1 /* 2 * Copyright (c) 2012 Justin Ruggles <justin.ruggles@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 #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 constraints for quantize() 41 int samples_align; ///< len constraints 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); 55 } DitherDSPContext; 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 */ 66 DitherContext *ff_dither_alloc(AVAudioResampleContext *avr, 67 enum AVSampleFormat out_fmt, 68 enum AVSampleFormat in_fmt, 69 int channels, int sample_rate, int apply_map); 70 71 /** 72 * Free a DitherContext. 73 * 74 * @param c DitherContext 75 */ 76 void ff_dither_free(DitherContext **c); 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 */ 86 int ff_convert_dither(DitherContext *c, AudioData *dst, AudioData *src); 87 88 /* arch-specific initialization functions */ 89 90 void ff_dither_init_x86(DitherDSPContext *ddsp, 91 enum AVResampleDitherMethod method); 92 93 #endif /* AVRESAMPLE_DITHER_H */ 94