lpc: use levinson for the first pass of multipass cholesky

Levinson is faster, and cholesky is only needed if we want to apply different
weights to different samples, which doesn't happen on the first pass.

Signed-off-by: Luca Barbato <lu_zero@gentoo.org>

diff --git a/libavcodec/lpc.c b/libavcodec/lpc.c
index 144bbede44a21d3c7806deb6ef58c47697c4465e..995e4e2ad4408ee4ca0145e6eb4a887aa0fc5f47 100644 (file)
--- a/libavcodec/lpc.c
+++ b/libavcodec/lpc.c
@@ -176,7 +176,7 @@ int ff_lpc_calc_coefs(LPCContext *s,
     double autoc[MAX_LPC_ORDER+1];
     double ref[MAX_LPC_ORDER];
     double lpc[MAX_LPC_ORDER][MAX_LPC_ORDER];
-    int i, j, pass;
+    int i, j, pass = 0;
     int opt_order;
 
     assert(max_order >= MIN_LPC_ORDER && max_order <= MAX_LPC_ORDER &&
@@ -189,7 +189,7 @@ int ff_lpc_calc_coefs(LPCContext *s,
         ff_lpc_init(s, blocksize, max_order, lpc_type);
     }
 
-    if (lpc_type == FF_LPC_TYPE_LEVINSON) {
+    if (lpc_type == FF_LPC_TYPE_LEVINSON || (lpc_type == FF_LPC_TYPE_CHOLESKY && lpc_passes > 1)) {
         s->lpc_apply_welch_window(samples, blocksize, s->windowed_samples);
 
         s->lpc_compute_autocorr(s->windowed_samples, blocksize, max_order, autoc);
@@ -198,13 +198,20 @@ int ff_lpc_calc_coefs(LPCContext *s,
 
         for(i=0; i<max_order; i++)
             ref[i] = fabs(lpc[i][i]);
-    } else if (lpc_type == FF_LPC_TYPE_CHOLESKY) {
+
+        pass++;
+    }
+
+    if (lpc_type == FF_LPC_TYPE_CHOLESKY) {
         LLSModel m[2];
         LOCAL_ALIGNED(32, double, var, [FFALIGN(MAX_LPC_ORDER+1,4)]);
         double av_uninit(weight);
         memset(var, 0, FFALIGN(MAX_LPC_ORDER+1,4)*sizeof(*var));
 
-        for(pass=0; pass<lpc_passes; pass++){
+        for(j=0; j<max_order; j++)
+            m[0].coeff[max_order-1][j] = -lpc[max_order-1][j];
+
+        for(; pass<lpc_passes; pass++){
             avpriv_init_lls(&m[pass&1], max_order);
 
             weight=0;
@@ -259,15 +266,11 @@ av_cold int ff_lpc_init(LPCContext *s, int blocksize, int max_order,
     s->max_order = max_order;
     s->lpc_type  = lpc_type;
 
-    if (lpc_type == FF_LPC_TYPE_LEVINSON) {
-        s->windowed_buffer = av_mallocz((blocksize + 2 + FFALIGN(max_order, 4)) *
-                                        sizeof(*s->windowed_samples));
-        if (!s->windowed_buffer)
-            return AVERROR(ENOMEM);
-        s->windowed_samples = s->windowed_buffer + FFALIGN(max_order, 4);
-    } else {
-        s->windowed_samples = NULL;
-    }
+    s->windowed_buffer = av_mallocz((blocksize + 2 + FFALIGN(max_order, 4)) *
+                                    sizeof(*s->windowed_samples));
+    if (!s->windowed_buffer)
+        return AVERROR(ENOMEM);
+    s->windowed_samples = s->windowed_buffer + FFALIGN(max_order, 4);
 
     s->lpc_apply_welch_window = lpc_apply_welch_window_c;
     s->lpc_compute_autocorr   = lpc_compute_autocorr_c;