Split synth filter out of dca.c.

Originally committed as revision 20396 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 56 insertions, 0 deletions

diff --git a/libavcodec/synth_filter.c b/libavcodec/synth_filter.c
new file mode 100644
index 0000000000..3df1a2a8a2
--- /dev/null
+++ b/libavcodec/synth_filter.c
@@ -0,0 +1,56 @@
+/*
+ * copyright (c) 2008 Michael Niedermayer <michaelni@gmx.at>
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "synth_filter.h"
+
+void ff_synth_filter_float(FFTContext *imdct,
+                         float *synth_buf_ptr, int *synth_buf_offset,
+                         float synth_buf2[32], const float window[512],
+                         float out[32], const float in[32], float scale, float bias)
+{
+    float *synth_buf= synth_buf_ptr + *synth_buf_offset;
+    int i, j;
+
+    ff_imdct_half(imdct, synth_buf, in);
+
+    for (i = 0; i < 16; i++){
+        float a= synth_buf2[i   ];
+        float b= synth_buf2[i+16];
+        float c= 0;
+        float d= 0;
+        for (j = 0; j < 512 - *synth_buf_offset; j += 64){
+            a += window[i+j   ]*(-synth_buf[15-i+j]);
+            b += window[i+j+16]*( synth_buf[   i+j]);
+            c += window[i+j+32]*( synth_buf[16+i+j]);
+            d += window[i+j+48]*( synth_buf[31-i+j]);
+        }
+        for (     ; j < 512; j += 64){
+            a += window[i+j   ]*(-synth_buf[15-i+j-512]);
+            b += window[i+j+16]*( synth_buf[   i+j-512]);
+            c += window[i+j+32]*( synth_buf[16+i+j-512]);
+            d += window[i+j+48]*( synth_buf[31-i+j-512]);
+        }
+        out[i   ] = a * scale + bias;
+        out[i+16] = b * scale + bias;
+        synth_buf2[i   ] = c;
+        synth_buf2[i+16] = d;
+    }
+    *synth_buf_offset= (*synth_buf_offset-32)&511;
+}