Class Sample

src/fl/audio/audio.h:22–63

Sample is a wrapper around SampleImpl, hiding the reference counting so that the api object can be simple and have standard object semantics.

// counting so that the api object can be simple and have standard object
// semantics.
class Sample {
  public:
    using VectorPCM = fl::vector<fl::i16>;
    using const_iterator = VectorPCM::const_iterator;
    Sample() FL_NOEXCEPT {}
    Sample(const Sample &other) FL_NOEXCEPT : mImpl(other.mImpl) {}
    Sample(SampleImplPtr impl) FL_NOEXCEPT : mImpl(impl) {}
    ~Sample() FL_NOEXCEPT;

    // Constructor that takes raw audio data and handles pooling internally
    Sample(fl::span<const fl::i16> span, fl::u32 timestamp = 0) FL_NOEXCEPT;

    Sample &operator=(const Sample &other) FL_NOEXCEPT;
    bool isValid() const FL_NOEXCEPT { return mImpl != nullptr; }

    fl::size size() const FL_NOEXCEPT;
    // Raw pcm levels.
    const VectorPCM &pcm() const FL_NOEXCEPT;
    // Zero crossing factor between 0.0f -> 1.0f, detects "hiss"
    // and sounds like cloths rubbing. Useful for sound analysis.
    float zcf() const FL_NOEXCEPT;
    float rms() const FL_NOEXCEPT;
    fl::u32 timestamp() const FL_NOEXCEPT;  // Timestamp when sample became valid (millis)

    void fft(fft::Bins *out) const FL_NOEXCEPT;

    const_iterator begin() const FL_NOEXCEPT { return pcm().begin(); }
    const_iterator end() const FL_NOEXCEPT { return pcm().end(); }
    const fl::i16 &at(fl::size i) const FL_NOEXCEPT;
    const fl::i16 &operator[](fl::size i) const FL_NOEXCEPT;
    operator bool() const FL_NOEXCEPT { return isValid(); }
    bool operator==(const Sample &other) const FL_NOEXCEPT;
    bool operator!=(const Sample &other) const FL_NOEXCEPT;

    /// Apply a digital gain multiplier to all PCM samples in-place.
    /// Clamps to i16 range to prevent overflow.
    void applyGain(float gain) FL_NOEXCEPT;

  private:
    static const VectorPCM &empty() FL_NOEXCEPT;
    SampleImplPtr mImpl;
};

// Sound level meter is a persistant measuring class that will auto-tune the
// microphone to real world SPL levels. It will adapt to the noise floor of the