[FFmpeg-devel] [PATCH] libavcodec/jpeg2000dec: Fix RPCL progression order

[gautamramk at gmail.com]

From: Gautam Ramakrishnan <gautamramk at gmail.com>

This patch fixes a check in the RPCL progression order,
making it similar to the openjpeg implementation.
---
 libavcodec/jpeg2000dec.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/libavcodec/jpeg2000dec.c b/libavcodec/jpeg2000dec.c
index 18a933077e..3ea939f7d9 100644
--- a/libavcodec/jpeg2000dec.c
+++ b/libavcodec/jpeg2000dec.c
@@ -1393,22 +1393,28 @@ static int jpeg2000_decode_packets_po_iteration(Jpeg2000DecoderContext *s, Jpeg2
                         uint8_t reducedresno = codsty->nreslevels - 1 -reslevelno; //  ==> N_L - r
                         Jpeg2000ResLevel *rlevel = comp->reslevel + reslevelno;
                         unsigned prcx, prcy;
+                        int trx0, try0;
 
-                        int xc = x / s->cdx[compno];
-                        int yc = y / s->cdy[compno];
+                        if (!s->cdx[compno] || !s->cdy[compno])
+                            return AVERROR_INVALIDDATA;
+
+                        trx0 = ff_jpeg2000_ceildiv(tile->coord[0][0], s->cdx[compno] << reslevelno);
+                        try0 = ff_jpeg2000_ceildiv(tile->coord[1][0], s->cdy[compno] << reslevelno);
 
                         if (reslevelno >= codsty->nreslevels)
                             continue;
 
-                        if (yc % (1LL << (rlevel->log2_prec_height + reducedresno)) && y != tile->coord[1][0]) //FIXME this is a subset of the check
+                        if (!(y % ((uint64_t)s->cdy[compno] << (rlevel->log2_prec_height + reducedresno)) == 0 ||
+                             (y == tile->coord[1][0] && (try0 << reducedresno) % (1U << (reducedresno + rlevel->log2_prec_height)))))
                             continue;
 
-                        if (xc % (1LL << (rlevel->log2_prec_width + reducedresno)) && x != tile->coord[0][0]) //FIXME this is a subset of the check
+                        if (!(x % ((uint64_t)s->cdx[compno] << (rlevel->log2_prec_width + reducedresno)) == 0 ||
+                             (x == tile->coord[0][0] && (trx0 << reducedresno) % (1U << (reducedresno + rlevel->log2_prec_width)))))
                             continue;
 
                         // check if a precinct exists
-                        prcx   = ff_jpeg2000_ceildivpow2(xc, reducedresno) >> rlevel->log2_prec_width;
-                        prcy   = ff_jpeg2000_ceildivpow2(yc, reducedresno) >> rlevel->log2_prec_height;
+                        prcx   = ff_jpeg2000_ceildiv(x, s->cdx[compno] << reducedresno) >> rlevel->log2_prec_width;
+                        prcy   = ff_jpeg2000_ceildiv(y, s->cdy[compno] << reducedresno) >> rlevel->log2_prec_height;
                         prcx  -= ff_jpeg2000_ceildivpow2(comp->coord_o[0][0], reducedresno) >> rlevel->log2_prec_width;
                         prcy  -= ff_jpeg2000_ceildivpow2(comp->coord_o[1][0], reducedresno) >> rlevel->log2_prec_height;
 
@@ -1906,7 +1912,6 @@ static inline void tile_codeblocks(Jpeg2000DecoderContext *s, Jpeg2000Tile *tile
                             continue;
                         x = cblk->coord[0][0] - band->coord[0][0];
                         y = cblk->coord[1][0] - band->coord[1][0];
-
                         if (comp->roi_shift)
                             roi_scale_cblk(cblk, comp, &t1);
                         if (codsty->transform == FF_DWT97)
-- 
2.17.1