diff --git a/src/images_to_video.md b/src/images_to_video.md
index 6143741..1437bba 100644
--- a/src/images_to_video.md
+++ b/src/images_to_video.md
@@ -18,5 +18,5 @@ file 363.png
 where duration is in seconds
 
 ```bash
-ffmpeg -f concat -i concat.txt -vf "fps=25,format=yuv420p" -vsync vfr output.webm
+ffmpeg -y -f concat -i concat.txt -vf "fps=25,format=yuv420p" -vsync vfr output.webm
 ```
\ No newline at end of file
diff --git a/src/images_to_video.sh b/src/images_to_video.sh
index f31b6aa..9979313 100755
--- a/src/images_to_video.sh
+++ b/src/images_to_video.sh
@@ -2,7 +2,7 @@
 
 IN=$1
 [[ $IN ]]|| IN="concat.txt"
-FILES=$(cat $IN | grep file | awk '{print $2}')
+FILES=$(cat $IN | grep file | awk '{print $2}' | uniq)
 
 echo $FILES
 
diff --git a/src/mscz_to_mp3.py b/src/mscz_to_mp3.py
index 13a88a3..2c3e4e7 100644
--- a/src/mscz_to_mp3.py
+++ b/src/mscz_to_mp3.py
@@ -53,12 +53,20 @@ def separate_instruments(input_midi_path, output_folder):
     return outputs
 
 
-def change_instrument(input, output):
+def change_instrument(input, output, instrument=None):
     s = music21.converter.parse(input)
 
+    if instrument is None:
+        instrument = music21.instrument.Piano()
+
+    i=0
     for el in s.recurse():
         if 'Instrument' in el.classes: # or 'Piano'
-            el.activeSite.replace(el, music21.instrument.Piano())
+            try:
+                el.activeSite.replace(el, instrument)
+            except music21.exceptions21.StreamException:
+                i+=1
+                print(f"caught StreamException [{i}]")
 
     s.write('midi', output)
 
@@ -74,7 +82,7 @@ def create_audios(files, dest="out"):
         print(f"Converted {basename(el)}.mp3")
 
 
-def __main__(SCORE, OUT):
+def __main__(SCORE, OUT, instrument=None):
     os.makedirs(OUT, exist_ok=True)
 
     if SCORE.split(".")[-1] == "mscz":
@@ -90,7 +98,7 @@ def __main__(SCORE, OUT):
     midi_files = separate_instruments(MIDI_SCORE, OUT)
 
     for file in midi_files:
-        change_instrument(file, file)
+        change_instrument(file, file, instrument=instrument)
 
     print("=== Creating audios ===")
     create_audios(midi_files, OUT)
@@ -102,8 +110,21 @@ def __main__(SCORE, OUT):
 
 
 if __name__ == "__main__":
-    if len(sys.argv) < 3:
+    if len(sys.argv) != 3 and not (len(sys.argv) == 5 and sys.argv[3] == "--instrument"):
         print(f"Usage: {sys.argv[0]} <file.mscz> <out/>")
         exit(1)
 
-    __main__(sys.argv[1], sys.argv[2])
\ No newline at end of file
+    instrument=None
+    if len(sys.argv) > 3:
+        match sys.argv[4]:
+            case "piano":
+                instrument = music21.instrument.Piano()
+            case "organ":
+                instrument = music21.instrument.Organ()
+            case "flute":
+                instrument = music21.instrument.Flute()
+            case _:
+                print("Invalid instrument '", sys.argv[4], "'")
+                exit(1)
+
+    __main__(sys.argv[1], sys.argv[2], instrument=instrument)
\ No newline at end of file
diff --git a/src/superpose_audios.sh b/src/superpose_audios.sh
index ec27217..a24488e 100755
--- a/src/superpose_audios.sh
+++ b/src/superpose_audios.sh
@@ -3,7 +3,15 @@
 AUDIOS=out
 BASE_NAME="instrument_"
 BASE_OUT_NAME="combined_"
-VOLUME_2="0.1"
+VOLUME_2="0.3"
+ADDITIONAL=$1
+
+usage () {
+    echo "Usage: $0 <soliste.mp3>"
+    exit 1
+}
+
+[[ $ADDITIONAL ]] || usage
 
 
 combine () {
@@ -23,7 +31,11 @@ output_file () {
     echo "${AUDIOS}/${BASE_OUT_NAME}$1.mp3"
 }
 
-combine "$(input_file 1)" "$(input_file 3)" "$(output_file 1)"
-combine "$(input_file 2)" "$(input_file 3)" "$(output_file 2)"
-combine "$(input_file 3)" "$(input_file 1)" "$(output_file 3)"
-combine "$(input_file 4)" "$(input_file 1)" "$(output_file 4)"
+additional () {
+    echo $ADDITIONAL
+}
+
+combine "$(input_file 1)" "$(additional 3)" "$(output_file 1)"
+combine "$(input_file 2)" "$(additional 3)" "$(output_file 2)"
+combine "$(input_file 3)" "$(additional 1)" "$(output_file 3)"
+combine "$(input_file 4)" "$(additional 1)" "$(output_file 4)"