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improve the rice parameter calculation

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This commit is contained in:
Josh Coalson 2001-06-29 23:12:26 +00:00
parent 6ca4b1b2b2
commit 05d2079836
1 changed files with 8 additions and 9 deletions
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17
src/libFLAC/stream_encoder.c
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@ -1671,17 +1671,19 @@ FLAC__bool stream_encoder_set_partitioned_rice_(const FLAC__uint32 abs_residual[
else
partition_samples -= predictor_order;
}
mean = partition_samples >> 1;
#ifdef FLAC__PRECOMPUTE_PARTITION_SUMS
mean += abs_residual_partition_sums[partition];
mean = abs_residual_partition_sums[partition];
#else
mean = 0;
save_residual_sample = residual_sample;
for(partition_sample = 0; partition_sample < partition_samples; residual_sample++, partition_sample++)
mean += abs_residual[residual_sample];
residual_sample = save_residual_sample;
#endif
mean /= partition_samples;
#ifdef FLAC__SYMMETRIC_RICE
mean += partition_samples >> 1; /* for rounding effect */
mean /= partition_samples;
/* calc rice_parameter = floor(log2(mean)) */
rice_parameter = 0;
mean>>=1;
@ -1690,12 +1692,9 @@ FLAC__bool stream_encoder_set_partitioned_rice_(const FLAC__uint32 abs_residual[
mean >>= 1;
}
#else
/* calc rice_parameter = floor(log2(mean)) + 1 */
rice_parameter = 0;
while(mean) {
rice_parameter++;
mean >>= 1;
}
/* calc rice_parameter ala LOCO-I */
for(rice_parameter = 0; (partition_samples<<rice_parameter) < mean; rice_parameter++)
;
#endif
if(rice_parameter >= FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE_ESCAPE_PARAMETER)
rice_parameter = FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE_ESCAPE_PARAMETER - 1;