@@ -29,8 +29,6 @@
*
* For more information on the OpenEXR format, visit:
* http://openexr.com/
- *
- * exr_half2float() is credited to Aaftab Munshi, Dan Ginsburg, Dave Shreiner.
*/
#include <float.h>
@@ -54,6 +52,7 @@
#include "exrdsp.h"
#include "get_bits.h"
#include "internal.h"
+#include "half2float.h"
#include "mathops.h"
#include "thread.h"
@@ -190,6 +189,10 @@ typedef struct EXRContext {
enum AVColorTransferCharacteristic apply_trc_type;
float gamma;
union av_intfloat32 gamma_table[65536];
+
+ uint32_t mantissatable[2048];
+ uint32_t exponenttable[64];
+ uint16_t offsettable[64];
} EXRContext;
/* -15 stored using a single precision bias of 127 */
@@ -204,55 +207,6 @@ typedef struct EXRContext {
#define HALF_FLOAT_MAX_BIASED_EXP (0x1F << 10)
-/**
- * Convert a half float as a uint16_t into a full float.
- *
- * @param hf half float as uint16_t
- *
- * @return float value
- */
-static union av_intfloat32 exr_half2float(uint16_t hf)
-{
- unsigned int sign = (unsigned int) (hf >> 15);
- unsigned int mantissa = (unsigned int) (hf & ((1 << 10) - 1));
- unsigned int exp = (unsigned int) (hf & HALF_FLOAT_MAX_BIASED_EXP);
- union av_intfloat32 f;
-
- if (exp == HALF_FLOAT_MAX_BIASED_EXP) {
- // we have a half-float NaN or Inf
- // half-float NaNs will be converted to a single precision NaN
- // half-float Infs will be converted to a single precision Inf
- exp = FLOAT_MAX_BIASED_EXP;
- mantissa <<= 13; // preserve half-float NaN bits if set
- } else if (exp == 0x0) {
- // convert half-float zero/denorm to single precision value
- if (mantissa) {
- mantissa <<= 1;
- exp = HALF_FLOAT_MIN_BIASED_EXP_AS_SINGLE_FP_EXP;
- // check for leading 1 in denorm mantissa
- while (!(mantissa & (1 << 10))) {
- // for every leading 0, decrement single precision exponent by 1
- // and shift half-float mantissa value to the left
- mantissa <<= 1;
- exp -= (1 << 23);
- }
- // clamp the mantissa to 10 bits
- mantissa &= ((1 << 10) - 1);
- // shift left to generate single-precision mantissa of 23 bits
- mantissa <<= 13;
- }
- } else {
- // shift left to generate single-precision mantissa of 23 bits
- mantissa <<= 13;
- // generate single precision biased exponent value
- exp = (exp << 13) + HALF_FLOAT_MIN_BIASED_EXP_AS_SINGLE_FP_EXP;
- }
-
- f.i = (sign << 31) | exp | mantissa;
-
- return f;
-}
-
static int zip_uncompress(EXRContext *s, const uint8_t *src, int compressed_size,
int uncompressed_size, EXRThreadData *td)
{
@@ -951,7 +905,10 @@ static int ac_uncompress(EXRContext *s, GetByteContext *gb, float *block)
n += val & 0xff;
} else {
ret = n;
- block[ff_zigzag_direct[n]] = exr_half2float(val).f;
+ block[ff_zigzag_direct[n]] = av_int2float(half2float(val,
+ s->mantissatable,
+ s->exponenttable,
+ s->offsettable));
n++;
}
}
@@ -1161,10 +1118,12 @@ static int dwa_uncompress(EXRContext *s, const uint8_t *src, int compressed_size
float *block = td->block[j];
const int idx = (x >> 3) + (y >> 3) * dc_w + dc_w * dc_h * j;
uint16_t *dc = (uint16_t *)td->dc_data;
- float dc_val = dc[idx];
+ union av_intfloat32 dc_val;
- dc_val = exr_half2float(dc_val).f;
- block[0] = dc_val;
+ dc_val.i = half2float(dc[idx], s->mantissatable,
+ s->exponenttable, s->offsettable);
+
+ block[0] = dc_val.f;
ac_uncompress(s, &agb, block);
dct_inverse(block);
}
@@ -1209,8 +1168,11 @@ static int dwa_uncompress(EXRContext *s, const uint8_t *src, int compressed_size
uint8_t *ai0 = td->rle_raw_data + y * td->xsize;
uint8_t *ai1 = td->rle_raw_data + y * td->xsize + rle_raw_size / 2;
- for (int x = 0; x < td->xsize; x++)
- ao[x] = exr_half2float(ai0[x] | (ai1[x] << 8)).i;
+ for (int x = 0; x < td->xsize; x++) {
+ uint16_t ha = ai0[x] | (ai1[x] << 8);
+
+ ao[x] = half2float(ha, s->mantissatable, s->exponenttable, s->offsettable);
+ }
}
return 0;
@@ -1450,7 +1412,11 @@ static int decode_block(AVCodecContext *avctx, void *tdata,
}
} else {
for (x = 0; x < xsize; x++) {
- *ptr_x++ = exr_half2float(bytestream_get_le16(&src));
+ ptr_x[0].i = half2float(bytestream_get_le16(&src),
+ s->mantissatable,
+ s->exponenttable,
+ s->offsettable);
+ ptr_x++;
}
}
}
@@ -2237,6 +2203,8 @@ static av_cold int decode_init(AVCodecContext *avctx)
float one_gamma = 1.0f / s->gamma;
avpriv_trc_function trc_func = NULL;
+ half2float_table(s->mantissatable, s->exponenttable, s->offsettable);
+
s->avctx = avctx;
ff_exrdsp_init(&s->dsp);
@@ -2248,18 +2216,18 @@ static av_cold int decode_init(AVCodecContext *avctx)
trc_func = avpriv_get_trc_function_from_trc(s->apply_trc_type);
if (trc_func) {
for (i = 0; i < 65536; ++i) {
- t = exr_half2float(i);
+ t.i = half2float(i, s->mantissatable, s->exponenttable, s->offsettable);
t.f = trc_func(t.f);
s->gamma_table[i] = t;
}
} else {
if (one_gamma > 0.9999f && one_gamma < 1.0001f) {
for (i = 0; i < 65536; ++i) {
- s->gamma_table[i] = exr_half2float(i);
+ s->gamma_table[i].i = half2float(i, s->mantissatable, s->exponenttable, s->offsettable);
}
} else {
for (i = 0; i < 65536; ++i) {
- t = exr_half2float(i);
+ t.i = half2float(i, s->mantissatable, s->exponenttable, s->offsettable);
/* If negative value we reuse half value */
if (t.f <= 0.0f) {
s->gamma_table[i] = t;
new file mode 100644
@@ -0,0 +1,74 @@
+/*
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef AVCODEC_HALF2FLOAT_H
+#define AVCODEC_HALF2FLOAT_H
+
+#include <stdint.h>
+
+static uint32_t convertmantissa(uint32_t i)
+{
+ uint32_t m = i << 13; // Zero pad mantissa bits
+ uint32_t e = 0; // Zero exponent
+
+ while (!(m & 0x00800000UL)){ // While not normalized
+ e -= 0x00800000UL; // Decrement exponent (1<<23)
+ m <<= 1; // Shift mantissa
+ }
+
+ m &= ~0x00800000UL; // Clear leading 1 bit
+ e += 0x38800000UL; // Adjust bias ((127-14)<<23)
+
+ return m | e; // Return combined number
+}
+
+static void half2float_table(uint32_t *mantissatable, uint32_t *exponenttable,
+ uint16_t *offsettable)
+{
+ mantissatable[0] = 0;
+ for (int i = 1; i < 1024; i++)
+ mantissatable[i] = convertmantissa(i);
+ for (int i = 1024; i < 2048; i++)
+ mantissatable[i] = 0x38000000UL + ((i - 1024) << 13UL);
+
+ exponenttable[0] = 0;
+ for (int i = 1; i < 31; i++)
+ exponenttable[i] = i << 23;
+ for (int i = 33; i < 63; i++)
+ exponenttable[i] = 0x80000000UL + ((i - 32) << 23UL);
+ exponenttable[31]= 0x47800000UL;
+ exponenttable[32]= 0x80000000UL;
+ exponenttable[63]= 0xC7800000UL;
+
+ offsettable[0] = 0;
+ for (int i = 1; i < 64; i++)
+ offsettable[i] = 1024;
+ offsettable[32] = 0;
+}
+
+static uint32_t half2float(uint16_t h, uint32_t *mantissatable, uint32_t *exponenttable,
+ uint16_t *offsettable)
+{
+ uint32_t f;
+
+ f = mantissatable[offsettable[h >> 10] + (h & 0x3ff)] + exponenttable[h >> 10];
+
+ return f;
+}
+
+#endif /* AVCODEC_HALF2FLOAT_H */
Signed-off-by: Paul B Mahol <onemda@gmail.com> --- libavcodec/exr.c | 90 +++++++++++++---------------------------- libavcodec/half2float.h | 74 +++++++++++++++++++++++++++++++++ 2 files changed, 103 insertions(+), 61 deletions(-) create mode 100644 libavcodec/half2float.h