Hi!
Attached patch makes the output of the reference sample p0_03.j2k
bit-exact with opj_decompress and kdu_render and more similar to
jasper's output.
Please comment, Carl Eugen
From de80453a8decd95b4a71cea71b20ba0bd74485cb Mon Sep 17 00:00:00 2001
From: Carl Eugen Hoyos <ceffm...@gmail.com>
Date: Sat, 25 Apr 2020 18:31:22 +0200
Subject: [PATCH] lavc/jpeg2000dec: Scale 4-7 bit output to 8 bits.
Makes p0_03.j2k output bitexact with opj_decompress and kdu_render
and more similar with the output of jasper.
---
libavcodec/jpeg2000dec.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/libavcodec/jpeg2000dec.c b/libavcodec/jpeg2000dec.c
index 460a4ad95c..8d7c729530 100644
--- a/libavcodec/jpeg2000dec.c
+++ b/libavcodec/jpeg2000dec.c
@@ -1938,7 +1938,9 @@ static inline void tile_codeblocks(Jpeg2000DecoderContext *s, Jpeg2000Tile *tile
int val = lrintf(*datap) + (1 << (cbps - 1)); \
/* DC level shift and clip see ISO 15444-1:2002 G.1.2 */ \
val = av_clip(val, 0, (1 << cbps) - 1); \
- *dst = val << (precision - cbps); \
+ *dst = val << ((precision < 8 ? 8 : precision) - cbps); \
+ if (precision < 8) \
+ *dst |= *dst >> (8 - precision); \
datap++; \
dst += pixelsize; \
} \
@@ -1947,7 +1949,9 @@ static inline void tile_codeblocks(Jpeg2000DecoderContext *s, Jpeg2000Tile *tile
int val = *i_datap + (1 << (cbps - 1)); \
/* DC level shift and clip see ISO 15444-1:2002 G.1.2 */ \
val = av_clip(val, 0, (1 << cbps) - 1); \
- *dst = val << (precision - cbps); \
+ *dst = val << ((precision < 8 ? 8 : precision) - cbps); \
+ if (precision < 8) \
+ *dst |= *dst >> (8 - precision); \
i_datap++; \
dst += pixelsize; \
} \
@@ -1989,7 +1993,7 @@ static int jpeg2000_decode_tile(AVCodecContext *avctx, void *td,
}
if (s->precision <= 8) {
- write_frame_8(s, tile, picture, 8);
+ write_frame_8(s, tile, picture, s->precision);
} else {
int precision = picture->format == AV_PIX_FMT_XYZ12 ||
picture->format == AV_PIX_FMT_RGB48 ||
--
2.24.1
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