FFmpeg
Main Page
Related Pages
Modules
Data Structures
Files
Examples
File List
Globals
All
Data Structures
Files
Functions
Variables
Typedefs
Enumerations
Enumerator
Macros
Groups
Pages
libswresample
dither.c
Go to the documentation of this file.
1
/*
2
* Copyright (C) 2012 Michael Niedermayer (michaelni@gmx.at)
3
*
4
* This file is part of libswresample
5
*
6
* libswresample 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
* libswresample 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 libswresample; if not, write to the Free Software
18
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19
*/
20
21
#include "
libavutil/avassert.h
"
22
#include "
swresample_internal.h
"
23
24
void
swri_get_dither
(
SwrContext
*s,
void
*
dst
,
int
len
,
unsigned
seed
,
enum
AVSampleFormat
out_fmt,
enum
AVSampleFormat
in_fmt) {
25
double
scale
= 0;
26
#define TMP_EXTRA 2
27
double
*tmp =
av_malloc
((len +
TMP_EXTRA
) *
sizeof
(
double
));
28
int
i;
29
30
out_fmt =
av_get_packed_sample_fmt
(out_fmt);
31
in_fmt =
av_get_packed_sample_fmt
( in_fmt);
32
33
if
(in_fmt ==
AV_SAMPLE_FMT_FLT
|| in_fmt ==
AV_SAMPLE_FMT_DBL
){
34
if
(out_fmt ==
AV_SAMPLE_FMT_S32
) scale = 1.0/(1
L
<<31);
35
if
(out_fmt ==
AV_SAMPLE_FMT_S16
) scale = 1.0/(1
L
<<15);
36
if
(out_fmt ==
AV_SAMPLE_FMT_U8
) scale = 1.0/(1
L
<< 7);
37
}
38
if
(in_fmt ==
AV_SAMPLE_FMT_S32
&& out_fmt ==
AV_SAMPLE_FMT_S16
) scale = 1
L
<<16;
39
if
(in_fmt ==
AV_SAMPLE_FMT_S32
&& out_fmt ==
AV_SAMPLE_FMT_U8
) scale = 1
L
<<24;
40
if
(in_fmt ==
AV_SAMPLE_FMT_S16
&& out_fmt ==
AV_SAMPLE_FMT_U8
) scale = 1
L
<<8;
41
42
scale *= s->
dither_scale
;
43
44
for
(i=0; i<len +
TMP_EXTRA
; i++){
45
double
v;
46
seed = seed* 1664525 + 1013904223;
47
48
switch
(s->
dither_method
){
49
case
SWR_DITHER_RECTANGULAR
: v= ((double)seed) / UINT_MAX - 0.5;
break
;
50
case
SWR_DITHER_TRIANGULAR
:
51
case
SWR_DITHER_TRIANGULAR_HIGHPASS
:
52
v = ((double)seed) / UINT_MAX;
53
seed = seed*1664525 + 1013904223;
54
v-= ((double)seed) / UINT_MAX;
55
break
;
56
default
:
av_assert0
(0);
57
}
58
tmp[i] = v;
59
}
60
61
for
(i=0; i<
len
; i++){
62
double
v;
63
64
switch
(s->
dither_method
){
65
case
SWR_DITHER_RECTANGULAR
:
66
case
SWR_DITHER_TRIANGULAR
:
67
v = tmp[i];
68
break
;
69
case
SWR_DITHER_TRIANGULAR_HIGHPASS
:
70
v = (- tmp[i] + 2*tmp[i+1] - tmp[i+2]) / sqrt(6);
71
break
;
72
default
:
av_assert0
(0);
73
}
74
75
v*=
scale
;
76
77
switch
(in_fmt){
78
case
AV_SAMPLE_FMT_S16
: ((int16_t*)dst)[i] = v;
break
;
79
case
AV_SAMPLE_FMT_S32
: ((
int32_t
*)dst)[i] = v;
break
;
80
case
AV_SAMPLE_FMT_FLT
: ((
float
*)dst)[i] = v;
break
;
81
case
AV_SAMPLE_FMT_DBL
: ((
double
*)dst)[i] = v;
break
;
82
default
:
av_assert0
(0);
83
}
84
}
85
86
av_free
(tmp);
87
}
Generated on Sat May 25 2013 03:58:49 for FFmpeg by
1.8.2