From b2fe6756e34d1316d0fa799e8a5ace993059c407 Mon Sep 17 00:00:00 2001 From: Justin Ruggles Date: Wed, 31 Oct 2012 15:40:12 -0400 Subject: lavr: add option for dithering during sample format conversion to s16 --- libavresample/dither.h | 88 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 88 insertions(+) create mode 100644 libavresample/dither.h (limited to 'libavresample/dither.h') diff --git a/libavresample/dither.h b/libavresample/dither.h new file mode 100644 index 0000000000..8b30dd23e0 --- /dev/null +++ b/libavresample/dither.h @@ -0,0 +1,88 @@ +/* + * Copyright (c) 2012 Justin Ruggles + * + * This file is part of Libav. + * + * Libav 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. + * + * Libav is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with Libav; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#ifndef AVRESAMPLE_DITHER_H +#define AVRESAMPLE_DITHER_H + +#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); + +/** + * 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); + +#endif /* AVRESAMPLE_DITHER_H */ -- cgit v1.2.3