diff options
Diffstat (limited to 'libavcodec/lsp.c')
| -rw-r--r-- | libavcodec/lsp.c | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/libavcodec/lsp.c b/libavcodec/lsp.c index fa7152737a..98ca490a76 100644 --- a/libavcodec/lsp.c +++ b/libavcodec/lsp.c @@ -117,6 +117,32 @@ void ff_acelp_lsp2lpc(int16_t* lp, const int16_t* lsp, int lp_half_order) } } +void ff_amrwb_lsp2lpc(const double *lsp, float *lp, int lp_order) +{ + int lp_half_order = lp_order >> 1; + double buf[lp_half_order + 1]; + double pa[lp_half_order + 1]; + double *qa = buf + 1; + int i,j; + + qa[-1] = 0.0; + + ff_lsp2polyf(lsp , pa, lp_half_order ); + ff_lsp2polyf(lsp + 1, qa, lp_half_order - 1); + + for (i = 1, j = lp_order - 1; i < lp_half_order; i++, j--) { + double paf = pa[i] * (1 + lsp[lp_order - 1]); + double qaf = (qa[i] - qa[i-2]) * (1 - lsp[lp_order - 1]); + lp[i-1] = (paf + qaf) * 0.5; + lp[j-1] = (paf - qaf) * 0.5; + } + + lp[lp_half_order - 1] = (1.0 + lsp[lp_order - 1]) * + pa[lp_half_order] * 0.5; + + lp[lp_order - 1] = lsp[lp_order - 1]; +} + void ff_acelp_lp_decode(int16_t* lp_1st, int16_t* lp_2nd, const int16_t* lsp_2nd, const int16_t* lsp_prev, int lp_order) { int16_t lsp_1st[MAX_LP_ORDER]; // (0.15) |