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librosa.to_stereo

librosa.to_stereo(*, left, right, downmix=True, pad=True, norm=True, out=None)

Combine two signals into a stereo signal.

Parameters:

leftnp.ndarray [shape=(…, n)] or None

Left channel signal. Multi-channel is supported.

rightnp.ndarray [shape=(…, m)] or None

Right channel signal. Multi-channel is supported.

downmixbool

If True, downmix the left and right channels to mono before combining.

If False, the left and right signals are additively combined.

padbool

If True, pad the shorter channel with zeros to match the length of the longer channel. If False, the longer channel is trimmed to match the length of the shorter channel.

normbool

If True (default), signals are combined by averaging.

If False, signals are combined by summing.

outnp.ndarray [shape=(2, n_out)] or None

A pre-allocated output buffer. If provided, it must match the shape (2, n_out), and its dtype must be at least as precise as the result dtype; it is zeroed and filled in place and returned, avoiding a new allocation. If None (default), a new array is allocated.

Returns:

y_stereonp.ndarray [shape=(2, n_out)]

Stereo signal with left channel in the first row and right channel in the second row. If out was provided, this is the same object as out.

See also

to_mono

to_multi

util.fix_length

Notes

At least one of left or right must be provided.

Examples

Combine two mono signals into a hard-panned stereo signal

>>> y1 = librosa.tone(440.0, sr=22050, duration=1.0)
>>> y2 = librosa.tone(550.0, sr=22050, duration=1.0)
>>> y_stereo = librosa.to_stereo(left=y1, right=y2)

Upmix a mono signal into the left or right channel in stereo

>>> y_left = librosa.to_stereo(left=y1, right=None)
>>> y_right = librosa.to_stereo(left=None, right=y2)

Downmix a stereo signal into the left channel, and mix a third mono signal into the right channel

>>> y3 = librosa.tone(660.0, sr=22050, duration=1.0)
>>> y_mix = librosa.to_stereo(left=y_stereo, right=y3, downmix=True)

Keep the original stereo signal separated, but mix a third signal into the right channel:

>>> y_mix = librosa.to_stereo(left=y_stereo, right=y3, downmix=False)