Use embedded loop tags as the first choice and add a lossless trim command

.github/workflows/tests.yml

@@ -0,0 +1,25 @@
+name: Tests
+
+on:
+  push:
+  pull_request:
+
+permissions:
+  contents: read
+
+jobs:
+  test:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, windows-latest]
+        python-version: ["3.10", "3.13"]
+    steps:
+    - uses: actions/checkout@v4
+    - name: Set up uv
+      uses: astral-sh/setup-uv@v6
+      with:
+        python-version: ${{ matrix.python-version }}
+    - name: Run tests
+      run: uv run pytest

README.md

@@ -119,6 +119,8 @@ pymusiclooper -i play --url "https://www.youtube.com/watch?v=dQw4w9WgXcQ"
 pymusiclooper play-tagged --path "TRACK_NAME.mp3" --tag-names LOOP_START LOOP_END
 ```
 
+*Note: if a file already has loop metadata tags (e.g. LOOP_START/LOOP_END or LOOPSTART/LOOPLENGTH), they are used as the first loop choice by all commands. Use `--ignore-tags` to skip them.*
+
 ### Export
 
 *Note: batch processing is available for all export subcommands. Simply specify a directory instead of a file as the path to be used.*
@@ -145,6 +147,10 @@ pymusiclooper export-points --path "/path/to/track.wav" --alt-export-top -1
 # (or all audio files in a directory, if a directory path is used instead)
 pymusiclooper -i tag --path "TRACK_NAME.mp3" --tag-names LOOP_START LOOP_END
 
+# Losslessly cut everything after the loop end (WAV, FLAC and OGG Vorbis only), keeping 1000 samples past it
+# The original format, bit depth and tags are preserved; OGG files are cut without re-encoding
+pymusiclooper -i trim --path "TRACK_NAME.wav" --keep-after 1000
+
 
 # Export the loop points (in samples) of all tracks in a particular directory to a loops.txt file
 # (compatible with https://github.com/libertyernie/LoopingAudioConverter/)

pymusiclooper/analysis.py

@@ -20,6 +20,7 @@ class LoopPair:
         note_distance: float
         loudness_difference: float
         score: float. Defaults to 0.
+        from_metadata: bool (loop points were read from the file's metadata tags instead of being detected). Defaults to False.
     """
 
     _loop_start_frame_idx: int
@@ -29,6 +30,7 @@ class LoopPair:
     score: float = 0
     loop_start: int = 0
     loop_end: int = 0
+    from_metadata: bool = False
 
 
 def find_best_loop_points(
@@ -172,10 +174,6 @@ def find_best_loop_points(
         mlaudio, chroma, bpm, candidate_pairs, disable_pruning
     )
 
-    # prefer longer loops for highly similar sequences
-    if len(filtered_candidate_pairs) > 1:
-        _prioritize_duration(filtered_candidate_pairs)
-
     # Set the exact loop start and end in samples and adjust them
     # to the nearest zero crossing. Avoids audio popping/clicking while looping
     # as much as possible.
@@ -203,6 +201,11 @@ def find_best_loop_points(
             f"No loop points found for {mlaudio.filename} with current parameters."
         )
 
+    # prefer longer loops for highly similar sequences
+    # (must run after the loop positions in samples are set, since it compares loop durations)
+    if len(filtered_candidate_pairs) > 1:
+        _prioritize_duration(filtered_candidate_pairs)
+
     logging.info(
         f"Filtered to {len(filtered_candidate_pairs)} best candidate loop points"
     )
@@ -522,8 +525,12 @@ def _calculate_subseq_beat_similarity(
     cosine_sim = dot_prod / (np.maximum(b1_norm * b2_norm, 1e-10))
 
     if max_offset < test_length:
+        # Pad the missing frames on the side farthest from the loop point:
+        # after the tested frames when looking ahead, before them when looking behind
+        missing_frames = test_length - max_offset
+        pad_width = (missing_frames, 0) if test_end_offset < 0 else (0, missing_frames)
         return np.average(
-            np.pad(cosine_sim, pad_width=(0, test_length - max_offset), mode="constant", constant_values=0),
+            np.pad(cosine_sim, pad_width=pad_width, mode="constant", constant_values=0),
             weights=weights,
         )
     else:

pymusiclooper/audio.py

@@ -48,7 +48,8 @@ def __init__(self, filepath: str) -> None:
             raise AudioLoadError(f"\"{filepath}\" only contains silence and cannot be analyzed.")
 
         # Normalize audio channels to between -1.0 and +1.0 before analysis
-        mono_signal /= np.max(np.abs(mono_signal))
+        # (not in-place: for mono input, to_mono returns raw_audio itself, which is also used for playback/export)
+        mono_signal = mono_signal / np.max(np.abs(mono_signal))
 
         self.audio, self.trim_offset = librosa.effects.trim(mono_signal, top_db=40)
         self.trim_offset = self.trim_offset[0]

pymusiclooper/cli.py

@@ -77,6 +77,7 @@ def common_loop_options(f):
     @click.option('--approx-loop-position', type=click.FloatRange(min=0), nargs=2, default=None, help='The approximate desired loop start and loop end in seconds. [dim]([cyan]+/-2[/] second search window for each point)[/]')
     @click.option("--brute-force", is_flag=True, default=False, help=r"Check the entire audio track instead of just the detected beats. [dim yellow](Warning: may take several minutes to complete.)[/]")
     @click.option("--disable-pruning", is_flag=True, default=False, help="Disables filtering of the detected loop points from the initial pass.")
+    @click.option("--ignore-tags", is_flag=True, default=False, help="Ignore loop points already stored in the file's metadata tags (e.g. LOOP_START/LOOP_END), which are otherwise used as the first choice.")
 
     @functools.wraps(f)
     def wrapper_common_options(*args, **kwargs):
@@ -123,12 +124,13 @@ def play(**kwargs):
         start_time = handler.format_time(chosen_loop_pair.loop_start, in_samples=in_samples)
         end_time = handler.format_time(chosen_loop_pair.loop_end, in_samples=in_samples)
 
+        source = (
+            "loop points from metadata tags"
+            if chosen_loop_pair.from_metadata
+            else f"similarity: {chosen_loop_pair.score:.2%}"
+        )
         rich_console.print(
-            "\nPlaying with looping active from [green]{}[/] back to [green]{}[/]; similarity: {:.2%}".format(
-                end_time,
-                start_time,
-                chosen_loop_pair.score,
-            )
+            f"\nPlaying with looping active from [green]{end_time}[/] back to [green]{start_time}[/]; {source}"
         )
         rich_console.print("(Press [red]Ctrl+C[/] to stop looping.)")
 
@@ -226,6 +228,17 @@ def tag(**kwargs):
     run_handler(**kwargs)
 
 
+@cli_main.command()
+@common_path_options
+@common_loop_options
+@common_export_options
+@click.option('--keep-after', type=click.IntRange(min=0), default=0, show_default=True, help="Number of samples to keep after the loop end.")
+def trim(**kwargs):
+    """Losslessly cut the audio after the loop end, keeping its original format, bit depth and tags. [dim](WAV, FLAC and OGG Vorbis only)[/]"""
+    kwargs["trim"] = True
+    run_handler(**kwargs)
+
+
 def run_handler(**kwargs):
     try:
         if kwargs.get("url", None) is not None:

pymusiclooper/console.py

@@ -12,6 +12,7 @@
     "--approx-loop-position",
     "--brute-force",
     "--disable-pruning",
+    "--ignore-tags",
 ]
 _export_options = ["--output-dir", "--format"]
 _batch_options = ["--recursive", "--flatten"]
@@ -49,6 +50,7 @@ def _option_groups(additional_basic_options=None):
     "pymusiclooper tag": _option_groups(["--tag-names", "--tag-offset"]),
     "pymusiclooper export-points": _option_groups(["--export-to", "--alt-export-top", "--fmt"]),
     "pymusiclooper extend": _option_groups(["--extended-length", "--fade-length", "--disable-fade-out"]),
+    "pymusiclooper trim": _option_groups(["--keep-after"]),
 }
 _COMMAND_GROUPS = {
     "pymusiclooper": [
@@ -66,6 +68,7 @@ def _option_groups(additional_basic_options=None):
                 "split-audio",
                 "tag",
                 "extend",
+                "trim",
             ],
         }
     ]