-int ff_mpa_decode_header(AVCodecContext *avctx, uint32_t head, int *sample_rate);
-void ff_mpa_synth_init(MPA_INT *window);
-void ff_mpa_synth_filter(MPA_INT *synth_buf_ptr, int *synth_buf_offset,
- MPA_INT *window, int *dither_state,
- OUT_INT *samples, int incr,
- int32_t sb_samples[SBLIMIT]);
-
-/* fast header check for resync */
-static inline int ff_mpa_check_header(uint32_t header){
- /* header */
- if ((header & 0xffe00000) != 0xffe00000)
- return -1;
- /* layer check */
- if ((header & (3<<17)) == 0)
- return -1;
- /* bit rate */
- if ((header & (0xf<<12)) == 0xf<<12)
- return -1;
- /* frequency */
- if ((header & (3<<10)) == 3<<10)
- return -1;
- return 0;
-}