Struct StreamingEncoder 

pub struct StreamingEncoder { /* private fields */ }

Streaming JPEG encoder configuration.

This encoder supports scanline-by-scanline encoding, which is memory-efficient for large images. It does NOT support trellis quantization, progressive mode, or Huffman optimization (these require buffering the entire image).

Use Encoder for full-featured batch encoding with optimizations.

Example

use mozjpeg_rs::Encoder;

// Create streaming encoder
let mut stream = Encoder::streaming()
    .quality(85)
    .start_rgb(1920, 1080, output_file)?;

// Write scanlines (must be in multiples of 8 or 16 depending on subsampling)
for chunk in rgb_scanlines.chunks(16 * 1920 * 3) {
    stream.write_scanlines(chunk)?;
}

// Finalize the JPEG
stream.finish()?;

Implementations

impl StreamingEncoder

pub fn new() -> StreamingEncoder

Create a new streaming encoder with default settings.

Unlike [Encoder::new()], this uses settings optimized for streaming:

• No trellis quantization (requires global context)
• No progressive mode (requires buffering entire image)
• No Huffman optimization (requires 2-pass)

pub fn quality(self, quality: u8) -> StreamingEncoder

Set quality level (1-100).

pub fn subsampling(self, mode: Subsampling) -> StreamingEncoder

Set chroma subsampling mode.

pub fn quant_tables(self, idx: QuantTableIdx) -> StreamingEncoder

Set quantization table variant.

pub fn force_baseline(self, enable: bool) -> StreamingEncoder

Force baseline-compatible output.

pub fn restart_interval(self, interval: u16) -> StreamingEncoder

Set restart interval in MCUs.

pub fn pixel_density(self, density: PixelDensity) -> StreamingEncoder

Set pixel density for the JFIF APP0 marker.

pub fn exif_data(self, data: Vec<u8>) -> StreamingEncoder

Set EXIF data to embed.

pub fn icc_profile(self, profile: Vec<u8>) -> StreamingEncoder

Set ICC color profile to embed.

pub fn add_marker(self, app_num: u8, data: Vec<u8>) -> StreamingEncoder

Add a custom APP marker.

pub fn custom_luma_qtable(self, table: [u16; 64]) -> StreamingEncoder

Set custom luminance quantization table.

pub fn custom_chroma_qtable(self, table: [u16; 64]) -> StreamingEncoder

Set custom chrominance quantization table.

pub fn start_rgb<W>( self, width: u32, height: u32, writer: W, ) -> Result<EncodingStream<W>, Error>

where W: Write,

Start streaming RGB encoding to a writer.

Arguments

• width - Image width in pixels
• height - Image height in pixels
• writer - Output writer

Returns

An EncodingStream that accepts scanlines.

pub fn start_gray<W>( self, width: u32, height: u32, writer: W, ) -> Result<EncodingStream<W>, Error>

where W: Write,

Start streaming grayscale encoding to a writer.

Arguments

• width - Image width in pixels
• height - Image height in pixels
• writer - Output writer

Returns

An EncodingStream that accepts scanlines.

Trait Implementations

impl Clone for StreamingEncoder

fn clone(&self) -> StreamingEncoder

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for StreamingEncoder

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Default for StreamingEncoder

fn default() -> StreamingEncoder

Returns the “default value” for a type.

impl Encode for StreamingEncoder

Implement batch encoding for StreamingEncoder (without optimizations).

fn encode_rgb( &self, rgb_data: &[u8], width: u32, height: u32, ) -> Result<Vec<u8>, Error>

Encode RGB image data to JPEG.

fn encode_gray( &self, gray_data: &[u8], width: u32, height: u32, ) -> Result<Vec<u8>, Error>

Encode grayscale image data to JPEG.