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//! Use the Frame trait to remain generic over the number of channels at //! a single discrete moment in time. //! //! Implementations are provided for all fixed-size arrays up to 32 elements in length. use Sample; pub type Mono<S> = [S; 1]; pub type Stereo<S> = [S; 2]; /// Represents one sample from each channel at a single discrete instance in time within a /// PCM signal. /// /// We provide implementations for `Frame` for all fixed-size arrays up to a length of 32 elements. pub trait Frame: Copy + Clone + PartialEq { /// The type of PCM sample stored at each channel within the frame. type Sample: Sample; /// A typified version of a number of channels in the `Frame`, used for safely mapping frames /// of the same length to other `Frame`s, perhaps with a different `Sample` associated type. type NumChannels: NumChannels; /// An iterator yielding the sample in each channel, starting from left (channel 0) and ending /// at the right (channel NumChannels-1). type Channels: Iterator<Item = Self::Sample>; /// A frame type with equilavent number of channels using the associated `Sample::Signed` format. type Signed: Frame<Sample = <Self::Sample as Sample>::Signed, NumChannels = Self::NumChannels>; /// A frame type with equilavent number of channels using the associated `Sample::Float` format. type Float: Frame<Sample = <Self::Sample as Sample>::Float, NumChannels = Self::NumChannels>; /// The equilibrium value for the wave that this `Sample` type represents. This is normally the /// value that is equal distance from both the min and max ranges of the sample. /// /// **NOTE:** This will likely be changed to an "associated const" if the feature lands. /// /// # Examples /// /// ```rust /// extern crate sample; /// /// use sample::Frame; /// use sample::frame::{Mono, Stereo}; /// /// fn main() { /// assert_eq!(Mono::<f32>::equilibrium(), [0.0]); /// assert_eq!(Stereo::<f32>::equilibrium(), [0.0, 0.0]); /// assert_eq!(<[f32; 3]>::equilibrium(), [0.0, 0.0, 0.0]); /// assert_eq!(<[u8; 2]>::equilibrium(), [128u8, 128]); /// } /// ``` fn equilibrium() -> Self; /// Create a new `Frame` where the `Sample` for each channel is produced by the given function. /// /// The given function should map each channel index to its respective sample. fn from_fn<F>(from: F) -> Self where F: FnMut(usize) -> Self::Sample; /// Create a new `Frame` from a borrowed `Iterator` yielding samples for each channel. /// /// Returns `None` if the given `Iterator` does not yield enough `Sample`s. /// /// This is necessary for the `signal::FromSamples` `Iterator`, that converts some `Iterator` /// yielding `Sample`s to an `Iterator` yielding `Frame`s. fn from_samples<I>(samples: &mut I) -> Option<Self> where I: Iterator<Item = Self::Sample>; /// The total number of channels (and in turn samples) stored within the frame. fn n_channels() -> usize; /// Converts the frame into an iterator yielding the sample for each channel in the frame. fn channels(self) -> Self::Channels; /// Yields a reference to the `Sample` of the channel at the given index if there is one. fn channel(&self, idx: usize) -> Option<&Self::Sample>; /// Returns a pointer to the sample of the channel at the given index, without doing bounds /// checking. /// /// Note: This is primarily a necessity for efficient `Frame::map` and `Frame::zip_map` /// methods, as for those methods we can guarantee lengths of different `Frame`s to be the same /// at *compile-time*. unsafe fn channel_unchecked(&self, idx: usize) -> &Self::Sample; /// Applies the given function to each sample in the `Frame` in channel order and returns the /// result as a new `Frame`. /// /// # Example /// /// ```rust /// extern crate sample; /// /// use sample::{Frame, Sample}; /// /// fn main() { /// let foo = [0i16, 0]; /// let bar: [u8; 2] = foo.map(Sample::to_sample); /// assert_eq!(bar, [128u8, 128]); /// } /// ``` fn map<F, M>(self, map: M) -> F where F: Frame<NumChannels = Self::NumChannels>, M: FnMut(Self::Sample) -> F::Sample; /// Calls the given function with the pair of elements at every index and returns the /// resulting Frame. /// /// On a `Vec` this would be akin to `.into_iter().zip(other).map(|(a, b)| ...).collect()`, though /// much quicker and tailored to fixed-size arrays of samples. fn zip_map<O, F, M>(self, other: O, zip_map: M) -> F where O: Frame<NumChannels = Self::NumChannels>, F: Frame<NumChannels = Self::NumChannels>, M: FnMut(Self::Sample, O::Sample) -> F::Sample; /// Converts the frame type to the equivalent signal in its associated `Float`ing point format. /// /// # Example /// /// ```rust /// extern crate sample; /// /// use sample::Frame; /// /// fn main() { /// let foo = [128u8; 2]; /// let signed = foo.to_signed_frame(); /// assert_eq!(signed, [0i8; 2]); /// } /// ``` fn to_signed_frame(self) -> Self::Signed; /// Converts the frame type to the equivalent signal in its associated `Signed` format. /// /// # Example /// /// ```rust /// extern crate sample; /// /// use sample::Frame; /// /// fn main() { /// let foo = [128u8; 2]; /// let float = foo.to_float_frame(); /// assert_eq!(float, [0.0; 2]); /// } /// ``` fn to_float_frame(self) -> Self::Float; /// Offsets the amplitude of every channel in the frame by the given `offset` and yields the /// resulting frame. /// /// # Example /// /// ```rust /// extern crate sample; /// /// use sample::Frame; /// /// fn main() { /// assert_eq!([0.25, -0.5].offset_amp(0.5), [0.75, 0.0]); /// assert_eq!([0.5, -0.25].offset_amp(-0.25), [0.25, -0.5]); /// assert_eq!([128u8, 192].offset_amp(-64), [64, 128]); /// } /// ``` #[inline] fn offset_amp(self, offset: <Self::Sample as Sample>::Signed) -> Self { self.map(|s| s.add_amp(offset)) } /// Multiplies each `Sample` in the `Frame` by the given amplitude and returns the resulting /// `Frame`. /// /// - A > 1.0 amplifies the sample. /// - A < 1.0 attenuates the sample. /// - A == 1.0 yields the same sample. /// - A == 0.0 yields the `Sample::equilibrium`. /// /// # Example /// /// ```rust /// extern crate sample; /// /// use sample::Frame; /// /// fn main() { /// assert_eq!([0.1, 0.2, -0.1, -0.2].scale_amp(2.0), [0.2, 0.4, -0.2, -0.4]); /// } /// ``` #[inline] fn scale_amp(self, amp: <Self::Sample as Sample>::Float) -> Self { self.map(|s| s.mul_amp(amp)) } /// Sums each channel in `other` with each channel in `self` and returns the resulting `Frame`. /// /// # Example /// /// ```rust /// extern crate sample; /// /// use sample::Frame; /// /// fn main() { /// let foo = [0.25, 0.5].add_amp([-0.75, 0.25]); /// assert_eq!(foo, [-0.5, 0.75]); /// } /// ``` #[inline] fn add_amp<F>(self, other: F) -> Self where F: Frame<Sample = <Self::Sample as Sample>::Signed, NumChannels = Self::NumChannels>, { self.zip_map(other, Sample::add_amp) } /// Multiplies `other` with `self` and returns the resulting `Frame`. /// /// # Example /// /// ```rust /// extern crate sample; /// /// use sample::Frame; /// /// fn main() { /// let foo = [0.25, 0.4].mul_amp([0.2, 0.5]); /// assert_eq!(foo, [0.05, 0.2]); /// /// let bar = [192u8, 64].mul_amp([0.0, -2.0]); /// assert_eq!(bar, [128, 0]); /// } /// ``` #[inline] fn mul_amp<F>(self, other: F) -> Self where F: Frame<Sample = <Self::Sample as Sample>::Float, NumChannels = Self::NumChannels>, { self.zip_map(other, Sample::mul_amp) } } /// An iterator that yields the sample for each channel in the frame by value. #[derive(Clone)] pub struct Channels<F> { next_idx: usize, frame: F, } /// Restricts the types that may be used as the `Frame::NumChannels` associated type. /// /// `NumChannels` allows us to enforce the number of channels that a `Frame` must have in certain /// operations. This is particularly useful for `Frame::map` and `Frame::zip_map`, as it allows us /// to guarantee that the input and output frame types will retain the same number of channels at /// compile-time, and in turn removes the need for bounds checking. /// /// This trait is implemented for types `N1`...`N32`. pub trait NumChannels {} macro_rules! impl_frame { ($($NChan:ident $N:expr, [$($idx:expr)*],)*) => { $( /// A typified version of a number of channels. pub struct $NChan; impl NumChannels for $NChan {} impl<S> Frame for [S; $N] where S: Sample, { type Sample = S; type NumChannels = $NChan; type Channels = Channels<Self>; type Float = [S::Float; $N]; type Signed = [S::Signed; $N]; #[inline] fn equilibrium() -> Self { [S::equilibrium(); $N] } #[inline] fn n_channels() -> usize { $N } #[inline] fn channels(self) -> Self::Channels { Channels { next_idx: 0, frame: self, } } #[inline] fn channel(&self, idx: usize) -> Option<&Self::Sample> { self.get(idx) } #[inline] fn from_fn<F>(mut from: F) -> Self where F: FnMut(usize) -> S, { [$(from($idx), )*] } #[inline] fn from_samples<I>(samples: &mut I) -> Option<Self> where I: Iterator<Item=Self::Sample> { Some([$( { $idx; match samples.next() { Some(sample) => sample, None => return None, } }, )*]) } #[inline(always)] unsafe fn channel_unchecked(&self, idx: usize) -> &Self::Sample { self.get_unchecked(idx) } #[inline] fn to_signed_frame(self) -> Self::Signed { self.map(|s| s.to_sample()) } #[inline] fn to_float_frame(self) -> Self::Float { self.map(|s| s.to_sample()) } #[inline] fn map<F, M>(self, mut map: M) -> F where F: Frame<NumChannels=Self::NumChannels>, M: FnMut(Self::Sample) -> F::Sample, { F::from_fn(|channel_idx| { // Here we do not require run-time bounds checking as we have asserted that // the two arrays have the same number of channels at compile time with our // where clause, i.e. // // `F: Frame<NumChannels=Self::NumChannels>` unsafe { map(*self.channel_unchecked(channel_idx)) } }) } #[inline] fn zip_map<O, F, M>(self, other: O, mut zip_map: M) -> F where O: Frame<NumChannels=Self::NumChannels>, F: Frame<NumChannels=Self::NumChannels>, M: FnMut(Self::Sample, O::Sample) -> F::Sample { F::from_fn(|channel_idx| { // Here we do not require run-time bounds checking as we have asserted that the two // arrays have the same number of channels at compile time with our where clause, i.e. // // ``` // O: Frame<NumChannels=Self::NumChannels> // F: Frame<NumChannels=Self::NumChannels> // ``` unsafe { zip_map(*self.channel_unchecked(channel_idx), *other.channel_unchecked(channel_idx)) } }) } #[inline] fn scale_amp(self, amp: S::Float) -> Self { [$(self[$idx].mul_amp(amp), )*] } #[inline] fn add_amp<F>(self, other: F) -> Self where F: Frame<Sample=S::Signed, NumChannels=$NChan>, { // Here we do not require run-time bounds checking as we have asserted that the two // arrays have the same number of channels at compile time with our where clause, i.e. unsafe { [$(self[$idx].add_amp(*other.channel_unchecked($idx)), )*] } } } )* }; } impl_frame!{ N1 1, [0], N2 2, [0 1], N3 3, [0 1 2], N4 4, [0 1 2 3], N5 5, [0 1 2 3 4], N6 6, [0 1 2 3 4 5], N7 7, [0 1 2 3 4 5 6], N8 8, [0 1 2 3 4 5 6 7], N9 9, [0 1 2 3 4 5 6 7 8], N10 10, [0 1 2 3 4 5 6 7 8 9], N11 11, [0 1 2 3 4 5 6 7 8 9 10], N12 12, [0 1 2 3 4 5 6 7 8 9 10 11], N13 13, [0 1 2 3 4 5 6 7 8 9 10 11 12], N14 14, [0 1 2 3 4 5 6 7 8 9 10 11 12 13], N15 15, [0 1 2 3 4 5 6 7 8 9 10 11 12 13 14], N16 16, [0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15], N17 17, [0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16], N18 18, [0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17], N19 19, [0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18], N20 20, [0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19], N21 21, [0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20], N22 22, [0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21], N23 23, [0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22], N24 24, [0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23], N25 25, [0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24], N26 26, [0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25], N27 27, [0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26], N28 28, [0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27], N29 29, [0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28], N30 30, [0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29], N31 31, [0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30], N32 32, [0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31], } impl<F> Iterator for Channels<F> where F: Frame, { type Item = F::Sample; #[inline] fn next(&mut self) -> Option<Self::Item> { self.frame.channel(self.next_idx).map(|&s| s).map(|s| { self.next_idx += 1; s }) } } impl<F> ExactSizeIterator for Channels<F> where F: Frame, { #[inline] fn len(&self) -> usize { F::n_channels() - self.next_idx } }