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jxl-frame: EC upsampling check #34

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merged 2 commits into from
Jun 6, 2023
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jxl-frame: EC upsampling check #34

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76afd1f
jxl-image: ExtraChannelInfo `dim_shift` check
EugeneVert Jun 4, 2023
8a44c7b
jxl-frame: EC upsampling check
EugeneVert Jun 6, 2023
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5 changes: 5 additions & 0 deletions crates/jxl-image/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -231,7 +231,12 @@ impl<Ctx> Bundle<Ctx> for ExtraChannelInfo {

let ty_id = read_bits!(bitstream, Enum(ExtraChannelTypeRaw))?;
let bit_depth = BitDepth::parse(bitstream, ())?;

let dim_shift = read_bits!(bitstream, U32(0, 3, 4, 1 + u(3)))?;
if (1usize << dim_shift) > 8 {
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@tirr-c tirr-c Jun 6, 2023 •
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As discussed in jxl discord chat, there's something wrong in the check in libjxl; this makes decoded U32 value of 4 (10 in bitstream) instantly invalid. Instead we could defer the check to the frame header decoding.

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Agreed, it seems to be an early check for dim_shift when ec_upsampling is not yet known.

return Err(jxl_bitstream::Error::ValidationFailed("dim_shift too large"))
}

let name = Name::parse(bitstream, ())?;

let ty = match ty_id {
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