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ffmpeg / libavcodec / mlp.h @ ce15710f

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/*
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 * MLP codec common header file
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 * Copyright (c) 2007-2008 Ian Caulfield
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 *
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 * This file is part of FFmpeg.
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 *
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 * FFmpeg is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * FFmpeg is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with FFmpeg; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
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#ifndef FFMPEG_MLP_H
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#define FFMPEG_MLP_H
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#include <stdint.h>
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#include "avcodec.h"
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/** Maximum number of channels that can be decoded. */
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#define MAX_CHANNELS        16
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/** Maximum number of matrices used in decoding; most streams have one matrix
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 *  per output channel, but some rematrix a channel (usually 0) more than once.
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 */
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#define MAX_MATRICES        15
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/** Maximum number of substreams that can be decoded. This could also be set
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 *  higher, but I haven't seen any examples with more than two. */
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#define MAX_SUBSTREAMS      2
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/** maximum sample frequency seen in files */
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#define MAX_SAMPLERATE      192000
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/** maximum number of audio samples within one access unit */
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#define MAX_BLOCKSIZE       (40 * (MAX_SAMPLERATE / 48000))
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/** next power of two greater than MAX_BLOCKSIZE */
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#define MAX_BLOCKSIZE_POW2  (64 * (MAX_SAMPLERATE / 48000))
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/** number of allowed filters */
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#define NUM_FILTERS         2
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/** The maximum number of taps in either the IIR or FIR filter;
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 *  I believe MLP actually specifies the maximum order for IIR filters as four,
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 *  and that the sum of the orders of both filters must be <= 8. */
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#define MAX_FILTER_ORDER    8
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#define FIR 0
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#define IIR 1
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/** filter data */
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typedef struct {
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    uint8_t     order; ///< number of taps in filter
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    uint8_t     shift; ///< Right shift to apply to output of filter.
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    int32_t     coeff[MAX_FILTER_ORDER];
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    int32_t     state[MAX_FILTER_ORDER];
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} FilterParams;
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/** sample data coding information */
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typedef struct {
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    FilterParams filter_params[NUM_FILTERS];
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    int16_t     huff_offset;      ///< Offset to apply to residual values.
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    int32_t     sign_huff_offset; ///< sign/rounding-corrected version of huff_offset
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    uint8_t     codebook;         ///< Which VLC codebook to use to read residuals.
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    uint8_t     huff_lsbs;        ///< Size of residual suffix not encoded using VLC.
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} ChannelParams;
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/** Tables defining the Huffman codes.
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 *  There are three entropy coding methods used in MLP (four if you count
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 *  "none" as a method). These use the same sequences for codes starting with
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 *  00 or 01, but have different codes starting with 1. */
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extern const uint8_t ff_mlp_huffman_tables[3][18][2];
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/** MLP uses checksums that seem to be based on the standard CRC algorithm, but
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 *  are not (in implementation terms, the table lookup and XOR are reversed).
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 *  We can implement this behavior using a standard av_crc on all but the
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 *  last element, then XOR that with the last element. */
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uint8_t  ff_mlp_checksum8 (const uint8_t *buf, unsigned int buf_size);
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uint16_t ff_mlp_checksum16(const uint8_t *buf, unsigned int buf_size);
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/** Calculate an 8-bit checksum over a restart header -- a non-multiple-of-8
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 *  number of bits, starting two bits into the first byte of buf. */
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uint8_t ff_mlp_restart_checksum(const uint8_t *buf, unsigned int bit_size);
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/** XOR together all the bytes of a buffer.
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 *  Does this belong in dspcontext? */
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uint8_t ff_mlp_calculate_parity(const uint8_t *buf, unsigned int buf_size);
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int ff_mlp_init_crc2D(AVCodecParserContext *s);
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void ff_mlp_init_crc();
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#endif /* FFMPEG_MLP_H */