[M4IF Technotes] MVD=16 in MPEG4

[Luca Piccarreta]

I just gave a look at the standard and discovered that MVD=16 exists,
but must not be used when vop_fcode=1.
MVD=16 is needed when vop_fcode>1
Luca.
----- Original Message -----
From: "Chen, Kenny" <kenny.chen   intel.com>
To: <technotes   lists.m4if.org>
Sent: Friday, July 26, 2023 2:45 AM
Subject: [M4IF Technotes] MVD=16 in MPEG4
> Hi,
>
> In H.263, the table for MV difference ranges from -16 to 15.5, in MPEG4
> MVD=16 is added.
> But in VM18 there is :
> if (diff_vector < -range)
> diff_vector = diff_vector + 2*range;
> else if (diff_vector > range-1)
> diff_vector = diff_vector - 2*range;
>
> range = 32;
>
> from this equation, it seems we can not get MVD=16 from it, so why do
MPEG4
> add MVD=16 in the vlc table? Is it useless?
>
> thanks
> Ken
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