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  1. /*
  2.  * ADX ADPCM codecs
  3.  * Copyright (c) 2001,2003 BERO
  4.  *
  5.  * This file is part of FFmpeg.
  6.  *
  7.  * FFmpeg is free software; you can redistribute it and/or
  8.  * modify it under the terms of the GNU Lesser General Public
  9.  * License as published by the Free Software Foundation; either
  10.  * version 2.1 of the License, or (at your option) any later version.
  11.  *
  12.  * FFmpeg is distributed in the hope that it will be useful,
  13.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15.  * Lesser General Public License for more details.
  16.  *
  17.  * You should have received a copy of the GNU Lesser General Public
  18.  * License along with FFmpeg; if not, write to the Free Software
  19.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20.  */
  21.  
  22. /**
  23.  * @file
  24.  * SEGA CRI adx codecs.
  25.  *
  26.  * Reference documents:
  27.  * http://ku-www.ss.titech.ac.jp/~yatsushi/adx.html
  28.  * adx2wav & wav2adx http://www.geocities.co.jp/Playtown/2004/
  29.  */
  30.  
  31. #ifndef AVCODEC_ADX_H
  32. #define AVCODEC_ADX_H
  33.  
  34. #include <stdint.h>
  35.  
  36. #include "avcodec.h"
  37.  
  38. typedef struct ADXChannelState {
  39.     int s1,s2;
  40. } ADXChannelState;
  41.  
  42. typedef struct ADXContext {
  43.     int channels;
  44.     ADXChannelState prev[2];
  45.     int header_parsed;
  46.     int eof;
  47.     int cutoff;
  48.     int coeff[2];
  49. } ADXContext;
  50.  
  51. #define COEFF_BITS  12
  52.  
  53. #define BLOCK_SIZE      18
  54. #define BLOCK_SAMPLES   32
  55.  
  56. /**
  57.  * Calculate LPC coefficients based on cutoff frequency and sample rate.
  58.  *
  59.  * @param cutoff       cutoff frequency
  60.  * @param sample_rate  sample rate
  61.  * @param bits         number of bits used to quantize coefficients
  62.  * @param[out] coeff   2 quantized LPC coefficients
  63.  */
  64. void ff_adx_calculate_coeffs(int cutoff, int sample_rate, int bits, int *coeff);
  65.  
  66. /**
  67.  * Decode ADX stream header.
  68.  * Sets avctx->channels and avctx->sample_rate.
  69.  *
  70.  * @param      avctx        codec context
  71.  * @param      buf          header data
  72.  * @param      bufsize      data size, should be at least 24 bytes
  73.  * @param[out] header_size  size of ADX header
  74.  * @param[out] coeff        2 LPC coefficients, can be NULL
  75.  * @return data offset or negative error code if header is invalid
  76.  */
  77. int avpriv_adx_decode_header(AVCodecContext *avctx, const uint8_t *buf,
  78.                              int bufsize, int *header_size, int *coeff);
  79.  
  80. #endif /* AVCODEC_ADX_H */
  81.