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avcodec/mpeg12dec: Don't initialize unused parts of ScanTable

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The MPEG-1/2 decoders don't need ScanTable.raster_end
(as the coefficients are unquantized as they are parsed).

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt
2025-02-24 20:43:46 +01:00
parent e6657d499a
commit 79d6657e13
1 changed files with 7 additions and 6 deletions
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13
libavcodec/mpeg12dec.c
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@ -1228,10 +1228,10 @@ static int mpeg_decode_picture_coding_extension(Mpeg1Context *s1)
s->chroma_420_type = get_bits1(&s->gb);
s->progressive_frame = get_bits1(&s->gb);
// We only initialize intra_scantable, as both scantables always coincide
// and all code therefore only uses the intra one.
ff_init_scantable(s->idsp.idct_permutation, &s->intra_scantable,
s->alternate_scan ? ff_alternate_vertical_scan : ff_zigzag_direct);
// We only initialize intra_scantable.permutated, as this is all we use.
ff_permute_scantable(s->intra_scantable.permutated,
s->alternate_scan ? ff_alternate_vertical_scan : ff_zigzag_direct,
s->idsp.idct_permutation);
/* composite display not parsed */
ff_dlog(s->avctx, "intra_dc_precision=%d\n", s->intra_dc_precision);
@ -2803,8 +2803,9 @@ static int ipu_decode_frame(AVCodecContext *avctx, AVFrame *frame,
m->intra_vlc_format = !!(s->flags & 0x20);
m->alternate_scan = !!(s->flags & 0x10);
ff_init_scantable(m->idsp.idct_permutation, &m->intra_scantable,
s->flags & 0x10 ? ff_alternate_vertical_scan : ff_zigzag_direct);
ff_permute_scantable(m->intra_scantable.permutated,
s->flags & 0x10 ? ff_alternate_vertical_scan : ff_zigzag_direct,
m->idsp.idct_permutation);
m->last_dc[0] = m->last_dc[1] = m->last_dc[2] = 1 << (7 + (s->flags & 3));
m->qscale = 1;