1 files changed, 66 insertions, 0 deletions
diff --git a/dxr3audio.c b/dxr3audio.c
new file mode 100644
index 0000000..e2daa71
--- /dev/null
+++ b/dxr3audio.c
@@ -0,0 +1,66 @@
+/*
+ * dxr3audio.c
+ *
+ * Copyright (C) 2009 Christian Gmeiner
+ *
+ * This program 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.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ */
+
+#include <string.h>     // for memeset
+#include <math.h>       // for pow
+#include <vdr/device.h> // for MAXVOLUME
+
+#include "dxr3audio.h"
+
+const static int AUDIO_STEREO = 0;
+const static int AUDIO_MONO_LEFT = 1;
+const static int AUDIO_MONO_RIGHT = 2;
+
+void iAudio::changeVolume(int16_t* pcmbuf, size_t size) {
+
+    if (vol == 0) {
+	    memset(pcmbuf, 0, size);
+    } else if (vol < MAXVOLUME) {
+
+	    int factor = (int)(pow(10.0, -2.5 + 2.5*vol/256.0)*0x7FFF);
+        size = size / 2;
+
+        while (size > 0) {
+            register int32_t tmp = (int32_t)(*pcmbuf) * factor;
+            *pcmbuf = (int16_t) (tmp>>15);
+            pcmbuf++;
+            size--;
+        }
+
+        // respect audio channel setting
+        if (audioChannel == AUDIO_STEREO)
+        	return;
+
+        if (audioChannel == AUDIO_MONO_RIGHT) {
+
+        	for (unsigned int i = 0; i < size / sizeof(short); i++) {
+        		if (!(i & 0x1))
+        			pcmbuf[i] = pcmbuf[i+1];
+        	}
+        } else if (audioChannel == AUDIO_MONO_LEFT) {
+
+           	for (unsigned int i = 0; i < size / sizeof(short); i++) {
+           		if ((i & 0x1))
+           			pcmbuf[i] = pcmbuf[i-1];
+           	}
+        }
+    }
+}