347 lines
13 KiB
Rust
347 lines
13 KiB
Rust
use alloc::borrow::ToOwned;
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use alloc::vec;
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use alloc::vec::Vec;
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use core::iter;
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use std::io::Read;
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use crate::read_u8;
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use crate::error::{Error, Result};
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use crate::marker::Marker;
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use crate::parser::ScanInfo;
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const LUT_BITS: u8 = 8;
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#[derive(Debug)]
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pub struct HuffmanDecoder {
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bits: u64,
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num_bits: u8,
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marker: Option<Marker>,
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}
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impl HuffmanDecoder {
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pub fn new() -> HuffmanDecoder {
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HuffmanDecoder {
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bits: 0,
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num_bits: 0,
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marker: None,
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}
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}
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// Section F.2.2.3
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// Figure F.16
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pub fn decode<R: Read>(&mut self, reader: &mut R, table: &HuffmanTable) -> Result<u8> {
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if self.num_bits < 16 {
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self.read_bits(reader)?;
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}
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let (value, size) = table.lut[self.peek_bits(LUT_BITS) as usize];
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if size > 0 {
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self.consume_bits(size);
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Ok(value)
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}
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else {
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let bits = self.peek_bits(16);
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for i in LUT_BITS .. 16 {
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let code = (bits >> (15 - i)) as i32;
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if code <= table.maxcode[i as usize] {
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self.consume_bits(i + 1);
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let index = (code + table.delta[i as usize]) as usize;
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return Ok(table.values[index]);
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}
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}
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Err(Error::Format("failed to decode huffman code".to_owned()))
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}
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}
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pub fn decode_fast_ac<R: Read>(&mut self, reader: &mut R, table: &HuffmanTable) -> Result<Option<(i16, u8)>> {
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if let Some(ref ac_lut) = table.ac_lut {
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if self.num_bits < LUT_BITS {
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self.read_bits(reader)?;
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}
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let (value, run_size) = ac_lut[self.peek_bits(LUT_BITS) as usize];
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if run_size != 0 {
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let run = run_size >> 4;
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let size = run_size & 0x0f;
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self.consume_bits(size);
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return Ok(Some((value, run)));
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}
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}
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Ok(None)
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}
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#[inline]
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pub fn get_bits<R: Read>(&mut self, reader: &mut R, count: u8) -> Result<u16> {
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if self.num_bits < count {
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self.read_bits(reader)?;
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}
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let bits = self.peek_bits(count);
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self.consume_bits(count);
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Ok(bits)
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}
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#[inline]
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pub fn receive_extend<R: Read>(&mut self, reader: &mut R, count: u8) -> Result<i16> {
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let value = self.get_bits(reader, count)?;
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Ok(extend(value, count))
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}
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pub fn reset(&mut self) {
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self.bits = 0;
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self.num_bits = 0;
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}
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pub fn take_marker<R: Read>(&mut self, reader: &mut R) -> Result<Option<Marker>> {
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self.read_bits(reader).map(|_| self.marker.take())
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}
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#[inline]
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fn peek_bits(&mut self, count: u8) -> u16 {
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debug_assert!(count <= 16);
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debug_assert!(self.num_bits >= count);
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((self.bits >> (64 - count)) & ((1 << count) - 1)) as u16
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}
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#[inline]
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fn consume_bits(&mut self, count: u8) {
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debug_assert!(self.num_bits >= count);
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self.bits <<= count as usize;
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self.num_bits -= count;
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}
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fn read_bits<R: Read>(&mut self, reader: &mut R) -> Result<()> {
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while self.num_bits <= 56 {
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// Fill with zero bits if we have reached the end.
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let byte = match self.marker {
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Some(_) => 0,
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None => read_u8(reader)?,
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};
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if byte == 0xFF {
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let mut next_byte = read_u8(reader)?;
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// Check for byte stuffing.
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if next_byte != 0x00 {
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// We seem to have reached the end of entropy-coded data and encountered a
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// marker. Since we can't put data back into the reader, we have to continue
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// reading to identify the marker so we can pass it on.
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// Section B.1.1.2
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// "Any marker may optionally be preceded by any number of fill bytes, which are bytes assigned code X’FF’."
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while next_byte == 0xFF {
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next_byte = read_u8(reader)?;
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}
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match next_byte {
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0x00 => return Err(Error::Format("FF 00 found where marker was expected".to_owned())),
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_ => self.marker = Some(Marker::from_u8(next_byte).unwrap()),
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}
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continue;
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}
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}
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self.bits |= (byte as u64) << (56 - self.num_bits);
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self.num_bits += 8;
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}
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Ok(())
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}
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}
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// Section F.2.2.1
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// Figure F.12
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fn extend(value: u16, count: u8) -> i16 {
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let vt = 1 << (count as u16 - 1);
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if value < vt {
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value as i16 + (-1 << count as i16) + 1
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} else {
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value as i16
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}
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}
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#[derive(Clone, Copy, Debug, PartialEq)]
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pub enum HuffmanTableClass {
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DC,
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AC,
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}
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pub struct HuffmanTable {
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values: Vec<u8>,
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delta: [i32; 16],
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maxcode: [i32; 16],
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lut: [(u8, u8); 1 << LUT_BITS],
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ac_lut: Option<[(i16, u8); 1 << LUT_BITS]>,
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}
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impl HuffmanTable {
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pub fn new(bits: &[u8; 16], values: &[u8], class: HuffmanTableClass) -> Result<HuffmanTable> {
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let (huffcode, huffsize) = derive_huffman_codes(bits)?;
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// Section F.2.2.3
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// Figure F.15
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// delta[i] is set to VALPTR(I) - MINCODE(I)
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let mut delta = [0i32; 16];
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let mut maxcode = [-1i32; 16];
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let mut j = 0;
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for i in 0 .. 16 {
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if bits[i] != 0 {
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delta[i] = j as i32 - huffcode[j] as i32;
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j += bits[i] as usize;
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maxcode[i] = huffcode[j - 1] as i32;
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}
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}
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// Build a lookup table for faster decoding.
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let mut lut = [(0u8, 0u8); 1 << LUT_BITS];
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for (i, &size) in huffsize.iter().enumerate().filter(|&(_, &size)| size <= LUT_BITS) {
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let bits_remaining = LUT_BITS - size;
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let start = (huffcode[i] << bits_remaining) as usize;
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let val = (values[i], size);
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for b in &mut lut[start..][..1 << bits_remaining] {
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*b = val;
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}
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}
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// Build a lookup table for small AC coefficients which both decodes the value and does the
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// equivalent of receive_extend.
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let ac_lut = match class {
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HuffmanTableClass::DC => None,
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HuffmanTableClass::AC => {
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let mut table = [(0i16, 0u8); 1 << LUT_BITS];
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for (i, &(value, size)) in lut.iter().enumerate() {
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let run_length = value >> 4;
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let magnitude_category = value & 0x0f;
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if magnitude_category > 0 && size + magnitude_category <= LUT_BITS {
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let unextended_ac_value = (((i << size) & ((1 << LUT_BITS) - 1)) >> (LUT_BITS - magnitude_category)) as u16;
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let ac_value = extend(unextended_ac_value, magnitude_category);
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table[i] = (ac_value, (run_length << 4) | (size + magnitude_category));
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}
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}
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Some(table)
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},
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};
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Ok(HuffmanTable {
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values: values.to_vec(),
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delta,
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maxcode,
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lut,
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ac_lut,
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})
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}
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}
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// Section C.2
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fn derive_huffman_codes(bits: &[u8; 16]) -> Result<(Vec<u16>, Vec<u8>)> {
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// Figure C.1
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let huffsize = bits.iter()
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.enumerate()
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.fold(Vec::new(), |mut acc, (i, &value)| {
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acc.extend(iter::repeat((i + 1) as u8).take(value as usize));
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acc
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});
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// Figure C.2
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let mut huffcode = vec![0u16; huffsize.len()];
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let mut code_size = huffsize[0];
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let mut code = 0u32;
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for (i, &size) in huffsize.iter().enumerate() {
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while code_size < size {
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code <<= 1;
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code_size += 1;
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}
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if code >= (1u32 << size) {
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return Err(Error::Format("bad huffman code length".to_owned()));
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}
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huffcode[i] = code as u16;
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code += 1;
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}
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Ok((huffcode, huffsize))
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}
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// https://www.loc.gov/preservation/digital/formats/fdd/fdd000063.shtml
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// "Avery Lee, writing in the rec.video.desktop newsgroup in 2001, commented that "MJPEG, or at
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// least the MJPEG in AVIs having the MJPG fourcc, is restricted JPEG with a fixed -- and
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// *omitted* -- Huffman table. The JPEG must be YCbCr colorspace, it must be 4:2:2, and it must
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// use basic Huffman encoding, not arithmetic or progressive.... You can indeed extract the
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// MJPEG frames and decode them with a regular JPEG decoder, but you have to prepend the DHT
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// segment to them, or else the decoder won't have any idea how to decompress the data.
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// The exact table necessary is given in the OpenDML spec.""
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pub fn fill_default_mjpeg_tables(scan: &ScanInfo,
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dc_huffman_tables: &mut[Option<HuffmanTable>],
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ac_huffman_tables: &mut[Option<HuffmanTable>]) {
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// Section K.3.3
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if dc_huffman_tables[0].is_none() && scan.dc_table_indices.iter().any(|&i| i == 0) {
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// Table K.3
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dc_huffman_tables[0] = Some(HuffmanTable::new(
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&[0x00, 0x01, 0x05, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00],
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&[0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B], HuffmanTableClass::DC).unwrap());
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}
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if dc_huffman_tables[1].is_none() && scan.dc_table_indices.iter().any(|&i| i == 1) {
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// Table K.4
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dc_huffman_tables[1] = Some(HuffmanTable::new(
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&[0x00, 0x03, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00],
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&[0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B], HuffmanTableClass::DC).unwrap());
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}
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if ac_huffman_tables[0].is_none() && scan.ac_table_indices.iter().any(|&i| i == 0) {
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// Table K.5
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ac_huffman_tables[0] = Some(HuffmanTable::new(
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&[0x00, 0x02, 0x01, 0x03, 0x03, 0x02, 0x04, 0x03, 0x05, 0x05, 0x04, 0x04, 0x00, 0x00, 0x01, 0x7D],
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&[0x01, 0x02, 0x03, 0x00, 0x04, 0x11, 0x05, 0x12, 0x21, 0x31, 0x41, 0x06, 0x13, 0x51, 0x61, 0x07,
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0x22, 0x71, 0x14, 0x32, 0x81, 0x91, 0xA1, 0x08, 0x23, 0x42, 0xB1, 0xC1, 0x15, 0x52, 0xD1, 0xF0,
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0x24, 0x33, 0x62, 0x72, 0x82, 0x09, 0x0A, 0x16, 0x17, 0x18, 0x19, 0x1A, 0x25, 0x26, 0x27, 0x28,
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0x29, 0x2A, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49,
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0x4A, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5A, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69,
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0x6A, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7A, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89,
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0x8A, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9A, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7,
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0xA8, 0xA9, 0xAA, 0xB2, 0xB3, 0xB4, 0xB5, 0xB6, 0xB7, 0xB8, 0xB9, 0xBA, 0xC2, 0xC3, 0xC4, 0xC5,
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0xC6, 0xC7, 0xC8, 0xC9, 0xCA, 0xD2, 0xD3, 0xD4, 0xD5, 0xD6, 0xD7, 0xD8, 0xD9, 0xDA, 0xE1, 0xE2,
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0xE3, 0xE4, 0xE5, 0xE6, 0xE7, 0xE8, 0xE9, 0xEA, 0xF1, 0xF2, 0xF3, 0xF4, 0xF5, 0xF6, 0xF7, 0xF8,
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0xF9, 0xFA
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], HuffmanTableClass::AC).unwrap());
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}
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if ac_huffman_tables[1].is_none() && scan.ac_table_indices.iter().any(|&i| i == 1) {
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// Table K.6
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ac_huffman_tables[1] = Some(HuffmanTable::new(
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&[0x00, 0x02, 0x01, 0x02, 0x04, 0x04, 0x03, 0x04, 0x07, 0x05, 0x04, 0x04, 0x00, 0x01, 0x02, 0x77],
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&[0x00, 0x01, 0x02, 0x03, 0x11, 0x04, 0x05, 0x21, 0x31, 0x06, 0x12, 0x41, 0x51, 0x07, 0x61, 0x71,
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0x13, 0x22, 0x32, 0x81, 0x08, 0x14, 0x42, 0x91, 0xA1, 0xB1, 0xC1, 0x09, 0x23, 0x33, 0x52, 0xF0,
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0x15, 0x62, 0x72, 0xD1, 0x0A, 0x16, 0x24, 0x34, 0xE1, 0x25, 0xF1, 0x17, 0x18, 0x19, 0x1A, 0x26,
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0x27, 0x28, 0x29, 0x2A, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
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0x49, 0x4A, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5A, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68,
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0x69, 0x6A, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7A, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
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0x88, 0x89, 0x8A, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9A, 0xA2, 0xA3, 0xA4, 0xA5,
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0xA6, 0xA7, 0xA8, 0xA9, 0xAA, 0xB2, 0xB3, 0xB4, 0xB5, 0xB6, 0xB7, 0xB8, 0xB9, 0xBA, 0xC2, 0xC3,
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0xC4, 0xC5, 0xC6, 0xC7, 0xC8, 0xC9, 0xCA, 0xD2, 0xD3, 0xD4, 0xD5, 0xD6, 0xD7, 0xD8, 0xD9, 0xDA,
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0xE2, 0xE3, 0xE4, 0xE5, 0xE6, 0xE7, 0xE8, 0xE9, 0xEA, 0xF2, 0xF3, 0xF4, 0xF5, 0xF6, 0xF7, 0xF8,
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0xF9, 0xFA
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], HuffmanTableClass::AC).unwrap());
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}
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}
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