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alac: factor out loading of next decoded sample in LPC prediction

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This commit is contained in:
Justin Ruggles 2012-07-09 12:57:16 -04:00
parent a4ecd41442
commit ebd4c3add1
1 changed files with 4 additions and 3 deletions
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7
libavcodec/alac.c
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@ -207,15 +207,16 @@ static void predictor_decompress_fir_adapt(int32_t *error_buffer,
int val = 0; int val = 0;
int error_val = error_buffer[i + 1]; int error_val = error_buffer[i + 1];
int error_sign; int error_sign;
int d = buffer_out[i - predictor_coef_num];
for (j = 0; j < predictor_coef_num; j++) { for (j = 0; j < predictor_coef_num; j++) {
val += (buffer_out[i - j] - buffer_out[i - predictor_coef_num]) * val += (buffer_out[i - j] - d) *
predictor_coef_table[j]; predictor_coef_table[j];
} }
val = (val + (1 << (predictor_quantitization - 1))) >> val = (val + (1 << (predictor_quantitization - 1))) >>
predictor_quantitization; predictor_quantitization;
val += buffer_out[i - predictor_coef_num] + error_val; val += d + error_val;
buffer_out[i + 1] = sign_extend(val, readsamplesize); buffer_out[i + 1] = sign_extend(val, readsamplesize);
@ -224,7 +225,7 @@ static void predictor_decompress_fir_adapt(int32_t *error_buffer,
if (error_sign) { if (error_sign) {
for (j = predictor_coef_num - 1; j >= 0 && error_val * error_sign > 0; j--) { for (j = predictor_coef_num - 1; j >= 0 && error_val * error_sign > 0; j--) {
int sign; int sign;
val = buffer_out[i - predictor_coef_num] - buffer_out[i - j]; val = d - buffer_out[i - j];
sign = sign_only(val) * error_sign; sign = sign_only(val) * error_sign;
predictor_coef_table[j] -= sign; predictor_coef_table[j] -= sign;
val *= sign; val *= sign;