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fix: Gain adjustment during second quantization phase can exceed minimum gain

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This commit is contained in:
Antoine Soulier
2023-07-25 10:49:55 -07:00
parent 3b23884611
commit 67f2231815
3 changed files with 23 additions and 19 deletions
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23
src/spec.c
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@@ -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);