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dither.h
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1 /*
2  * Copyright (c) 2012 Justin Ruggles <justin.ruggles@gmail.com>
3  *
4  * This file is part of Libav.
5  *
6  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #ifndef AVRESAMPLE_DITHER_H
22 #define AVRESAMPLE_DITHER_H
23 
24 #include "avresample.h"
25 #include "audio_data.h"
26 
27 typedef struct DitherContext DitherContext;
28 
29 typedef struct DitherDSPContext {
30  /**
31  * Convert samples from flt to s16 with added dither noise.
32  *
33  * @param dst destination float array, range -0.5 to 0.5
34  * @param src source int array, range INT_MIN to INT_MAX.
35  * @param dither float dither noise array
36  * @param len number of samples
37  */
38  void (*quantize)(int16_t *dst, const float *src, float *dither, int len);
39 
40  int ptr_align; ///< src and dst constraits for quantize()
41  int samples_align; ///< len constraits for quantize()
42 
43  /**
44  * Convert dither noise from int to float with triangular distribution.
45  *
46  * @param dst destination float array, range -0.5 to 0.5
47  * constraints: 32-byte aligned
48  * @param src0 source int array, range INT_MIN to INT_MAX.
49  * the array size is len * 2
50  * constraints: 32-byte aligned
51  * @param len number of output noise samples
52  * constraints: multiple of 16
53  */
54  void (*dither_int_to_float)(float *dst, int *src0, int len);
56 
57 /**
58  * Allocate and initialize a DitherContext.
59  *
60  * The parameters in the AVAudioResampleContext are used to initialize the
61  * DitherContext.
62  *
63  * @param avr AVAudioResampleContext
64  * @return newly-allocated DitherContext
65  */
67  enum AVSampleFormat out_fmt,
68  enum AVSampleFormat in_fmt,
69  int channels, int sample_rate);
70 
71 /**
72  * Free a DitherContext.
73  *
74  * @param c DitherContext
75  */
77 
78 /**
79  * Convert audio sample format with dithering.
80  *
81  * @param c DitherContext
82  * @param dst destination audio data
83  * @param src source audio data
84  * @return 0 if ok, negative AVERROR code on failure
85  */
87 
88 #endif /* AVRESAMPLE_DITHER_H */