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  1. /*
  2.  * MLP codec common header file
  3.  * Copyright (c) 2007-2008 Ian Caulfield
  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. #ifndef AVCODEC_MLP_H
  23. #define AVCODEC_MLP_H
  24.  
  25. #include <stdint.h>
  26.  
  27. #include "avcodec.h"
  28.  
  29. /** Last possible matrix channel for each codec */
  30. #define MAX_MATRIX_CHANNEL_MLP      5
  31. #define MAX_MATRIX_CHANNEL_TRUEHD   7
  32. /** Maximum number of channels in a valid stream.
  33.  *  MLP   : 5.1 + 2 noise channels -> 8 channels
  34.  *  TrueHD: 7.1                    -> 8 channels
  35.  */
  36. #define MAX_CHANNELS                8
  37.  
  38. /** Maximum number of matrices used in decoding; most streams have one matrix
  39.  *  per output channel, but some rematrix a channel (usually 0) more than once.
  40.  */
  41. #define MAX_MATRICES_MLP            6
  42. #define MAX_MATRICES_TRUEHD         8
  43. #define MAX_MATRICES                8
  44.  
  45. /** Maximum number of substreams that can be decoded.
  46.  *  MLP's limit is 2. TrueHD supports at least up to 3.
  47.  */
  48. #define MAX_SUBSTREAMS      3
  49.  
  50. /** which multiple of 48000 the maximum sample rate is */
  51. #define MAX_RATEFACTOR      4
  52. /** maximum sample frequency seen in files */
  53. #define MAX_SAMPLERATE      (MAX_RATEFACTOR * 48000)
  54.  
  55. /** maximum number of audio samples within one access unit */
  56. #define MAX_BLOCKSIZE       (40 * MAX_RATEFACTOR)
  57. /** next power of two greater than MAX_BLOCKSIZE */
  58. #define MAX_BLOCKSIZE_POW2  (64 * MAX_RATEFACTOR)
  59.  
  60. /** number of allowed filters */
  61. #define NUM_FILTERS         2
  62.  
  63. /** The maximum number of taps in IIR and FIR filters. */
  64. #define MAX_FIR_ORDER       8
  65. #define MAX_IIR_ORDER       4
  66.  
  67. /** Code that signals end of a stream. */
  68. #define END_OF_STREAM       0xd234d234
  69.  
  70. #define FIR 0
  71. #define IIR 1
  72.  
  73. /** filter data */
  74. typedef struct FilterParams {
  75.     uint8_t     order; ///< number of taps in filter
  76.     uint8_t     shift; ///< Right shift to apply to output of filter.
  77.  
  78.     int32_t     state[MAX_FIR_ORDER];
  79. } FilterParams;
  80.  
  81. /** sample data coding information */
  82. typedef struct ChannelParams {
  83.     FilterParams filter_params[NUM_FILTERS];
  84.     int32_t     coeff[NUM_FILTERS][MAX_FIR_ORDER];
  85.  
  86.     int16_t     huff_offset;      ///< Offset to apply to residual values.
  87.     int32_t     sign_huff_offset; ///< sign/rounding-corrected version of huff_offset
  88.     uint8_t     codebook;         ///< Which VLC codebook to use to read residuals.
  89.     uint8_t     huff_lsbs;        ///< Size of residual suffix not encoded using VLC.
  90. } ChannelParams;
  91.  
  92. /** Tables defining the Huffman codes.
  93.  *  There are three entropy coding methods used in MLP (four if you count
  94.  *  "none" as a method). These use the same sequences for codes starting with
  95.  *  00 or 01, but have different codes starting with 1.
  96.  */
  97. extern const uint8_t ff_mlp_huffman_tables[3][18][2];
  98.  
  99. /** MLP uses checksums that seem to be based on the standard CRC algorithm, but
  100.  *  are not (in implementation terms, the table lookup and XOR are reversed).
  101.  *  We can implement this behavior using a standard av_crc on all but the
  102.  *  last element, then XOR that with the last element.
  103.  */
  104. uint8_t  ff_mlp_checksum8 (const uint8_t *buf, unsigned int buf_size);
  105. uint16_t ff_mlp_checksum16(const uint8_t *buf, unsigned int buf_size);
  106.  
  107. /** Calculate an 8-bit checksum over a restart header -- a non-multiple-of-8
  108.  *  number of bits, starting two bits into the first byte of buf.
  109.  */
  110. uint8_t ff_mlp_restart_checksum(const uint8_t *buf, unsigned int bit_size);
  111.  
  112. /** XOR together all the bytes of a buffer.
  113.  *  Does this belong in dspcontext?
  114.  */
  115. uint8_t ff_mlp_calculate_parity(const uint8_t *buf, unsigned int buf_size);
  116.  
  117. void ff_mlp_init_crc(void);
  118.  
  119. /** XOR four bytes into one. */
  120. static inline uint8_t xor_32_to_8(uint32_t value)
  121. {
  122.     value ^= value >> 16;
  123.     value ^= value >>  8;
  124.     return value;
  125. }
  126.  
  127. #endif /* AVCODEC_MLP_H */
  128.