quicktime/ffmpeg/libavcodec/mpegaudio.h

   1 /**
   2  * @file mpegaudio.h
   3  * mpeg audio declarations for both encoder and decoder.
   4  */
   5
   6 /* max frame size, in samples */
   7 #define MPA_FRAME_SIZE 1152
   8
   9 /* max compressed frame size */
  10 #define MPA_MAX_CODED_FRAME_SIZE 1792
  11
  12 #define MPA_MAX_CHANNELS 2
  13
  14 #define SBLIMIT 32 /* number of subbands */
  15
  16 #define MPA_STEREO  0
  17 #define MPA_JSTEREO 1
  18 #define MPA_DUAL    2
  19 #define MPA_MONO    3
  20
  21 /* header + layer + bitrate + freq + lsf/mpeg25 */
  22 #define SAME_HEADER_MASK \
  23    (0xffe00000 | (3 << 17) | (0xf << 12) | (3 << 10) | (3 << 19))
  24
  25 int l2_select_table(int bitrate, int nb_channels, int freq, int lsf);
  26 int mpa_decode_header(AVCodecContext *avctx, uint32_t head);
  27
  28 extern const uint16_t mpa_bitrate_tab[2][3][15];
  29 extern const uint16_t mpa_freq_tab[3];
  30 extern const unsigned char *alloc_tables[5];
  31 extern const double enwindow[512];
  32 extern const int sblimit_table[5];
  33 extern const int quant_steps[17];
  34 extern const int quant_bits[17];
  35 extern const int32_t mpa_enwindow[257];
  36
  37 /* fast header check for resync */
  38 static inline int ff_mpa_check_header(uint32_t header){
  39     /* header */
  40     if ((header & 0xffe00000) != 0xffe00000)
  41         return -1;
  42     /* layer check */
  43     if ((header & (3<<17)) == 0)
  44         return -1;
  45     /* bit rate */
  46     if ((header & (0xf<<12)) == 0xf<<12)
  47         return -1;
  48     /* frequency */
  49     if ((header & (3<<10)) == 3<<10)
  50         return -1;
  51     return 0;
  52 }