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Fix crash on width or height of 1
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Zero bits were incorrectly chosen to encode a dimension of 1;
enforce a minimum of 1 bit per dimension.

Dimensions smaller than 16 are only admitted for still_picture.
Add encode-decode tests for these tiny images.
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barrbrain committed Jan 20, 2021
1 parent b03c614 commit ae0cfad
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Showing 2 changed files with 10 additions and 5 deletions.
8 changes: 4 additions & 4 deletions src/header.rs
Original file line number Diff line number Diff line change
Expand Up @@ -856,8 +856,8 @@ impl<W: io::Write> UncompressedHeader for BitWriter<W, BigEndian> {
// when we add support for it.
let width = fi.width - 1;
let height = fi.height - 1;
let width_bits = 32 - (width as u32).leading_zeros();
let height_bits = 32 - (height as u32).leading_zeros();
let width_bits = log_in_base_2(fi.width as u32) as u32 + 1;
let height_bits = log_in_base_2(fi.height as u32) as u32 + 1;
assert!(width_bits <= 16);
assert!(height_bits <= 16);
self.write(4, width_bits - 1)?;
Expand All @@ -875,8 +875,8 @@ impl<W: io::Write> UncompressedHeader for BitWriter<W, BigEndian> {
if fi.frame_size_override_flag {
let width = fi.width - 1;
let height = fi.height - 1;
let width_bits = 32 - (width as u32).leading_zeros();
let height_bits = 32 - (height as u32).leading_zeros();
let width_bits = log_in_base_2(fi.width as u32) as u32 + 1;
let height_bits = log_in_base_2(fi.height as u32) as u32 + 1;
assert!(width_bits <= 16);
assert!(height_bits <= 16);
self.write(width_bits, width as u16)?;
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7 changes: 6 additions & 1 deletion src/test_encode_decode/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -286,6 +286,10 @@ mod small_dimension {

mod tiny_dimension {
test_dimensions! {
(1, 1),
(2, 2),
(4, 4),
(8, 8),
(16, 16),
(32, 32),
(64, 64),
Expand All @@ -297,6 +301,7 @@ fn dimension(w: usize, h: usize, decoder: &str) {
let quantizer = 100;
let limit = 1;
let speed = 10;
let still_picture = w < 16 || h < 16;

let mut dec = get_decoder::<u8>(decoder, w as usize, h as usize);
dec.encode_decode(
Expand All @@ -315,7 +320,7 @@ fn dimension(w: usize, h: usize, decoder: &str) {
0,
0,
0,
false,
still_picture,
);
}

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