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avcodec/exrenc: move float2half code to own header

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This commit is contained in:
Paul B Mahol 2021-02-28 11:57:04 +01:00
parent cc85ca1cb3
commit cf2f8dcc6a
2 changed files with 72 additions and 47 deletions
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52
libavcodec/exrenc.c
View File

@ -34,6 +34,7 @@
#include "avcodec.h"
#include "bytestream.h"
#include "internal.h"
#include "float2half.h"
enum ExrCompr {
EXR_RAW,
@ -87,54 +88,11 @@ typedef struct EXRContext {
uint8_t shifttable[512];
} EXRContext;
static void half_tables(EXRContext *s)
{
for (int i = 0; i < 256; i++) {
int e = i - 127;
if (e < -24) { // Very small numbers map to zero
s->basetable[i|0x000] = 0x0000;
s->basetable[i|0x100] = 0x8000;
s->shifttable[i|0x000] = 24;
s->shifttable[i|0x100] = 24;
} else if (e < -14) { // Small numbers map to denorms
s->basetable[i|0x000] = (0x0400>>(-e-14));
s->basetable[i|0x100] = (0x0400>>(-e-14)) | 0x8000;
s->shifttable[i|0x000] = -e-1;
s->shifttable[i|0x100] = -e-1;
} else if (e <= 15) { // Normal numbers just lose precision
s->basetable[i|0x000] = ((e + 15) << 10);
s->basetable[i|0x100] = ((e + 15) << 10) | 0x8000;
s->shifttable[i|0x000] = 13;
s->shifttable[i|0x100] = 13;
} else if (e < 128) { // Large numbers map to Infinity
s->basetable[i|0x000] = 0x7C00;
s->basetable[i|0x100] = 0xFC00;
s->shifttable[i|0x000] = 24;
s->shifttable[i|0x100] = 24;
} else{ // Infinity and NaN's stay Infinity and NaN's
s->basetable[i|0x000] = 0x7C00;
s->basetable[i|0x100] = 0xFC00;
s->shifttable[i|0x000] = 13;
s->shifttable[i|0x100] = 13;
}
}
}
static uint16_t float2half(EXRContext *s, uint32_t f)
{
uint16_t h;
h = s->basetable[(f >> 23) & 0x1ff] + ((f & 0x007fffff) >> s->shifttable[(f >> 23) & 0x1ff]);
return h;
}
static int encode_init(AVCodecContext *avctx)
{
EXRContext *s = avctx->priv_data;
half_tables(s);
float2half_tables(s->basetable, s->shifttable);
switch (avctx->pix_fmt) {
case AV_PIX_FMT_GBRPF32:
@ -290,7 +248,7 @@ static int encode_scanline_rle(EXRContext *s, const AVFrame *frame)
uint32_t *src = (uint32_t *)(frame->data[ch] + y * frame->linesize[ch]);
for (int x = 0; x < frame->width; x++)
dst[x] = float2half(s, src[x]);
dst[x] = float2half(src[x], s->basetable, s->shifttable);
}
break;
}
@ -358,7 +316,7 @@ static int encode_scanline_zip(EXRContext *s, const AVFrame *frame)
uint32_t *src = (uint32_t *)(frame->data[ch] + (y * s->scanline_height + l) * frame->linesize[ch]);
for (int x = 0; x < frame->width; x++)
dst[x] = float2half(s, src[x]);
dst[x] = float2half(src[x], s->basetable, s->shifttable);
}
}
break;
@ -516,7 +474,7 @@ static int encode_frame(AVCodecContext *avctx, AVPacket *pkt,
uint32_t *src = (uint32_t *)(frame->data[ch] + y * frame->linesize[ch]);
for (int x = 0; x < frame->width; x++)
bytestream2_put_le16(pb, float2half(s, src[x]));
bytestream2_put_le16(pb, float2half(src[x], s->basetable, s->shifttable));
}
}
}

67
libavcodec/float2half.h Normal file
View File

@ -0,0 +1,67 @@
/*
* 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_FLOAT2HALF_H
#define AVCODEC_FLOAT2HALF_H
#include <stdint.h>
static void float2half_tables(uint16_t *basetable, uint8_t *shifttable)
{
for (int i = 0; i < 256; i++) {
int e = i - 127;
if (e < -24) { // Very small numbers map to zero
basetable[i|0x000] = 0x0000;
basetable[i|0x100] = 0x8000;
shifttable[i|0x000] = 24;
shifttable[i|0x100] = 24;
} else if (e < -14) { // Small numbers map to denorms
basetable[i|0x000] = (0x0400>>(-e-14));
basetable[i|0x100] = (0x0400>>(-e-14)) | 0x8000;
shifttable[i|0x000] = -e-1;
shifttable[i|0x100] = -e-1;
} else if (e <= 15) { // Normal numbers just lose precision
basetable[i|0x000] = ((e + 15) << 10);
basetable[i|0x100] = ((e + 15) << 10) | 0x8000;
shifttable[i|0x000] = 13;
shifttable[i|0x100] = 13;
} else if (e < 128) { // Large numbers map to Infinity
basetable[i|0x000] = 0x7C00;
basetable[i|0x100] = 0xFC00;
shifttable[i|0x000] = 24;
shifttable[i|0x100] = 24;
} else{ // Infinity and NaN's stay Infinity and NaN's
basetable[i|0x000] = 0x7C00;
basetable[i|0x100] = 0xFC00;
shifttable[i|0x000] = 13;
shifttable[i|0x100] = 13;
}
}
}
static uint16_t float2half(uint32_t f, uint16_t *basetable, uint8_t *shifttable)
{
uint16_t h;
h = basetable[(f >> 23) & 0x1ff] + ((f & 0x007fffff) >> shifttable[(f >> 23) & 0x1ff]);
return h;
}
#endif /* AVCODEC_FLOAT2HALF_H */