FFmpeg
gamma.c
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1 /*
2  * Copyright (C) 2015 Pedro Arthur <bygrandao@gmail.com>
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #include "swscale_internal.h"
22 
23 typedef struct GammaContext
24 {
25  uint16_t *table;
26 } GammaContext;
27 
28 // gamma_convert expects 16 bit rgb format
29 // it writes directly in src slice thus it must be modifiable (done through cascade context)
30 static int gamma_convert(SwsContext *c, SwsFilterDescriptor *desc, int sliceY, int sliceH)
31 {
32  GammaContext *instance = desc->instance;
33  uint16_t *table = instance->table;
34  int srcW = desc->src->width;
35 
36  int i;
37  for (i = 0; i < sliceH; ++i) {
38  uint8_t ** src = desc->src->plane[0].line;
39  int src_pos = sliceY+i - desc->src->plane[0].sliceY;
40 
41  uint16_t *src1 = (uint16_t*)*(src+src_pos);
42  int j;
43  for (j = 0; j < srcW; ++j) {
44  uint16_t r = AV_RL16(src1 + j*4 + 0);
45  uint16_t g = AV_RL16(src1 + j*4 + 1);
46  uint16_t b = AV_RL16(src1 + j*4 + 2);
47 
48  AV_WL16(src1 + j*4 + 0, table[r]);
49  AV_WL16(src1 + j*4 + 1, table[g]);
50  AV_WL16(src1 + j*4 + 2, table[b]);
51  }
52 
53  }
54  return sliceH;
55 }
56 
57 
59 {
60  GammaContext *li = av_malloc(sizeof(GammaContext));
61  if (!li)
62  return AVERROR(ENOMEM);
63  li->table = table;
64 
65  desc->instance = li;
66  desc->src = src;
67  desc->dst = NULL;
68  desc->process = &gamma_convert;
69 
70  return 0;
71 }
72 
gamma_convert
static int gamma_convert(SwsContext *c, SwsFilterDescriptor *desc, int sliceY, int sliceH)
Definition: gamma.c:30
r
const char * r
Definition: vf_curves.c:116
AVERROR
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions
b
#define b
Definition: input.c:41
SwsFilterDescriptor
Struct which holds all necessary data for processing a slice.
Definition: swscale_internal.h:1001
table
static const uint16_t table[]
Definition: prosumer.c:206
av_malloc
#define av_malloc(s)
Definition: tableprint_vlc.h:31
g
const char * g
Definition: vf_curves.c:117
AV_RL16
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_RL16
Definition: bytestream.h:94
NULL
#define NULL
Definition: coverity.c:32
src
#define src
Definition: vp8dsp.c:255
c
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
Definition: undefined.txt:32
GammaContext::table
uint16_t * table
Definition: gamma.c:25
AV_WL16
#define AV_WL16(p, v)
Definition: intreadwrite.h:412
src1
#define src1
Definition: h264pred.c:140
i
int i
Definition: input.c:407
ff_init_gamma_convert
int ff_init_gamma_convert(SwsFilterDescriptor *desc, SwsSlice *src, uint16_t *table)
initializes gamma conversion descriptor
Definition: gamma.c:58
swscale_internal.h
SwsSlice
Struct which defines a slice of an image to be scaled or an output for a scaled slice.
Definition: swscale_internal.h:986
desc
const char * desc
Definition: libsvtav1.c:79
GammaContext
Definition: gamma.c:23
SwsContext
Definition: swscale_internal.h:283