diff --git a/fig/synth-shorttime.png b/fig/synth-shorttime.png
index ab13e05..ac809d7 100644
Binary files a/fig/synth-shorttime.png and b/fig/synth-shorttime.png differ
diff --git a/fig/synth-single.png b/fig/synth-single.png
index 1556544..e6b9279 100644
Binary files a/fig/synth-single.png and b/fig/synth-single.png differ
diff --git a/generate.py b/generate.py
index cdc79b2..f43f85e 100644
--- a/generate.py
+++ b/generate.py
@@ -1,4 +1,13 @@
 import soundbox
+import sys
+
+if len(sys.argv) != 2:
+    print(f"""Utilisation: {sys.argv[0]} [output]
+
+Génère un morceau au synthétiseur dans le fichier [output].""")
+    sys.exit(1)
+
+output_file = sys.argv[1]
 
 
 def sine(dur, freq, value=1):
@@ -9,7 +18,7 @@ def sine(dur, freq, value=1):
 
 def square(dur, freq, value=1):
     return soundbox.envelope(
-        attack=.01, decay=.2, release=.2,
+        attack=.2, decay=.2, release=.2,
         signal=soundbox.square(dur, freq, value))
 
 
@@ -37,9 +46,9 @@ for shift in (.5, 4.5):
     for i in range(len(chords_l)):
         soundbox.add_signal(signal, start=i / 2 + shift,
             source=soundbox.chord(
-                instr=square, dur=.6,
+                instr=square, dur=.4,
                 freqs=soundbox.note_freqs(chords_l[i]),
-                value=.05
+                value=.04
             ))
 
     for i in range(len(chords_r)):
@@ -47,7 +56,7 @@ for shift in (.5, 4.5):
             source=soundbox.chord(
                 instr=sine, dur=1.1,
                 freqs=soundbox.note_freqs(chords_r[i]),
-                value=.6
+                value=.5
             ))
 
-soundbox.save_signal('out.wav', signal)
+soundbox.save_signal(output_file, signal)
diff --git a/sounds/piano.wav b/sounds/piano.wav
new file mode 100644
index 0000000..a37cce7
Binary files /dev/null and b/sounds/piano.wav differ
diff --git a/sounds/synth.wav b/sounds/synth.wav
index 7caf414..aa3449e 100644
Binary files a/sounds/synth.wav and b/sounds/synth.wav differ