Function write_temp_upload

app/server/runtime.cpp:158–177

Multipart file uploads arrive as in-memory bytes, but the WAV decoder only reads from disk, so uploaded audio is spooled to a uniquely named temp file before decoding.

        throw std::runtime_error("audio output sample rate must be positive");
    }
    if (audio.channels <= 0) {
        throw std::runtime_error("audio output channel count must be positive");
    }
    if (audio.samples.size() % static_cast<size_t>(audio.channels) != 0) {
        throw std::runtime_error("audio output sample count must be divisible by channel count");
    }

    std::vector<uint8_t> out;
    out.reserve(audio.samples.size() * sizeof(int16_t));
    auto append_bytes = [&](const void * data, size_t size) {
        const auto * bytes = static_cast<const uint8_t *>(data);
        out.insert(out.end(), bytes, bytes + size);
    };
    for (float sample : audio.samples) {
        sample = std::max(-1.0F, std::min(1.0F, sample));
        const auto pcm = static_cast<int16_t>(std::lrint(sample * 32767.0F));
        append_bytes(&pcm, sizeof(pcm));
    }
    return out;
}

std::string base64_encode(const uint8_t * data, size_t size) {
    constexpr char kAlphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";