This commit fixes the problem described below on the integer version of the
inverse 9-7 DWT processing (FF_DWT97_INT,
https://trac.ffmpeg.org/ticket/10123), which is activated with `-flags
+bitexact`.
I went through the code path for 9-7 transform (integer) and improved precision
to match conformance codestream. As a result, the encoded codestream size is
slightly larger for a given Q value. For example, `-flags +bitexact -i lena.pnm
-q: 20 -format j2k -y tmp.j2c` gives 13K (HEAD) and 19K (with this patch)`
- Problem
- The tests for the following codestreams were failed with `-flags +bitexact`.
- p0_04.j2k, p0_05.j2k, p0_09.j2k, p1_02.j2k, p1_03.j2k, p1_06.j2k.
- ds0_ht_04_b11.j2k, ds0_ht_04_b12.j2k, ds0_ht_05_b11.j2k,
ds0_ht_05_b12.j2k, ds0_ht_09_b11.j2k, ds1_ht_02_b11.j2k, ds1_ht_02_b12.j2k,
ds1_ht_03_b11.j2k, ds1_ht_03_b12.j2k, ds1_ht_06_b11.j2k.
- These failure comes from the insufficient precision of the fixed-point
implementation of the 9-7 DWT.
Signed-off-by: Osamu Watanabe <owata...@es.takushoku-u.ac.jp>
---
libavcodec/jpeg2000.c | 6 ++----
libavcodec/jpeg2000dec.c | 2 +-
libavcodec/jpeg2000dwt.c | 43 +++++++++++++++++++++++-----------------
3 files changed, 28 insertions(+), 23 deletions(-)
diff --git a/libavcodec/jpeg2000.c b/libavcodec/jpeg2000.c
index d6ffb02319..f1a7d55ae1 100644
--- a/libavcodec/jpeg2000.c
+++ b/libavcodec/jpeg2000.c
@@ -260,9 +260,7 @@ static void init_band_stepsize(AVCodecContext *avctx,
band->f_stepsize *= F_LFTG_X * F_LFTG_X * 4;
break;
}
- if (codsty->transform == FF_DWT97) {
- band->f_stepsize *= pow(F_LFTG_K, 2*(codsty->nreslevels2decode -
reslevelno) + lband - 2);
- }
+ band->f_stepsize *= pow(F_LFTG_K, 2*(codsty->nreslevels2decode -
reslevelno) + lband - 2);
}
if (band->f_stepsize > (INT_MAX >> 15)) {
@@ -270,7 +268,7 @@ static void init_band_stepsize(AVCodecContext *avctx,
av_log(avctx, AV_LOG_ERROR, "stepsize out of range\n");
}
- band->i_stepsize = band->f_stepsize * (1 << 15);
+ band->i_stepsize = lrint(band->f_stepsize * (1 << 15) + 0.5f);
/* FIXME: In OpenJPEG code stepsize = stepsize * 0.5. Why?
* If not set output of entropic decoder is not correct. */
diff --git a/libavcodec/jpeg2000dec.c b/libavcodec/jpeg2000dec.c
index 2e09b279dc..f68e41ed6a 100644
--- a/libavcodec/jpeg2000dec.c
+++ b/libavcodec/jpeg2000dec.c
@@ -2136,7 +2136,7 @@ static void dequantization_int_97(int x, int y,
Jpeg2000Cblk *cblk,
int32_t *datap = &comp->i_data[(comp->coord[0][1] - comp->coord[0][0])
* (y + j) + x];
int *src = t1->data + j*t1->stride;
for (i = 0; i < w; ++i)
- datap[i] = (src[i] * (int64_t)band->i_stepsize + (1<<15)) >> 16;
+ datap[i] = (int32_t)(src[i] * (int64_t)band->i_stepsize + (1 <<
14)) >> 15;
}
}
diff --git a/libavcodec/jpeg2000dwt.c b/libavcodec/jpeg2000dwt.c
index 34e33553f7..d24f15d39b 100644
--- a/libavcodec/jpeg2000dwt.c
+++ b/libavcodec/jpeg2000dwt.c
@@ -39,12 +39,12 @@
/* Lifting parameters in integer format.
* Computed as param = (float param) * (1 << 16) */
-#define I_LFTG_ALPHA 103949ll
-#define I_LFTG_BETA 3472ll
-#define I_LFTG_GAMMA 57862ll
-#define I_LFTG_DELTA 29066ll
-#define I_LFTG_K 80621ll
-#define I_LFTG_X 53274ll
+#define I_LFTG_ALPHA_PRIME 38413ll // = 103949 - 65536, (= alpha - 1.0)
+#define I_LFTG_BETA 3472ll
+#define I_LFTG_GAMMA 57862ll
+#define I_LFTG_DELTA 29066ll
+#define I_LFTG_K 80621ll
+#define I_LFTG_X 53274ll
#define I_PRESHIFT 8
static inline void extend53(int *p, int i0, int i1)
@@ -234,8 +234,11 @@ static void sd_1d97_int(int *p, int i0, int i1)
extend97_int(p, i0, i1);
i0++; i1++;
- for (i = (i0>>1) - 2; i < (i1>>1) + 1; i++)
- p[2 * i + 1] -= (I_LFTG_ALPHA * (p[2 * i] + p[2 * i + 2]) + (1 <<
15)) >> 16;
+ for (i = (i0>>1) - 2; i < (i1>>1) + 1; i++) {
+ const int64_t sum = p[2 * i] + p[2 * i + 2];
+ p[2 * i + 1] -= sum;
+ p[2 * i + 1] -= (I_LFTG_ALPHA_PRIME * sum + (1 << 15)) >> 16;
+ }
for (i = (i0>>1) - 1; i < (i1>>1) + 1; i++)
p[2 * i] -= (I_LFTG_BETA * (p[2 * i - 1] + p[2 * i + 1]) + (1 <<
15)) >> 16;
for (i = (i0>>1) - 1; i < (i1>>1); i++)
@@ -276,7 +279,7 @@ static void dwt_encode97_int(DWTContext *s, int *t)
// copy back and deinterleave
for (i = mv; i < lv; i+=2, j++)
- t[w*j + lp] = ((l[i] * I_LFTG_X) + (1 << 15)) >> 16;
+ t[w*j + lp] = l[i];
for (i = 1-mv; i < lv; i+=2, j++)
t[w*j + lp] = l[i];
}
@@ -293,7 +296,7 @@ static void dwt_encode97_int(DWTContext *s, int *t)
// copy back and deinterleave
for (i = mh; i < lh; i+=2, j++)
- t[w*lp + j] = ((l[i] * I_LFTG_X) + (1 << 15)) >> 16;
+ t[w*lp + j] = l[i];
for (i = 1-mh; i < lh; i+=2, j++)
t[w*lp + j] = l[i];
}
@@ -301,7 +304,7 @@ static void dwt_encode97_int(DWTContext *s, int *t)
}
for (i = 0; i < w * h; i++)
- t[i] = (t[i] + ((1<<I_PRESHIFT)>>1)) >> I_PRESHIFT;
+ t[i] = (t[i] + ((1<<(I_PRESHIFT))>>1)) >> (I_PRESHIFT);
}
static void sr_1d53(unsigned *p, int i0, int i1)
@@ -471,8 +474,11 @@ static void sr_1d97_int(int32_t *p, int i0, int i1)
for (i = (i0 >> 1); i < (i1 >> 1) + 1; i++)
p[2 * i] += (I_LFTG_BETA * (p[2 * i - 1] + (int64_t)p[2 * i + 1])
+ (1 << 15)) >> 16;
/* step 6 */
- for (i = (i0 >> 1); i < (i1 >> 1); i++)
- p[2 * i + 1] += (I_LFTG_ALPHA * (p[2 * i] + (int64_t)p[2 * i + 2])
+ (1 << 15)) >> 16;
+ for (i = (i0 >> 1); i < (i1 >> 1); i++) {
+ const int64_t sum = p[2 * i] + (int64_t) p[2 * i + 2];
+ p[2 * i + 1] += sum;
+ p[2 * i + 1] += (I_LFTG_ALPHA_PRIME * sum + (1 << 15)) >> 16;
+ }
}
static void dwt_decode97_int(DWTContext *s, int32_t *t)
@@ -500,9 +506,9 @@ static void dwt_decode97_int(DWTContext *s, int32_t *t)
l = line + mh;
for (lp = 0; lp < lv; lp++) {
int i, j = 0;
- // rescale with interleaving
+ // interleaving
for (i = mh; i < lh; i += 2, j++)
- l[i] = ((data[w * lp + j] * I_LFTG_K) + (1 << 15)) >> 16;
+ l[i] = data[w * lp + j];
for (i = 1 - mh; i < lh; i += 2, j++)
l[i] = data[w * lp + j];
@@ -516,9 +522,9 @@ static void dwt_decode97_int(DWTContext *s, int32_t *t)
l = line + mv;
for (lp = 0; lp < lh; lp++) {
int i, j = 0;
- // rescale with interleaving
+ // interleaving
for (i = mv; i < lv; i += 2, j++)
- l[i] = ((data[w * j + lp] * I_LFTG_K) + (1 << 15)) >> 16;
+ l[i] = data[w * j + lp];
for (i = 1 - mv; i < lv; i += 2, j++)
l[i] = data[w * j + lp];
@@ -530,7 +536,8 @@ static void dwt_decode97_int(DWTContext *s, int32_t *t)
}
for (i = 0; i < w * h; i++)
- data[i] = (data[i] + ((1LL<<I_PRESHIFT)>>1)) >> I_PRESHIFT;
+ // We shift down by `I_PRESHIFT + 1` because the input coefficients
`datap[]` were shifted down to 1 bit above from the binary point.
+ data[i] = (int32_t)(data[i] + ((1LL<<(I_PRESHIFT + 1))>>1)) >>
(I_PRESHIFT + 1);
}
int ff_jpeg2000_dwt_init(DWTContext *s, int border[2][2],
--
2.43.0
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