {
+		t.Fatalf("decoder stops = %d, expected 3", result.Metrics.DecoderStops)
+	}
+	if result.Metrics.DroppedMixedFrames != 0 {
+		t.Fatalf("dropped mixed frames = %d, expected 0", result.Metrics.DroppedMixedFrames)
+	}
+
+	cmd := exec.Command(
+		"ffprobe",
+		"-v", "error",
+		"-select_streams", "a:0",
+		"-show_entries", "stream=codec_name",
+		"-of", "default=noprint_wrappers=1:nokey=1",
+		result.Path,
+	)
+	out, err := cmd.Output()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if strings.TrimSpace(string(out)) != "opus" {
+		t.Fatalf("expected opus stream, got %q", strings.TrimSpace(string(out)))
+	}
+}
+
 func pcmFrame(sample int16) []byte {
 	out := make([]byte, bytesPerFrame)
 	for i := 0; i < len(out); i += 2 {