MusicGen / audiocraft /metrics /chroma_cosinesim.py
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# Copyright (c) Meta Platforms, Inc. and affiliates.
# All rights reserved.
#
# This source code is licensed under the license found in the
# LICENSE file in the root directory of this source tree.
import torch
import torchmetrics
from ..data.audio_utils import convert_audio
from ..modules.chroma import ChromaExtractor
class ChromaCosineSimilarityMetric(torchmetrics.Metric):
"""Chroma cosine similarity metric.
This metric extracts a chromagram for a reference waveform and
a generated waveform and compares each frame using the cosine similarity
function. The output is the mean cosine similarity.
Args:
sample_rate (int): Sample rate used by the chroma extractor.
n_chroma (int): Number of chroma used by the chroma extractor.
radix2_exp (int): Exponent for the chroma extractor.
argmax (bool): Whether the chroma extractor uses argmax.
eps (float): Epsilon for cosine similarity computation.
"""
def __init__(self, sample_rate: int, n_chroma: int, radix2_exp: int, argmax: bool, eps: float = 1e-8):
super().__init__()
self.chroma_sample_rate = sample_rate
self.n_chroma = n_chroma
self.eps = eps
self.chroma_extractor = ChromaExtractor(sample_rate=self.chroma_sample_rate, n_chroma=self.n_chroma,
radix2_exp=radix2_exp, argmax=argmax)
self.add_state("cosine_sum", default=torch.tensor(0.), dist_reduce_fx="sum")
self.add_state("weight", default=torch.tensor(0.), dist_reduce_fx="sum")
def update(self, preds: torch.Tensor, targets: torch.Tensor,
sizes: torch.Tensor, sample_rates: torch.Tensor) -> None:
"""Compute cosine similarity between chromagrams and accumulate scores over the dataset."""
if preds.size(0) == 0:
return
assert preds.shape == targets.shape, (
f"Preds and target shapes mismatch: preds={preds.shape}, targets={targets.shape}")
assert preds.size(0) == sizes.size(0), (
f"Number of items in preds ({preds.shape}) mismatch ",
f"with sizes ({sizes.shape})")
assert preds.size(0) == sample_rates.size(0), (
f"Number of items in preds ({preds.shape}) mismatch ",
f"with sample_rates ({sample_rates.shape})")
assert torch.all(sample_rates == sample_rates[0].item()), "All sample rates are not the same in the batch"
device = self.weight.device
preds, targets = preds.to(device), targets.to(device) # type: ignore
sample_rate = sample_rates[0].item()
preds = convert_audio(preds, from_rate=sample_rate, to_rate=self.chroma_sample_rate, to_channels=1)
targets = convert_audio(targets, from_rate=sample_rate, to_rate=self.chroma_sample_rate, to_channels=1)
gt_chroma = self.chroma_extractor(targets)
gen_chroma = self.chroma_extractor(preds)
chroma_lens = (sizes / self.chroma_extractor.winhop).ceil().int()
for i in range(len(gt_chroma)):
t = int(chroma_lens[i].item())
cosine_sim = torch.nn.functional.cosine_similarity(
gt_chroma[i, :t], gen_chroma[i, :t], dim=1, eps=self.eps)
self.cosine_sum += cosine_sim.sum(dim=0) # type: ignore
self.weight += torch.tensor(t) # type: ignore
def compute(self) -> float:
"""Computes the average cosine similarty across all generated/target chromagrams pairs."""
assert self.weight.item() > 0, "Unable to compute with total number of comparisons <= 0" # type: ignore
return (self.cosine_sum / self.weight).item() # type: ignore