mirror of
https://github.com/FFmpeg/FFmpeg.git
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53 lines
1.4 KiB
C
53 lines
1.4 KiB
C
/**
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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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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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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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