1 files changed, 43 insertions, 0 deletions
diff --git a/media/audio/simple_sources.cc b/media/audio/simple_sources.cc
new file mode 100644
index 0000000..b6fda23
--- /dev/null
+++ b/media/audio/simple_sources.cc
@@ -0,0 +1,43 @@
+// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <math.h>
+
+#include "base/basictypes.h"
+#include "base/logging.h"
+#include "media/audio/audio_output.h"
+#include "media/audio/simple_sources.h"
+
+SineWaveAudioSource::SineWaveAudioSource(Format format, int channels,
+                                         double freq, double sample_freq)
+    : format_(format),
+      channels_(channels),
+      freq_(freq),
+      sample_freq_(sample_freq) {
+  // TODO(cpu): support other formats.
+  DCHECK((format_ == FORMAT_16BIT_LINEAR_PCM) && (channels_ == 1));
+}
+
+// The implementation could be more efficient if a lookup table is constructed
+// but it is efficient enough for our simple needs.
+size_t SineWaveAudioSource::OnMoreData(AudioOutputStream* stream,
+                                       void* dest, size_t max_size) {
+  const double kTwoPi = 2.0 * 3.141592653589;
+  double f = freq_ / sample_freq_;
+  int16* sin_tbl = reinterpret_cast<int16*>(dest);
+  size_t len = max_size / sizeof(int16);
+  // The table is filled with s(t) = 32768*sin(2PI*f*t).
+  for (size_t ix = 0; ix != len; ++ix) {
+    double th = kTwoPi * ix * f;
+    sin_tbl[ix] = static_cast<int16>((1 << 15) * sin(th));
+  }
+  return max_size;
+}
+
+void SineWaveAudioSource::OnClose(AudioOutputStream* stream) {
+}
+
+void SineWaveAudioSource::OnError(AudioOutputStream* stream, int code) {
+  NOTREACHED();
+}