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alac: use index into buffer_out instead of incrementing the pointer

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This commit is contained in:
Justin Ruggles 2012-07-09 12:52:30 -04:00
parent f2515cd629
commit a4ecd41442
1 changed files with 6 additions and 8 deletions
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14
libavcodec/alac.c
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@ -202,29 +202,29 @@ static void predictor_decompress_fir_adapt(int32_t *error_buffer,
/* NOTE: 4 and 8 are very common cases that could be optimized. */ /* NOTE: 4 and 8 are very common cases that could be optimized. */
/* general case */ /* general case */
for (i = predictor_coef_num + 1; i < output_size; i++) { for (i = predictor_coef_num; i < output_size - 1; i++) {
int j; int j;
int val = 0; int val = 0;
int error_val = error_buffer[i]; int error_val = error_buffer[i + 1];
int error_sign; int error_sign;
for (j = 0; j < predictor_coef_num; j++) { for (j = 0; j < predictor_coef_num; j++) {
val += (buffer_out[predictor_coef_num-j] - buffer_out[0]) * val += (buffer_out[i - j] - buffer_out[i - predictor_coef_num]) *
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[0] + error_val; val += buffer_out[i - predictor_coef_num] + error_val;
buffer_out[predictor_coef_num + 1] = sign_extend(val, readsamplesize); buffer_out[i + 1] = sign_extend(val, readsamplesize);
/* adapt LPC coefficients */ /* adapt LPC coefficients */
error_sign = sign_only(error_val); error_sign = sign_only(error_val);
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[0] - buffer_out[predictor_coef_num - j]; val = buffer_out[i - predictor_coef_num] - 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;
@ -232,8 +232,6 @@ static void predictor_decompress_fir_adapt(int32_t *error_buffer,
(predictor_coef_num - j)); (predictor_coef_num - j));
} }
} }
buffer_out++;
} }
} }