1 files changed, 86 insertions, 0 deletions
diff --git a/python/lib/aubio/slicing.py b/python/lib/aubio/slicing.py
new file mode 100644
index 0000000..fa9d2e3
--- /dev/null
+++ b/python/lib/aubio/slicing.py
@@ -0,0 +1,86 @@
+"""utility routines to slice sound files at given timestamps"""
+
+import os
+from aubio import source, sink
+
+_max_timestamp = 1e120
+
+def slice_source_at_stamps(source_file, timestamps, timestamps_end=None,
+                           output_dir=None, samplerate=0, hopsize=256):
+    """ slice a sound file at given timestamps """
+
+    if timestamps is None or len(timestamps) == 0:
+        raise ValueError("no timestamps given")
+
+    if timestamps[0] != 0:
+        timestamps = [0] + timestamps
+        if timestamps_end is not None:
+            timestamps_end = [timestamps[1] - 1] + timestamps_end
+
+    if timestamps_end is not None:
+        if len(timestamps_end) != len(timestamps):
+            raise ValueError("len(timestamps_end) != len(timestamps)")
+    else:
+        timestamps_end = [t - 1 for t in timestamps[1:]] + [_max_timestamp]
+
+    regions = list(zip(timestamps, timestamps_end))
+    #print regions
+
+    source_base_name, _ = os.path.splitext(os.path.basename(source_file))
+    if output_dir is not None:
+        if not os.path.isdir(output_dir):
+            os.makedirs(output_dir)
+        source_base_name = os.path.join(output_dir, source_base_name)
+
+    def new_sink_name(source_base_name, timestamp, samplerate):
+        """ create a sink based on a timestamp in samples, converted in seconds """
+        timestamp_seconds = timestamp / float(samplerate)
+        return source_base_name + "_%011.6f" % timestamp_seconds + '.wav'
+
+    # open source file
+    _source = source(source_file, samplerate, hopsize)
+    samplerate = _source.samplerate
+
+    total_frames = 0
+    slices = []
+
+    while True:
+        # get hopsize new samples from source
+        vec, read = _source.do_multi()
+        # if the total number of frames read will exceed the next region start
+        if len(regions) and total_frames + read >= regions[0][0]:
+            #print "getting", regions[0], "at", total_frames
+            # get next region
+            start_stamp, end_stamp = regions.pop(0)
+            # create a name for the sink
+            new_sink_path = new_sink_name(source_base_name, start_stamp, samplerate)
+            # create its sink
+            _sink = sink(new_sink_path, samplerate, _source.channels)
+            # create a dictionary containing all this
+            new_slice = {'start_stamp': start_stamp, 'end_stamp': end_stamp, 'sink': _sink}
+            # append the dictionary to the current list of slices
+            slices.append(new_slice)
+
+        for current_slice in slices:
+            start_stamp = current_slice['start_stamp']
+            end_stamp = current_slice['end_stamp']
+            _sink = current_slice['sink']
+            # sample index to start writing from new source vector
+            start = max(start_stamp - total_frames, 0)
+            # number of samples yet to written be until end of region
+            remaining = end_stamp - total_frames + 1
+            #print current_slice, remaining, start
+            # not enough frames remaining, time to split
+            if remaining < read:
+                if remaining > start:
+                    # write remaining samples from current region
+                    _sink.do_multi(vec[:, start:remaining], remaining - start)
+                    #print "closing region", "remaining", remaining
+                    # close this file
+                    _sink.close()
+            elif read > start:
+                # write all the samples
+                _sink.do_multi(vec[:, start:read], read - start)
+        total_frames += read
+        if read < hopsize:
+            break