ffmpeg / libavcodec / mlp.h @ ce15710f
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/*


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* MLP codec common header file

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* Copyright (c) 20072008 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 021101301 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/roundingcorrected 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 8bit checksum over a restart header  a nonmultipleof8

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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 */ 