1 files changed, 121 insertions, 0 deletions
diff --git a/libao2/pl_extrastereo.c b/libao2/pl_extrastereo.c
new file mode 100644
index 0000000000..da15e0ff41
--- /dev/null
+++ b/libao2/pl_extrastereo.c
@@ -0,0 +1,121 @@
+/* Extrastereo effect plugin
+ * (linearly increases difference between L&R channels)
+ * 
+ * Current limitations:
+ *  - only AFMT_S16_LE is supported currently
+ *
+ * License: GPLv2 (as a mix of pl_volume.c and 
+ *          xmms:stereo_plugin/stereo.c)
+ * 
+ * Author: pl <p_l@gmx.fr> (c) 2002 and beyond...
+ * */
+
+#define PLUGIN
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <inttypes.h>
+
+#include "audio_out.h"
+#include "audio_plugin.h"
+#include "audio_plugin_internal.h"
+#include "afmt.h"
+
+static ao_info_t info = {
+        "Extra stereo plugin",
+        "extrastereo",
+        "pl <p_l@gmx.fr>",
+        ""
+};
+
+LIBAO_PLUGIN_EXTERN(extrastereo)
+
+// local data
+static struct {
+  float    mul;         // intensity
+  int      inuse;     	// This plugin is in use TRUE, FALSE
+  int      format;	// sample format
+} pl_extrastereo = {2.5, 0, 0};
+
+
+// to set/get/query special features/parameters
+static int control(int cmd,int arg){
+  switch(cmd){
+  case AOCONTROL_PLUGIN_SET_LEN:
+    return CONTROL_OK;
+  }
+  return CONTROL_UNKNOWN;
+}
+
+// open & setup audio device
+// return: 1=success 0=fail
+static int init(){
+  switch(ao_plugin_data.format){
+  case(AFMT_S16_LE):
+    break;
+  default:
+    fprintf(stderr,"[pl_extrastereo] Audio format not yet suported \n");
+    return 0;
+  }
+
+  pl_extrastereo.mul=ao_plugin_cfg.pl_extrastereo_mul;
+  pl_extrastereo.format=ao_plugin_data.format;
+  pl_extrastereo.inuse=1;
+
+  printf("[pl_extrastereo] Extra stereo plugin in use (multiplier=%2.2f).\n",
+           pl_extrastereo.mul);
+  return 1;
+}
+
+// close plugin
+static void uninit(){
+  pl_extrastereo.inuse=0;
+}
+
+// empty buffers
+static void reset(){
+}
+
+// processes 'ao_plugin_data.len' bytes of 'data'
+// called for every block of data
+static int play(){
+
+  switch(pl_extrastereo.format){
+  case(AFMT_S16_LE): {
+
+    int16_t* data=(int16_t*)ao_plugin_data.data;
+    int len=ao_plugin_data.len / 2; // 16 bits samples
+
+    float mul = pl_extrastereo.mul;
+    int32_t i, avg, ltmp, rtmp;
+
+    for (i=0; i < len ; i += 2) {
+
+      avg = (data[i] + data[i + 1]) / 2;
+
+      ltmp = avg + (int) (mul * (data[i] - avg));
+      rtmp = avg + (int) (mul * (data[i + 1] - avg));
+
+      if (ltmp < -32768) {
+        ltmp = -32768;
+      } else if (ltmp > 32767) {
+        ltmp = 32767;
+      }
+
+      if (rtmp < -32768) {
+        rtmp = -32768;
+      } else if (rtmp > 32767) {
+        rtmp = 32767;
+      }
+
+      data[i] = ltmp;
+      data[i + 1] = rtmp;
+    }
+    break;
+  }
+  default:
+    return 0;
+  }
+  return 1;
+}
+