Ensuring the mvdLX is compliant - #939
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The value of the mvdLX should be in the range of [-2^15, 2^15-1], as specified in H.265 7.4.9.9 Motion vector difference semantics. However there was no safety check in this area, the mvdLX have been observed to exceed the range, under some rare circumstances. This casting will cause overflow and underflow, should the mvd exceeds the int16_t range. But because of the decoding process Equation 8-94 to 8-97, and the MV itself having the range of [-2^15, 2^15-1], the decoded MV will still be correct, and mvdLX will be in the legal range.
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The value of the mvdLX should be in the range of [-2^15, 2^15-1], as specified in H.265 7.4.9.9 Motion vector difference semantics. However there was no safety check in this area, the mvdLX have been observed to exceed the range, under some rare circumstances.
This casting will cause overflow and underflow, should the mvd exceeds the int16_t range. But because of the decoding process Equation 8-94 to 8-97, and the MV itself having the range of [-2^15, 2^15-1], the decoded MV will still be correct, and mvdLX will be in the legal range.