From eecd4f657a896e6037e4796629ec3bfbb1530ccb Mon Sep 17 00:00:00 2001
From: Vincent Lostanlen <vincent.lostanlen@gmail.com>
Date: Fri, 16 Aug 2019 12:56:28 -0400
Subject: [PATCH] write transform function

---
 birdvoxpaint/birdvoxpaint.py | 76 ++++++++++++++++++++++++++++++++++++
 1 file changed, 76 insertions(+)
 create mode 100644 birdvoxpaint/birdvoxpaint.py

diff --git a/birdvoxpaint/birdvoxpaint.py b/birdvoxpaint/birdvoxpaint.py
new file mode 100644
index 0000000..83ced63
--- /dev/null
+++ b/birdvoxpaint/birdvoxpaint.py
@@ -0,0 +1,76 @@
+import librosa
+from librosa.util.exceptions.ParameterError
+import numpy as np
+
+
+def transform(filename=None, y=None, sr=22050,
+        n_fft=256, hop_length=32, frame_length=256, fmin=1000, fmax=10000,
+        indices=[average_energy], segment_duration=10,
+        verbose=False, n_jobs=-1):
+
+    if n_jobs=-1:
+        n_jobs = joblib.cpu_count()
+
+    if filename is not None:
+        if y is not None:
+            raise ParameterError(
+                'Either y or filename must be equal to None')
+        file_duration = librosa.get_duration(filename=filename)
+        orig_sr = librosa.get_samplerate(filename)
+        block_length = segment_duration * orig_sr * n_jobs
+        y_blocks = librosa.stream(filename, block_length=block_length,
+            frame_length=frame_length, hop_length=hop_length)
+        if sr is None:
+            sr = orig_sr
+    else:
+        if (y is None) or (sr is None):
+            raise ParameterError(
+                'At least one of (y, sr) or filename must be provided')
+        librosa.util.valid_audio(y, mono=True)
+        block_length = segment_duration * sr * n_jobs
+        file_duration = librosa.get_duration(y=y, sr=sr)
+        y_blocks = librosa.util.frame(y,
+            frame_length=block_length, hop_length=block_length)
+
+    if fmin < 0:
+        raise ParameterError("fmin={} must be nonnegative".format(fmin))
+
+    if fmax > (sr/2):
+        raise ParameterError(
+            "fmax={} must be smaller than sample rate sr={}".format(fmax, sr))
+
+    n_indices = len(indices)
+    n_blocks = int(np.ceil(file_duration / block_duration))
+    fft_frequencies = librosa.fft_frequencies(sr=sr, n_fft=n_fft)
+    bin_start = np.where(fft_frequencies>=fmin)[0][0]
+    bin_stop = np.where(fft_frequencies<fmax)[0][-1]
+    n_freqs = bin_stop - bin_start
+    feature_map = joblib.delayed(
+        lambda x: np.stack([feature_lambda(x) for feature_lambda in indices]))
+    joblib_parallel = joblib.Parallel(n_jobs=n_jobs)
+    X_list = []
+
+    for block_id in tqdm.tqdm(range(n_blocks), disable=not verbose):
+        if filename is not None:
+            y_block = next(y_blocks)
+            librosa.util.valid_audio(y_block, mono=True)
+            if sr!=orig_sr:
+                y_block = librosa.resample(y_block, orig_sr, sr)
+        else:
+            y_block = y_blocks[:, block_id]
+        S = librosa.stft(y_block, n_fft=n_fft,
+            hop_length=hop_length, win_length=frame_length, center=False)
+        truncated_length = (S_tensor.shape[1]//segment_length) * segment_length
+        if truncated_length == 0:
+            continue
+        else:
+            S = S[bin_start:bin_stop, :truncated_length]
+        S_tensor = np.reshape(S.T, (-1, segment_length, n_freqs)).T
+        n_segments = S_tensor.shape[2]
+        job_generator = (feature_map(S_tensor[:, :, segment_id])
+            for segment_id in range(n_segments))
+        X_list.append(np.stack(joblib_parallel(job_generator), axis=-1))
+
+    X_tensor = np.concatenate(X_list, axis=-1)
+
+    return X_tensor