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'Dangling' values in VC-2 bounded blocks incorrectly decoded #21

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mossblaser opened this issue Mar 3, 2021 · 0 comments
Open

'Dangling' values in VC-2 bounded blocks incorrectly decoded #21

mossblaser opened this issue Mar 3, 2021 · 0 comments

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@mossblaser
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mossblaser commented Mar 3, 2021

vc2hqdecode appears to incorrectly read values within a bounded block whose last bit(s) 'dangle' off the end of the bounded block.

The following zip file contains a series of *.vc2 files containing bitstreams in which some bits within a value dangle off the end of a bounded block. Corresponding .expected files give the expected decoder output and .actual files give the actual (incorrect) output produced by vc2hqdecode:

dangling_bounded_block_tests.zip

Each test file contains test cases for values in either the Y, C1 or C2 components and tests one of the following cases of 'dangling' bits:
dangle_types

This bug is likely to result in picture corruptions in the event that a stream using dangling values is decoded. The corruptions are likely to be mild because they will typically impact a single HF component.

Ideally, special case handling of dangling values ought to be added to fix this bug to make this decoder compatible with encoders other than vc2hqencode.

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