Stretch samples a bit better with the GBA's 32768Hz

pkg/worker/media/media.go

@@ -82,8 +82,9 @@ func DefaultOpus() (*opus.Encoder, error) {
 }
 
 // frame calculates an audio stereo frame size, i.e. 48k*frame/1000*2
+// with round(x / 2) * 2 for the closest even number
 func frame(hz int, frame float32) int {
-	return int(math.Round(float64(hz) * float64(frame) / 1000 * 2))
+	return int(math.Round(float64(hz)*float64(frame)/1000/2) * 2 * 2)
 }
 
 // stretch does a simple stretching of audio samples.

pkg/worker/media/media_test.go

@@ -192,7 +192,7 @@ func TestBufferWrite(t *testing.T) {
 			buf.write(samplesOf(w.sample, w.len), func(s samples) { lastResult = s })
 		}
 		if !reflect.DeepEqual(test.expect, lastResult) {
-			t.Errorf("not expted buffer, %v != %v", lastResult, test.expect)
+			t.Errorf("not expted buffer, %v != %v, %v", lastResult, test.expect, buf.s)
 		}
 	}
 }
@@ -217,17 +217,20 @@ func samplesOf(v int16, len int) (s samples) {
 	return
 }
 
-func Test_frame(t *testing.T) {
+func TestFrame(t *testing.T) {
 	type args struct {
 		hz    int
-		frame int
+		frame float32
 	}
 	tests := []struct {
 		name string
 		args args
 		want int
 	}{
-		{name: "mGBA", args: args{hz: 32768, frame: 10}, want: 654},
+		{name: "mGBA", args: args{hz: 32768, frame: 10}, want: 656},
+		{name: "mGBA", args: args{hz: 32768, frame: 5}, want: 328},
+		{name: "mGBA", args: args{hz: 32768, frame: 2.5}, want: 164},
+		{name: "nes", args: args{hz: 48000, frame: 2.5}, want: 240},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {