flac_filter_1.diff

Index: mlpenc.c
===================================================================
--- mlpenc.c	(revision 3116)
+++ mlpenc.c	(working copy)
@@ -22,6 +22,7 @@
 #include "avcodec.h"
 #include "bitstream.h"
 #include "libavutil/crc.h"
+#include "dsputil.h"
 
 /* TODO add comments! */
 
@@ -107,6 +108,8 @@
 
     DecodingParams  decoding_params[MAX_SUBSTREAMS];
     RestartHeader   restart_header[MAX_SUBSTREAMS];
+
+    DSPContext      dsp;
 } MLPEncodeContext;
 
 #define SYNC_MAJOR      0xf8726f
@@ -290,6 +293,8 @@
 
     ctx->avctx = avctx;
 
+    dsputil_init(&ctx->dsp, avctx);
+
     ctx->sample_rate = mlp_sample_rate(avctx->sample_rate);
     if (ctx->sample_rate < 0) {
         av_log(avctx, AV_LOG_ERROR, "Unsupported sample_rate.\n");
@@ -555,20 +560,49 @@
     }
 }
 
+#define ORDER_METHOD_EST     0
+#define ORDER_METHOD_2LEVEL  1
+#define ORDER_METHOD_4LEVEL  2
+#define ORDER_METHOD_8LEVEL  3
+#define ORDER_METHOD_SEARCH  4
+#define ORDER_METHOD_LOG     5
+
+#define MAX_LPC_ORDER      32
+
+/**
+ * Calculate LPC coefficients for multiple orders
+ */
+int ff_lpc_calc_coefs(DSPContext *dsp,
+                          const int32_t *samples, int blocksize, int max_order,
+                          int precision, int32_t coefs[][MAX_LPC_ORDER],
+                          int *shift, int use_lpc, int omethod);
+
 static void set_filter_params(MLPEncodeContext *ctx,
                               unsigned int channel, unsigned int filter)
 {
     FilterParams *fp = &ctx->filter_params[channel][filter];
 
     if (filter == FIR) {
-        fp->order    =  4;
-        fp->shift    =  0;
-        fp->coeff[0] =  1;
-        fp->coeff[1] =  0;
-        fp->coeff[2] =  0;
-        fp->coeff[3] =  0;
+        int32_t coefs[MAX_LPC_ORDER][MAX_LPC_ORDER];
+        int32_t samples[MAX_BLOCKSIZE];
+        int shift[MAX_FILTER_ORDER];
+        int order;
+        int i;
+
+        for (i = 0; i < ctx->avctx->frame_size; i++)
+            samples[i] = ctx->sample_buffer[i][channel];
+
+        order = ff_lpc_calc_coefs(&ctx->dsp, samples, ctx->avctx->frame_size,
+                                  8, 9, coefs, shift, 1, ORDER_METHOD_EST);
+
+        fp->order = order;
+        fp->shift = shift[order-1];
+
+        for (i = 0; i < order; i++)
+            fp->coeff[i] = coefs[order-1][i];
+
     } else { /* IIR */
-        fp->order    =  4;
+        fp->order    =  0;
         fp->shift    =  0;
         fp->coeff[0] =  0;
         fp->coeff[1] =  0;