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* Copyright (c) 2012 Justin Ruggles <>
* 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
* 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
#include "avresample.h"
#include "audio_data.h"
typedef struct DitherContext DitherContext;
typedef struct DitherDSPContext {
* Convert samples from flt to s16 with added dither noise.
* @param dst destination float array, range -0.5 to 0.5
* @param src source int array, range INT_MIN to INT_MAX.
* @param dither float dither noise array
* @param len number of samples
void (*quantize)(int16_t *dst, const float *src, float *dither, int len);
int ptr_align; ///< src and dst constraits for quantize()
int samples_align; ///< len constraits for quantize()
* Convert dither noise from int to float with triangular distribution.
* @param dst destination float array, range -0.5 to 0.5
* constraints: 32-byte aligned
* @param src0 source int array, range INT_MIN to INT_MAX.
* the array size is len * 2
* constraints: 32-byte aligned
* @param len number of output noise samples
* constraints: multiple of 16
void (*dither_int_to_float)(float *dst, int *src0, int len);
} DitherDSPContext;
* Allocate and initialize a DitherContext.
* The parameters in the AVAudioResampleContext are used to initialize the
* DitherContext.
* @param avr AVAudioResampleContext
* @return newly-allocated DitherContext
DitherContext *ff_dither_alloc(AVAudioResampleContext *avr,
enum AVSampleFormat out_fmt,
enum AVSampleFormat in_fmt,
int channels, int sample_rate, int apply_map);
* Free a DitherContext.
* @param c DitherContext
void ff_dither_free(DitherContext **c);
* Convert audio sample format with dithering.
* @param c DitherContext
* @param dst destination audio data
* @param src source audio data
* @return 0 if ok, negative AVERROR code on failure
int ff_convert_dither(DitherContext *c, AudioData *dst, AudioData *src);
/* arch-specific initialization functions */
void ff_dither_init_x86(DitherDSPContext *ddsp,
enum AVResampleDitherMethod method);
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