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avcodec/mpeg4videodec: Don't initialize unused inter_scantable

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inter_scantable is only used by the dct_unquantize_h263_inter
functions, yet this is not used by the MPEG-4 decoder at all
(in case H.263 quantization is used, the unquantization already
happens in mpeg4_decode_block()).

Also move the common initialization of ff_permute_scantable()
out of the if.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt 2024-06-11 22:45:40 +02:00
parent 0f92fecebb
commit c41818dc5d
1 changed files with 2 additions and 7 deletions
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9
libavcodec/mpeg4videodec.c
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@ -3251,22 +3251,17 @@ static int decode_vop_header(Mpeg4DecContext *ctx, GetBitContext *gb,
} else
s->alternate_scan = 0;
}
if (s->alternate_scan) {
ff_init_scantable(s->idsp.idct_permutation, &s->inter_scantable, ff_alternate_vertical_scan);
ff_init_scantable(s->idsp.idct_permutation, &s->intra_scantable, ff_alternate_vertical_scan);
ff_permute_scantable(s->permutated_intra_h_scantable, ff_alternate_vertical_scan,
s->idsp.idct_permutation);
ff_permute_scantable(s->permutated_intra_v_scantable, ff_alternate_vertical_scan,
s->idsp.idct_permutation);
} else {
ff_init_scantable(s->idsp.idct_permutation, &s->inter_scantable, ff_zigzag_direct);
ff_init_scantable(s->idsp.idct_permutation, &s->intra_scantable, ff_zigzag_direct);
ff_permute_scantable(s->permutated_intra_h_scantable, ff_alternate_horizontal_scan,
s->idsp.idct_permutation);
ff_permute_scantable(s->permutated_intra_v_scantable, ff_alternate_vertical_scan,
s->idsp.idct_permutation);
}
ff_permute_scantable(s->permutated_intra_v_scantable, ff_alternate_vertical_scan,
s->idsp.idct_permutation);
/* Skip at this point when only parsing since the remaining
* data is not useful for a parser and requires the