diff options
Diffstat (limited to 'src/spec.c')
| -rw-r--r-- | src/spec.c | 23 |
1 files changed, 13 insertions, 10 deletions
@@ -44,11 +44,12 @@ static int resolve_gain_offset(enum lc3_srate sr, int nbytes) * nbits_off Offset on the available bits, temporarily smoothed * g_off Gain index offset * reset_off Return True when the nbits_off must be reset + * g_min Return lower bound of quantized gain value * return The quantized gain value */ LC3_HOT static int estimate_gain( enum lc3_dt dt, enum lc3_srate sr, const float *x, - int nbits_budget, float nbits_off, int g_off, bool *reset_off) + int nbits_budget, float nbits_off, int g_off, bool *reset_off, int *g_min) { int ne = LC3_NE(dt, sr) >> 2; int e[LC3_MAX_NE]; @@ -102,12 +103,12 @@ LC3_HOT static int estimate_gain( /* --- Limit gain index --- */ - int g_min = x2_max == 0 ? -g_off : + *g_min = x2_max == 0 ? -g_off : ceilf(28 * log10f(sqrtf(x2_max) / (32768 - 0.375f))); - *reset_off = g_int < g_min || x2_max == 0; + *reset_off = g_int < *g_min || x2_max == 0; if (*reset_off) - g_int = g_min; + g_int = *g_min; return g_int; } @@ -118,10 +119,11 @@ LC3_HOT static int estimate_gain( * g_idx The estimated quantized gain index * nbits Computed number of bits coding the spectrum * nbits_budget Number of bits available for coding the spectrum + * g_idx_min Minimum gain index value * return Gain adjust value (-1 to 2) */ -LC3_HOT static int adjust_gain( - enum lc3_srate sr, int g_idx, int nbits, int nbits_budget) +LC3_HOT static int adjust_gain(enum lc3_srate sr, int g_idx, + int nbits, int nbits_budget, int g_idx_min) { /* --- Compute delta threshold --- */ @@ -149,7 +151,7 @@ LC3_HOT static int adjust_gain( /* --- Adjust gain --- */ if (nbits < nbits_budget - (delta + 2)) - return -(g_idx > 0); + return -(g_idx > g_idx_min); if (nbits > nbits_budget) return (g_idx < 255) + (g_idx < 254 && nbits >= nbits_budget + delta); @@ -789,8 +791,8 @@ void lc3_spec_analyze(enum lc3_dt dt, enum lc3_srate sr, int g_off = resolve_gain_offset(sr, nbytes); - int g_int = estimate_gain(dt, sr, - x, nbits_budget, nbits_off, g_off, &reset_off); + int g_min, g_int = estimate_gain(dt, sr, + x, nbits_budget, nbits_off, g_off, &reset_off, &g_min); /* --- Quantization --- */ @@ -803,7 +805,8 @@ void lc3_spec_analyze(enum lc3_dt dt, enum lc3_srate sr, /* --- Adjust gain and requantize --- */ - int g_adj = adjust_gain(sr, g_int + g_off, nbits, nbits_budget); + int g_adj = adjust_gain(sr, g_off + g_int, + nbits, nbits_budget, g_off + g_min); if (g_adj) quantize(dt, sr, g_adj, x, xq, &side->nq); |