Simple watermarker latency test.

Signed-off-by: Stefan Westerfeld <stefan@space.twc.de>

src/ttfb-test.py

+#!/usr/bin/env python3
+
+# test how long the watermarker takes until the first audio sample is available
+
+import subprocess
+import time
+
+for i in range (10):
+    start_time = time.time()
+    proc = subprocess.Popen (["audiowmark", "add", "test/T01__09_sing_sang_sung.flac.wav", "-", "f0"], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+
+    # we wait for actual audio data, so we read somewhat larger amount of data that the wave header
+    x = proc.stdout.read (1000)
+    end_time = time.time()
+    print (end_time - start_time, x[0:4], len (x))