Improve LPC order guess
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.
Signed-off-by: Erik de Castro Lopo <erikd@mega-nerd.com>
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__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 @@
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);