added WrongContainer exception that is raised by converter funcs

#205
#240

musicalgestures/_utils.py

@@ -357,6 +357,11 @@ def show(self):
         return self.figure
 
 
+class WrongContainer(Exception):
+    def __init__(self, message):
+        self.message = message
+
+
 def convert(filename, target_name, overwrite=False):
     """
     Converts a video to another format/container using ffmpeg.
@@ -404,6 +409,8 @@ def convert_to_avi(filename, target_name=None, overwrite=False):
         return filename
     if not target_name:
         target_name = of + '.avi'
+    elif os.path.splitext(target_name)[1].lower() != '.avi':
+        raise WrongContainer(f"requested target container is NOT .avi but {os.path.splitext(target_name)[1]}.")
     if not overwrite:
         target_name = generate_outfilename(target_name)
     cmds = ['ffmpeg', '-y', '-i', filename, "-c:v", "mjpeg",
@@ -432,13 +439,16 @@ def convert_to_mp4(filename, target_name=None, overwrite=False):
         return filename
     if not target_name:
         target_name = of + '.mp4'
+    elif os.path.splitext(target_name)[1].lower() != '.mp4':
+        raise WrongContainer(f"requested target container is NOT .mp4 but {os.path.splitext(target_name)[1]}.")
     if not overwrite:
         target_name = generate_outfilename(target_name)
     cmds = ['ffmpeg', '-y', '-i', filename,
             "-q:v", "3", target_name]
     ffmpeg_cmd(cmds, get_length(filename), pb_prefix='Converting to mp4:')
     return target_name
 
+
 def convert_to_webm(filename, target_name=None, overwrite=False):
     """
     Converts a video to one with .webm extension using ffmpeg.
@@ -459,6 +469,8 @@ def convert_to_webm(filename, target_name=None, overwrite=False):
         return filename
     if not target_name:
         target_name = of + '.webm'
+    elif os.path.splitext(target_name)[1].lower() != '.webm':
+        raise WrongContainer(f"requested target container is NOT .webm but {os.path.splitext(target_name)[1]}.")
     if not overwrite:
         target_name = generate_outfilename(target_name)
     cmds = ['ffmpeg', '-y', '-i', filename,
@@ -486,6 +498,8 @@ def cast_into_avi(filename, target_name=None, overwrite=False):
     of = os.path.splitext(filename)[0]
     if not target_name:
         target_name = of + '.avi'
+    elif os.path.splitext(target_name)[1].lower() != '.avi':
+        raise WrongContainer(f"requested target container is NOT .avi but {os.path.splitext(target_name)[1]}.")
     if not overwrite:
         target_name = generate_outfilename(target_name)
     cmds = ['ffmpeg', '-y', '-i', filename, "-codec copy", target_name]

tests/test_utils.py

@@ -156,8 +156,8 @@ def test_output(self, format_pairs, execution_number, tmp_path, testvideo_avi):
         else:
             startfile = testvideo_avi
         result = convert(startfile, target_name)
-        length_in = get_length(startfile)
-        length_out = get_length(result)
+        # length_in = get_length(startfile)
+        # length_out = get_length(result)
         assert os.path.isfile(result) == True
         assert os.path.splitext(result)[1] == fex_to
         assert target_name == result
@@ -169,12 +169,17 @@ class Test_convert_to_avi:
     def test_output(self, tmp_path, testvideo_mp4):
         target_name = str(tmp_path).replace("\\", "/") + "/testvideo_converted.avi"
         testvideo_avi = convert_to_avi(testvideo_mp4, target_name=target_name)
-        length_in = get_length(testvideo_mp4)
-        length_out = get_length(testvideo_avi)
+        # length_in = get_length(testvideo_mp4)
+        # length_out = get_length(testvideo_avi)
         assert os.path.isfile(testvideo_avi) == True
         assert os.path.splitext(testvideo_avi)[1] == ".avi"
         assert target_name == testvideo_avi
         # assert length_in == length_out # this will fail due to ffmpeg bug: https://trac.ffmpeg.org/ticket/9443#ticket
+
+    def test_requested_container_incorrect(self, tmp_path, testvideo_mp4):
+        target_name = str(tmp_path).replace("\\", "/") + "/testvideo_converted.mp4"
+        with pytest.raises(WrongContainer):
+            convert_to_avi(testvideo_mp4, target_name=target_name)
 
 
 class Test_convert_to_mp4:
@@ -188,15 +193,25 @@ def test_output(self, tmp_path, testvideo_avi):
         assert target_name == testvideo_mp4
         assert length_in == length_out
 
+    def test_requested_container_incorrect(self, tmp_path, testvideo_avi):
+        target_name = str(tmp_path).replace("\\", "/") + "/testvideo_converted.avi"
+        with pytest.raises(WrongContainer):
+            convert_to_mp4(testvideo_avi, target_name=target_name)
+
 
 class Test_convert_to_webm:
     # @pytest.mark.xfail(raises=AssertionError)
     def test_output(self, tmp_path, testvideo_avi):
         target_name = str(tmp_path).replace("\\", "/") + "/testvideo_converted.webm"
         testvideo_webm = convert_to_webm(testvideo_avi, target_name=target_name)
-        length_in = get_length(testvideo_avi)
-        length_out = get_length(testvideo_webm)
+        # length_in = get_length(testvideo_avi)
+        # length_out = get_length(testvideo_webm)
         assert os.path.isfile(testvideo_webm) == True
         assert os.path.splitext(testvideo_webm)[1] == ".webm"
         assert target_name == testvideo_webm
-        # assert length_in == length_out # this will fail, need to find out why
+        # assert length_in == length_out # this will fail, need to find out why
+
+    def test_requested_container_incorrect(self, tmp_path, testvideo_avi):
+        target_name = str(tmp_path).replace("\\", "/") + "/testvideo_converted.mp4"
+        with pytest.raises(WrongContainer):
+            convert_to_webm(testvideo_avi, target_name=target_name)