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lms/src/libs/audio/impl/musicnn/MusicNNEmbeddings.cpp
T

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C++

/*
* Copyright (C) 2026 Emeric Poupon
*
* This file is part of LMS.
*
* LMS is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* LMS is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with LMS. If not, see <http://www.gnu.org/licenses/>.
*/
#include "audio/MusicNNEmbeddings.hpp"
#include <bit>
#include <cstring>
#include <limits>
#include "audio/Exception.hpp"
namespace lms::audio
{
static_assert(sizeof(float) == 4);
static_assert(std::numeric_limits<float>::is_iec559);
namespace
{
constexpr uint32_t byteswap32(uint32_t x)
{
return (x >> 24) | ((x >> 8) & 0x0000FF00u) | ((x << 8) & 0x00FF0000u) | (x << 24);
}
void writeFloats(std::span<const float> data, std::span<std::byte> blob)
{
if (blob.size() < data.size() * sizeof(uint32_t))
throw Exception{ "Buffer too small to write MusicNN embeddings" };
for (std::size_t i{}; i < data.size(); ++i)
{
uint32_t bits{ std::bit_cast<uint32_t>(data[i]) };
if constexpr (std::endian::native == std::endian::little)
bits = byteswap32(bits);
std::memcpy(blob.data() + i * 4, &bits, 4);
}
}
void readFloats(std::span<const std::byte> blob, std::span<float> data)
{
if (blob.size() < data.size() * sizeof(uint32_t))
throw Exception{ "Buffer too small to read MusicNN embeddings" };
for (std::size_t i{}; i < data.size(); ++i)
{
uint32_t bits{};
std::memcpy(&bits, blob.data() + i * 4, 4);
if constexpr (std::endian::native == std::endian::little)
bits = byteswap32(bits);
data[i] = std::bit_cast<float>(bits);
}
}
} // anonymous namespace
void trackMusicNNEmbeddingsToBlob(const TrackMusicNNEmbeddings& embeddings, std::span<std::byte> buffer)
{
if (buffer.size() < sizeof(TrackMusicNNEmbeddings))
throw Exception{ "Buffer too small to write TrackMusicNNEmbeddings" };
writeFloats(embeddings.mean.values, buffer.subspan(0, MusicNNEmbedding::size * sizeof(float)));
}
void trackMusicNNEmbeddingsFromBlob(std::span<const std::byte> buffer, TrackMusicNNEmbeddings& embeddings)
{
if (buffer.size() < sizeof(TrackMusicNNEmbeddings))
throw Exception{ "Buffer too small to read TrackMusicNNEmbeddings" };
readFloats(buffer.subspan(0, MusicNNEmbedding::size * sizeof(float)), embeddings.mean.values);
}
} // namespace lms::audio