script for measuring latency

examples/measure_latency.jl

@@ -0,0 +1,67 @@
+using PortAudio
+using DSP
+
+function create_measure_signal()
+    signal = zeros(Float32, 1000)
+    for i in 1:3
+        signal = vcat(signal, rand(Float32, 100), zeros(Float32, i*3000))
+    end
+    return signal
+end
+
+function measure_latency(in_latency = 0.1, out_latency=0.1, blocksize = 32; is_warmup = false)
+
+    in_stream = PortAudioStream(1,0; latency=in_latency, blocksize=32)
+    out_stream = PortAudioStream(0,1; latency=out_latency, blocksize=32)
+
+    cond = Base.Event()
+
+    writer_start_time = Int64(0)
+    reader_start_time = Int64(0)
+
+    reader = Threads.@spawn begin
+        wait(cond)
+        writer_start_time = time_ns() |> Int64
+        return read(in_stream, 100000)
+    end
+
+    signal = create_measure_signal()
+    writer = Threads.@spawn begin
+            wait(cond)
+            reader_start_time = time_ns() |> Int64
+            write(out_stream, signal)
+    end
+
+    notify(cond)
+
+    wait(reader)
+    wait(writer)
+
+    recorded = collect(reader.result)[:,1]
+    
+    close(in_stream)
+    close(out_stream)
+
+    diff = reader_start_time - writer_start_time |> abs
+
+    diff_in_ms = diff / 10^6 # 1 ms = 10^6 ns
+
+    if !is_warmup && diff_in_ms > 1
+        @warn "Threads start time difference $diff_in_ms ms is bigger than 1 ms"
+    end
+
+    delay = finddelay(recorded, signal) / 48000
+
+    return trunc(Int, delay * 1000)# result in ms
+end
+
+measure_latency(0.1, 0.1, 32; is_warmup = true) # warmup
+
+for in_latency in [0.1, 0.01, 0.005]
+    for out_latency in [0.1, 0.01, 0.005]
+        for blocksize in [32]
+            measure = measure_latency(in_latency, out_latency, blocksize)
+            println("$measure ms latency for in_latency=$in_latency, out_latency=$out_latency, blocksize=$blocksize")
+        end
+    end
+end