1 files changed, 57 insertions, 0 deletions
diff --git a/media/libmedia/mediaplayer.cpp b/media/libmedia/mediaplayer.cpp
index aeb43c5..040366b 100644
--- a/media/libmedia/mediaplayer.cpp
+++ b/media/libmedia/mediaplayer.cpp
@@ -690,4 +690,61 @@ MediaPlayer::DeathNotifier::~DeathNotifier()
 
 }
 
+extern "C" {
+#define FLOATING_POINT 1
+#include "fftwrap.h"
+}
+
+static void *ffttable = NULL;
+
+// peeks at the audio data and fills 'data' with the requested kind
+// (currently kind=0 returns mono 16 bit PCM data, and kind=1 returns
+// 256 point FFT data). Return value is number of samples returned,
+// which may be 0.
+/*static*/ int MediaPlayer::snoop(short* data, int len, int kind) {
+
+    sp<IMemory> p;
+    const sp<IMediaPlayerService>& service = getMediaPlayerService();
+    if (service != 0) {
+        // Take a peek at the waveform. The returned data consists of 16 bit mono PCM data.
+        p = service->snoop();
+
+        if (p == NULL) {
+            return 0;
+        }
+
+        if (kind == 0) { // return waveform data
+            int plen = p->size();
+            len *= 2; // number of shorts -> number of bytes
+            short *src = (short*) p->pointer();
+            if (plen > len) {
+                plen = len;
+            }
+            memcpy(data, src, plen);
+            return plen / sizeof(short); // return number of samples
+        } else if (kind == 1) {
+            // TODO: use a more efficient FFT
+            // Right now this uses the speex library, which is compiled to do a float FFT
+            if (!ffttable) ffttable = spx_fft_init(512);
+            short *usrc = (short*) p->pointer();
+            float fsrc[512];
+            for (int i=0;i<512;i++)
+                fsrc[i] = usrc[i];
+            float fdst[512];
+            spx_fft_float(ffttable, fsrc, fdst);
+            if (len > 512) {
+                len = 512;
+            }
+            len /= 2; // only half the output data is valid
+            for (int i=0; i < len; i++)
+                data[i] = fdst[i];
+            return len;
+        }
+
+    } else {
+        LOGE("Unable to locate media service");
+    }
+    return 0;
+}
+
 }; // namespace android