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ffmpeg / libavcodec / mpegaudio.h @ 71160c55

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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);
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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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}