[FFmpeg-devel] [PATCH] avcodec/exrdec: restore applying color transfer characteristics for float16 samples
James Almer
jamrial at gmail.com
Fri Mar 14 04:08:09 EET 2025
Regression since 0e917389fe73c932049635d947bba076f1709589.
This change also reverts commit 431805c096738da7661a0baee2b12fe9724dcc95.
Signed-off-by: James Almer <jamrial at gmail.com>
---
libavcodec/exr.c | 38 ++++++++++++++++++++++++++++++++++++--
1 file changed, 36 insertions(+), 2 deletions(-)
diff --git a/libavcodec/exr.c b/libavcodec/exr.c
index 4482f104d0..107281e115 100644
--- a/libavcodec/exr.c
+++ b/libavcodec/exr.c
@@ -42,6 +42,7 @@
#include "libavutil/avstring.h"
#include "libavutil/mem.h"
#include "libavutil/opt.h"
+#include "libavutil/float2half.h"
#include "libavutil/half2float.h"
#include "avcodec.h"
@@ -193,7 +194,10 @@ typedef struct EXRContext {
uint8_t *offset_table;
+ uint16_t gamma_table[65536];
+
Half2FloatTables h2f_tables;
+ Float2HalfTables f2h_tables;
} EXRContext;
static int zip_uncompress(const EXRContext *s, const uint8_t *src, int compressed_size,
@@ -1401,8 +1405,13 @@ static int decode_block(AVCodecContext *avctx, void *tdata,
}
} else if (s->pixel_type == EXR_HALF) {
// 16-bit
- for (int x = 0; x < xsize; x++, ptr_x += step)
- AV_WN16A(ptr_x, bytestream_get_le16(&src));
+ if (trc_func && (!c || (c < 3 && s->desc->flags & AV_PIX_FMT_FLAG_PLANAR))) {
+ for (int x = 0; x < xsize; x++, ptr_x += step)
+ AV_WN16A(ptr_x, s->gamma_table[bytestream_get_le16(&src)]);
+ } else {
+ for (int x = 0; x < xsize; x++, ptr_x += step)
+ AV_WN16A(ptr_x, bytestream_get_le16(&src));
+ }
}
// Zero out the end if xmax+1 is not w
@@ -2212,8 +2221,13 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *picture,
static av_cold int decode_init(AVCodecContext *avctx)
{
EXRContext *s = avctx->priv_data;
+ uint32_t i;
+ union av_intfloat32 t;
+ float one_gamma = 1.0f / s->gamma;
+ av_csp_trc_function trc_func = NULL;
ff_init_half2float_tables(&s->h2f_tables);
+ ff_init_float2half_tables(&s->f2h_tables);
s->avctx = avctx;
@@ -2223,6 +2237,26 @@ static av_cold int decode_init(AVCodecContext *avctx)
ff_bswapdsp_init(&s->bbdsp);
#endif
+ trc_func = av_csp_trc_func_from_id(s->apply_trc_type);
+ if (trc_func) {
+ for (i = 0; i < 65536; ++i) {
+ t.i = half2float(i, &s->h2f_tables);
+ t.f = trc_func(t.f);
+ s->gamma_table[i] = float2half(av_float2int(t.f), &s->f2h_tables);
+ }
+ } else if (one_gamma != 1.0f) {
+ for (i = 0; i < 65536; ++i) {
+ t.i = half2float(i, &s->h2f_tables);
+ /* If negative value we reuse half value */
+ if (t.f <= 0.0f) {
+ s->gamma_table[i] = i;
+ } else {
+ t.f = powf(t.f, one_gamma);
+ s->gamma_table[i] = float2half(t.i, &s->f2h_tables);
+ }
+ }
+ }
+
// allocate thread data, used for non EXR_RAW compression types
s->thread_data = av_calloc(avctx->thread_count, sizeof(*s->thread_data));
if (!s->thread_data)
--
2.48.1
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