1//! Encoding of AVIF images.
2///
3/// The [AVIF] specification defines an image derivative of the AV1 bitstream, an open video codec.
4///
5/// [AVIF]: https://aomediacodec.github.io/av1-avif/
6use std::borrow::Cow;
7use std::cmp::min;
8use std::io::Write;
9use std::mem::size_of;
10
11use crate::buffer::ConvertBuffer;
12use crate::color::{FromColor, Luma, LumaA, Rgb, Rgba};
13use crate::error::{
14 EncodingError, ParameterError, ParameterErrorKind, UnsupportedError, UnsupportedErrorKind,
15};
16use crate::{ExtendedColorType, ImageBuffer, ImageEncoder, ImageFormat, Pixel};
17use crate::{ImageError, ImageResult};
18
19use bytemuck::{try_cast_slice, try_cast_slice_mut, Pod, PodCastError};
20use num_traits::Zero;
21use ravif::{Encoder, Img, RGB8, RGBA8};
22use rgb::AsPixels;
23
24/// AVIF Encoder.
25///
26/// Writes one image into the chosen output.
27pub struct AvifEncoder<W> {
28 inner: W,
29 encoder: Encoder,
30}
31
32/// An enumeration over supported AVIF color spaces
33#[derive(Debug, Copy, Clone, PartialEq, Eq)]
34#[non_exhaustive]
35pub enum ColorSpace {
36 /// sRGB colorspace
37 Srgb,
38 /// BT.709 colorspace
39 Bt709,
40}
41
42impl ColorSpace {
43 fn to_ravif(self) -> ravif::ColorSpace {
44 match self {
45 Self::Srgb => ravif::ColorSpace::RGB,
46 Self::Bt709 => ravif::ColorSpace::YCbCr,
47 }
48 }
49}
50
51enum RgbColor<'buf> {
52 Rgb8(Img<&'buf [RGB8]>),
53 Rgba8(Img<&'buf [RGBA8]>),
54}
55
56impl<W: Write> AvifEncoder<W> {
57 /// Create a new encoder that writes its output to `w`.
58 pub fn new(w: W) -> Self {
59 AvifEncoder::new_with_speed_quality(w, 4, 80) // `cavif` uses these defaults
60 }
61
62 /// Create a new encoder with a specified speed and quality that writes its output to `w`.
63 /// `speed` accepts a value in the range 1-10, where 1 is the slowest and 10 is the fastest.
64 /// Slower speeds generally yield better compression results.
65 /// `quality` accepts a value in the range 1-100, where 1 is the worst and 100 is the best.
66 pub fn new_with_speed_quality(w: W, speed: u8, quality: u8) -> Self {
67 // Clamp quality and speed to range
68 let quality = min(quality, 100);
69 let speed = min(speed, 10);
70
71 let encoder = Encoder::new()
72 .with_quality(f32::from(quality))
73 .with_alpha_quality(f32::from(quality))
74 .with_speed(speed)
75 .with_depth(Some(8));
76
77 AvifEncoder { inner: w, encoder }
78 }
79
80 /// Encode with the specified `color_space`.
81 pub fn with_colorspace(mut self, color_space: ColorSpace) -> Self {
82 self.encoder = self
83 .encoder
84 .with_internal_color_space(color_space.to_ravif());
85 self
86 }
87
88 /// Configures `rayon` thread pool size.
89 /// The default `None` is to use all threads in the default `rayon` thread pool.
90 pub fn with_num_threads(mut self, num_threads: Option<usize>) -> Self {
91 self.encoder = self.encoder.with_num_threads(num_threads);
92 self
93 }
94}
95
96impl<W: Write> ImageEncoder for AvifEncoder<W> {
97 /// Encode image data with the indicated color type.
98 ///
99 /// The encoder currently requires all data to be RGBA8, it will be converted internally if
100 /// necessary. When data is suitably aligned, i.e. u16 channels to two bytes, then the
101 /// conversion may be more efficient.
102 #[track_caller]
103 fn write_image(
104 mut self,
105 data: &[u8],
106 width: u32,
107 height: u32,
108 color: ExtendedColorType,
109 ) -> ImageResult<()> {
110 let expected_buffer_len = color.buffer_size(width, height);
111 assert_eq!(
112 expected_buffer_len,
113 data.len() as u64,
114 "Invalid buffer length: expected {expected_buffer_len} got {} for {width}x{height} image",
115 data.len(),
116 );
117
118 self.set_color(color);
119 // `ravif` needs strongly typed data so let's convert. We can either use a temporarily
120 // owned version in our own buffer or zero-copy if possible by using the input buffer.
121 // This requires going through `rgb`.
122 let mut fallback = vec![]; // This vector is used if we need to do a color conversion.
123 let result = match Self::encode_as_img(&mut fallback, data, width, height, color)? {
124 RgbColor::Rgb8(buffer) => self.encoder.encode_rgb(buffer),
125 RgbColor::Rgba8(buffer) => self.encoder.encode_rgba(buffer),
126 };
127 let data = result.map_err(|err| {
128 ImageError::Encoding(EncodingError::new(ImageFormat::Avif.into(), err))
129 })?;
130 self.inner.write_all(&data.avif_file)?;
131 Ok(())
132 }
133}
134
135impl<W: Write> AvifEncoder<W> {
136 // Does not currently do anything. Mirrors behaviour of old config function.
137 fn set_color(&mut self, _color: ExtendedColorType) {
138 // self.config.color_space = ColorSpace::RGB;
139 }
140
141 fn encode_as_img<'buf>(
142 fallback: &'buf mut Vec<u8>,
143 data: &'buf [u8],
144 width: u32,
145 height: u32,
146 color: ExtendedColorType,
147 ) -> ImageResult<RgbColor<'buf>> {
148 // Error wrapping utility for color dependent buffer dimensions.
149 fn try_from_raw<P: Pixel + 'static>(
150 data: &[P::Subpixel],
151 width: u32,
152 height: u32,
153 ) -> ImageResult<ImageBuffer<P, &[P::Subpixel]>> {
154 ImageBuffer::from_raw(width, height, data).ok_or_else(|| {
155 ImageError::Parameter(ParameterError::from_kind(
156 ParameterErrorKind::DimensionMismatch,
157 ))
158 })
159 }
160
161 // Convert to target color type using few buffer allocations.
162 fn convert_into<'buf, P>(
163 buf: &'buf mut Vec<u8>,
164 image: ImageBuffer<P, &[P::Subpixel]>,
165 ) -> Img<&'buf [RGBA8]>
166 where
167 P: Pixel + 'static,
168 Rgba<u8>: FromColor<P>,
169 {
170 let (width, height) = image.dimensions();
171 // TODO: conversion re-using the target buffer?
172 let image: ImageBuffer<Rgba<u8>, _> = image.convert();
173 *buf = image.into_raw();
174 Img::new(buf.as_pixels(), width as usize, height as usize)
175 }
176
177 // Cast the input slice using few buffer allocations if possible.
178 // In particular try not to allocate if the caller did the infallible reverse.
179 fn cast_buffer<Channel>(buf: &[u8]) -> ImageResult<Cow<[Channel]>>
180 where
181 Channel: Pod + Zero,
182 {
183 match try_cast_slice(buf) {
184 Ok(slice) => Ok(Cow::Borrowed(slice)),
185 Err(PodCastError::OutputSliceWouldHaveSlop) => Err(ImageError::Parameter(
186 ParameterError::from_kind(ParameterErrorKind::DimensionMismatch),
187 )),
188 Err(PodCastError::TargetAlignmentGreaterAndInputNotAligned) => {
189 // Sad, but let's allocate.
190 // bytemuck checks alignment _before_ slop but size mismatch before this..
191 if buf.len() % size_of::<Channel>() != 0 {
192 Err(ImageError::Parameter(ParameterError::from_kind(
193 ParameterErrorKind::DimensionMismatch,
194 )))
195 } else {
196 let len = buf.len() / size_of::<Channel>();
197 let mut data = vec![Channel::zero(); len];
198 let view = try_cast_slice_mut::<_, u8>(data.as_mut_slice()).unwrap();
199 view.copy_from_slice(buf);
200 Ok(Cow::Owned(data))
201 }
202 }
203 Err(err) => {
204 // Are you trying to encode a ZST??
205 Err(ImageError::Parameter(ParameterError::from_kind(
206 ParameterErrorKind::Generic(format!("{err:?}")),
207 )))
208 }
209 }
210 }
211
212 match color {
213 ExtendedColorType::Rgb8 => {
214 // ravif doesn't do any checks but has some asserts, so we do the checks.
215 let img = try_from_raw::<Rgb<u8>>(data, width, height)?;
216 // Now, internally ravif uses u32 but it takes usize. We could do some checked
217 // conversion but instead we use that a non-empty image must be addressable.
218 if img.pixels().len() == 0 {
219 return Err(ImageError::Parameter(ParameterError::from_kind(
220 ParameterErrorKind::DimensionMismatch,
221 )));
222 }
223
224 Ok(RgbColor::Rgb8(Img::new(
225 AsPixels::as_pixels(data),
226 width as usize,
227 height as usize,
228 )))
229 }
230 ExtendedColorType::Rgba8 => {
231 // ravif doesn't do any checks but has some asserts, so we do the checks.
232 let img = try_from_raw::<Rgba<u8>>(data, width, height)?;
233 // Now, internally ravif uses u32 but it takes usize. We could do some checked
234 // conversion but instead we use that a non-empty image must be addressable.
235 if img.pixels().len() == 0 {
236 return Err(ImageError::Parameter(ParameterError::from_kind(
237 ParameterErrorKind::DimensionMismatch,
238 )));
239 }
240
241 Ok(RgbColor::Rgba8(Img::new(
242 AsPixels::as_pixels(data),
243 width as usize,
244 height as usize,
245 )))
246 }
247 // we need a separate buffer..
248 ExtendedColorType::L8 => {
249 let image = try_from_raw::<Luma<u8>>(data, width, height)?;
250 Ok(RgbColor::Rgba8(convert_into(fallback, image)))
251 }
252 ExtendedColorType::La8 => {
253 let image = try_from_raw::<LumaA<u8>>(data, width, height)?;
254 Ok(RgbColor::Rgba8(convert_into(fallback, image)))
255 }
256 // we need to really convert data..
257 ExtendedColorType::L16 => {
258 let buffer = cast_buffer(data)?;
259 let image = try_from_raw::<Luma<u16>>(&buffer, width, height)?;
260 Ok(RgbColor::Rgba8(convert_into(fallback, image)))
261 }
262 ExtendedColorType::La16 => {
263 let buffer = cast_buffer(data)?;
264 let image = try_from_raw::<LumaA<u16>>(&buffer, width, height)?;
265 Ok(RgbColor::Rgba8(convert_into(fallback, image)))
266 }
267 ExtendedColorType::Rgb16 => {
268 let buffer = cast_buffer(data)?;
269 let image = try_from_raw::<Rgb<u16>>(&buffer, width, height)?;
270 Ok(RgbColor::Rgba8(convert_into(fallback, image)))
271 }
272 ExtendedColorType::Rgba16 => {
273 let buffer = cast_buffer(data)?;
274 let image = try_from_raw::<Rgba<u16>>(&buffer, width, height)?;
275 Ok(RgbColor::Rgba8(convert_into(fallback, image)))
276 }
277 // for cases we do not support at all?
278 _ => Err(ImageError::Unsupported(
279 UnsupportedError::from_format_and_kind(
280 ImageFormat::Avif.into(),
281 UnsupportedErrorKind::Color(color),
282 ),
283 )),
284 }
285 }
286}
287