[Mp4-tech] Correction in function "biari_init_context" of JM encoder

[Anup Mankar]

Hi,
I came across what seemed to me as a small inconsistency as regards the
implementation of context initialization function "biari_init_context"
in version 10.2 of the JM encoder.
The line reads
pstate = ((ini[0]* max(0, img->qp)) >> 4) + ini[1];
which according to the standard should be
pstate = ((ini[0]* max(0, img->currentSlice->qp)) >> 4) + ini[1];
The standard says the following in Section 9.3.1.1:
preCtxState = Clip3( 1, 126, ( ( m ? Clip3( 0, 51, SliceQPY ) ) >> 4 ) +
n )
There might be inconsistent results (mostly leading to misinterpretation
of information being written by the encoder) since the context
initialization will not take place as suggested by the standard.
Version 10.2 was the latest I could find. In all probability this bug
may have already been fixed in the latest version of JM codec. However I
thought it was my responsibility to bring it to your notice.
Thank you and regards,
Anup Mankar
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