[PATCH] Improve LPC order guess

[Martijn van Beurden]

The recent compression preset retuning improved upon most material
but it the few tracks that show regression are usually classical
music. This patch improves compression by improving the LPC order
guess, of which classical music benefits most.

Improvement is 0.007% on average but up to 0.1%. I haven't seen
regressions for any of my test samples.
---
 src/libFLAC/lpc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/libFLAC/lpc.c b/src/libFLAC/lpc.c
index ca98c5c..f7c643a 100644
--- a/src/libFLAC/lpc.c
+++ b/src/libFLAC/lpc.c
@@ -1308,7 +1308,7 @@ FLAC__double FLAC__lpc_compute_expected_bits_per_residual_sample(FLAC__double lp
 
 	FLAC__ASSERT(total_samples > 0);
 
-	error_scale = 0.5 * M_LN2 * M_LN2 / (FLAC__double)total_samples;
+	error_scale = 0.5 / (FLAC__double)total_samples;
 
 	return FLAC__lpc_compute_expected_bits_per_residual_sample_with_error_scale(lpc_error, error_scale);
 }
@@ -1338,7 +1338,7 @@ unsigned FLAC__lpc_compute_best_order(const FLAC__double lpc_error[], unsigned m
 	FLAC__ASSERT(max_order > 0);
 	FLAC__ASSERT(total_samples > 0);
 
-	error_scale = 0.5 * M_LN2 * M_LN2 / (FLAC__double)total_samples;
+	error_scale = 0.5 / (FLAC__double)total_samples;
 
 	best_index = 0;
 	best_bits = (unsigned)(-1);
-- 
1.9.1


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