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https://git.ffmpeg.org/ffmpeg.git
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107 lines
3.2 KiB
C
107 lines
3.2 KiB
C
/*
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* copyright (c) 2001 Fabrice Bellard
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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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/**
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* @file mpegaudio.h
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* mpeg audio declarations for both encoder and decoder.
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*/
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/* max frame size, in samples */
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#define MPA_FRAME_SIZE 1152
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/* max compressed frame size */
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#define MPA_MAX_CODED_FRAME_SIZE 1792
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#define MPA_MAX_CHANNELS 2
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#define SBLIMIT 32 /* number of subbands */
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#define MPA_STEREO 0
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#define MPA_JSTEREO 1
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#define MPA_DUAL 2
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#define MPA_MONO 3
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/* header + layer + bitrate + freq + lsf/mpeg25 */
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#define SAME_HEADER_MASK \
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(0xffe00000 | (3 << 17) | (0xf << 12) | (3 << 10) | (3 << 19))
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/* define USE_HIGHPRECISION to have a bit exact (but slower) mpeg
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audio decoder */
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#ifdef USE_HIGHPRECISION
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#define FRAC_BITS 23 /* fractional bits for sb_samples and dct */
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#define WFRAC_BITS 16 /* fractional bits for window */
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#else
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#define FRAC_BITS 15 /* fractional bits for sb_samples and dct */
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#define WFRAC_BITS 14 /* fractional bits for window */
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#endif
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#if defined(USE_HIGHPRECISION) && defined(CONFIG_AUDIO_NONSHORT)
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typedef int32_t OUT_INT;
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#define OUT_MAX INT32_MAX
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#define OUT_MIN INT32_MIN
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#define OUT_SHIFT (WFRAC_BITS + FRAC_BITS - 31)
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#else
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typedef int16_t OUT_INT;
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#define OUT_MAX INT16_MAX
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#define OUT_MIN INT16_MIN
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#define OUT_SHIFT (WFRAC_BITS + FRAC_BITS - 15)
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#endif
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#if FRAC_BITS <= 15
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typedef int16_t MPA_INT;
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#else
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typedef int32_t MPA_INT;
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#endif
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int l2_select_table(int bitrate, int nb_channels, int freq, int lsf);
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int mpa_decode_header(AVCodecContext *avctx, uint32_t head, int *sample_rate);
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void ff_mpa_synth_init(MPA_INT *window);
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void ff_mpa_synth_filter(MPA_INT *synth_buf_ptr, int *synth_buf_offset,
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MPA_INT *window, int *dither_state,
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OUT_INT *samples, int incr,
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int32_t sb_samples[SBLIMIT]);
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extern const uint16_t mpa_bitrate_tab[2][3][15];
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extern const uint16_t mpa_freq_tab[3];
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extern const unsigned char *alloc_tables[5];
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extern const double enwindow[512];
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extern const int sblimit_table[5];
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extern const int quant_steps[17];
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extern const int quant_bits[17];
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extern const int32_t mpa_enwindow[257];
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/* fast header check for resync */
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static inline int ff_mpa_check_header(uint32_t header){
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/* header */
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if ((header & 0xffe00000) != 0xffe00000)
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return -1;
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/* layer check */
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if ((header & (3<<17)) == 0)
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return -1;
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/* bit rate */
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if ((header & (0xf<<12)) == 0xf<<12)
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return -1;
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/* frequency */
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if ((header & (3<<10)) == 3<<10)
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return -1;
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return 0;
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}
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