AudioHandler, AudioInput, Opus ecoder code in place.

16 files changed, 639 insertions, 14 deletions

diff --git a/.gitignore b/.gitignore
index 50ea780..1552af3 100644
--- a/.gitignore
+++ b/.gitignore
@@ -22,3 +22,4 @@ missing
 qrc_*
 src/simplertp
 stamp-h1
+test-driver
\ No newline at end of file
diff --git a/configure.ac b/configure.ac
index 00f54d1..36978fd 100644
--- a/configure.ac
+++ b/configure.ac
@@ -45,10 +45,15 @@ if (test "$QT_UIC" = ""); then
   AC_MSG_ERROR([QT4 uic is required.])
 fi
 
-#dnl ======================
-#dnl Check for libao
-#dnl ======================
-#PKG_CHECK_MODULES(AO, ao >= 0.8.8)
+dnl ======================
+dnl Check for libao
+dnl ======================
+PKG_CHECK_MODULES(AO, ao >= 0.8.8)
+
+dnl ======================
+dnl Check for opus
+dnl ======================
+PKG_CHECK_MODULES(OPUS, opus >= 1.0.2)
 
 dnl ======================
 dnl Check for Jpeg library
diff --git a/src/Makefile.am b/src/Makefile.am
index e407edc..1b457ca 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -1,21 +1,37 @@
 bin_PROGRAMS = simplertp
 
 simplertp_LDADD = $(QT_LIBS) $(AO_LIBS) $(V4LC_LIBS) -ljpeg \
-	$(top_srcdir)/lrtp/src/liblrtp.la $(top_srcdir)/libaudioin/src/libaudioin.la \
+	$(OPUS_LIBS) $(AO_LIBS) \
+	$(top_srcdir)/lrtp/src/liblrtp.la \
+	$(top_srcdir)/libaudioin/src/libaudioin.la \
 	$(shell ../tools/MocList o ) qrc_simplertp.o 
 
-simplertp_CXXFLAGS = $(QT_CFLAGS) $(AO_CFLAGS) $(V4LC_CFLAGS)
-AM_CXXFLAGS = $(QT_CFLAGS)
+simplertp_CXXFLAGS = $(QT_CFLAGS) $(AO_CFLAGS) $(V4LC_CFLAGS) \
+	-I$(top_srcdir)/lrtp/src \
+	-I$(top_srcdir)/libaudioin/src \
+	$(OPUS_CFLAGS) $(AO_CFLAGS)
+
+AM_CXXFLAGS = $(simplertp_CXXFLAGS)
 
 simplertp_SOURCES = \
 	simplertp.cc \
 	mainwindow.cc \
-	v4l.cc
+	v4l.cc \
+	opusencoder.cc \
+	samplecache.cc \
+	frame.cc \
+	audioinput.cc \
+	audiohandler.cc
 
 EXTRA_DIST = \
 	simplertp.qrc
 	mainwindow.h \
-	v4l.h
+	v4l.h \
+	opusencoder.h \
+	samplecache.h \
+	frame.h \
+	audioinput.h \
+	audiohandler.h
 
 simplertp_MOC = $(shell ../tools/MocList cc )
 
diff --git a/src/audiohandler.cc b/src/audiohandler.cc
new file mode 100644
index 0000000..8deb414
--- /dev/null
+++ b/src/audiohandler.cc
@@ -0,0 +1,52 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/***************************************************************************
+ *            audiohandler.cc
+ *
+ *  Fri Sep 19 19:58:05 CEST 2014
+ *  Copyright 2014 Bent Bisballe Nyeng
+ *  deva@aasimon.org
+ ****************************************************************************/
+
+/*
+ *  This file is part of SimpleRTP.
+ *
+ *  SimpleRTP is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  SimpleRTP 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 General Public License
+ *  along with SimpleRTP; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
+ */
+#include "audiohandler.h"
+
+AudioHandler::AudioHandler(QString device)
+  : ai(device.toStdString().c_str())
+{
+  start();
+}
+
+AudioHandler::~AudioHandler()
+{
+  running = false;
+  wait();
+}
+
+void AudioHandler::run()
+{
+  char pcm[4096];
+  running = true;
+
+  while(running) {
+    int sz = ai.getSamples(pcm, sizeof(pcm));
+    printf("sz: %d\n", sz);
+    framelist_t fl = oe.encode(pcm, sz);
+    emit newAudio(fl);
+  }
+}
diff --git a/src/audiohandler.h b/src/audiohandler.h
new file mode 100644
index 0000000..b61cfef
--- /dev/null
+++ b/src/audiohandler.h
@@ -0,0 +1,54 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/***************************************************************************
+ *            audiohandler.h
+ *
+ *  Fri Sep 19 19:58:05 CEST 2014
+ *  Copyright 2014 Bent Bisballe Nyeng
+ *  deva@aasimon.org
+ ****************************************************************************/
+
+/*
+ *  This file is part of SimpleRTP.
+ *
+ *  SimpleRTP is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  SimpleRTP 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 General Public License
+ *  along with SimpleRTP; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
+ */
+#ifndef __SIMPLERTP_AUDIOHANDLER_H__
+#define __SIMPLERTP_AUDIOHANDLER_H__
+
+#include <QThread>
+#include <QString>
+
+#include "audioinput.h"
+#include "opusencoder.h"
+
+class AudioHandler : public QThread {
+Q_OBJECT
+public:
+  AudioHandler(QString device);
+  ~AudioHandler();
+
+  void run();
+
+signals:
+  void newAudio(framelist_t list);
+
+private:
+  AudioInput ai;
+  OpusEncoder oe;
+
+  volatile bool running;
+};
+
+#endif/*__SIMPLERTP_AUDIOHANDLER_H__*/
diff --git a/src/audioinput.cc b/src/audioinput.cc
new file mode 100644
index 0000000..8197193
--- /dev/null
+++ b/src/audioinput.cc
@@ -0,0 +1,51 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/***************************************************************************
+ *            audioinput.cc
+ *
+ *  Fri Sep 19 19:44:11 CEST 2014
+ *  Copyright 2014 Bent Bisballe Nyeng
+ *  deva@aasimon.org
+ ****************************************************************************/
+
+/*
+ *  This file is part of SimpleRTP.
+ *
+ *  SimpleRTP is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  SimpleRTP 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 General Public License
+ *  along with SimpleRTP; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
+ */
+#include "audioinput.h"
+
+#include <stdio.h>
+
+AudioInput::AudioInput(const char *device)
+{
+  int err;
+  ai = ai_init(&err, device, "", 48000, 1);
+  printf("ai_err: %d\n", err);
+}
+
+AudioInput::~AudioInput()
+{
+  int err;
+  ai_close(&err, ai);
+  printf("ai_err: %d\n", err);
+}
+
+int AudioInput::getSamples(void *pcm, size_t size)
+{
+  int err;
+  int ret = ai_read(&err, ai, pcm, size);
+  printf("ai_err: %d\n", err);
+  return ret;
+}
diff --git a/src/audioinput.h b/src/audioinput.h
new file mode 100644
index 0000000..50e5f34
--- /dev/null
+++ b/src/audioinput.h
@@ -0,0 +1,44 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/***************************************************************************
+ *            audioinput.h
+ *
+ *  Fri Sep 19 19:44:11 CEST 2014
+ *  Copyright 2014 Bent Bisballe Nyeng
+ *  deva@aasimon.org
+ ****************************************************************************/
+
+/*
+ *  This file is part of SimpleRTP.
+ *
+ *  SimpleRTP is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  SimpleRTP 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 General Public License
+ *  along with SimpleRTP; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
+ */
+#ifndef __SIMPLERTP_AUDIOINPUT_H__
+#define __SIMPLERTP_AUDIOINPUT_H__
+
+#include <audioin.h>
+#include <stdlib.h>
+
+class AudioInput {
+public:
+  AudioInput(const char *device);
+  ~AudioInput();
+
+  int getSamples(void *pcm, size_t size);
+
+private:
+  struct ai_t *ai;
+};
+
+#endif/*__SIMPLERTP_AUDIOINPUT_H__*/
diff --git a/src/frame.cc b/src/frame.cc
new file mode 100644
index 0000000..4801897
--- /dev/null
+++ b/src/frame.cc
@@ -0,0 +1,36 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/***************************************************************************
+ *            frame.cc
+ *
+ *  Fri Sep 19 19:38:59 CEST 2014
+ *  Copyright 2014 Bent Bisballe Nyeng
+ *  deva@aasimon.org
+ ****************************************************************************/
+
+/*
+ *  This file is part of SimpleRTP.
+ *
+ *  SimpleRTP is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  SimpleRTP 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 General Public License
+ *  along with SimpleRTP; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
+ */
+#include "frame.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+
+Frame::Frame(size_t s)
+{
+  size = s;
+  data = (char*)malloc(size);
+}
diff --git a/src/frame.h b/src/frame.h
new file mode 100644
index 0000000..f5faebd
--- /dev/null
+++ b/src/frame.h
@@ -0,0 +1,45 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/***************************************************************************
+ *            frame.h
+ *
+ *  Fri Sep 19 19:38:59 CEST 2014
+ *  Copyright 2014 Bent Bisballe Nyeng
+ *  deva@aasimon.org
+ ****************************************************************************/
+
+/*
+ *  This file is part of SimpleRTP.
+ *
+ *  SimpleRTP is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  SimpleRTP 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 General Public License
+ *  along with SimpleRTP; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
+ */
+#ifndef __SIMPLERTP_FRAME_H__
+#define __SIMPLERTP_FRAME_H__
+
+#include <stdio.h>
+#include <QVector>
+
+class Frame {
+public:
+  Frame(size_t s);
+  char *data;
+  size_t size;
+};
+
+typedef QVector< Frame* > framelist_t;
+typedef unsigned int samplerate_t;
+
+//void freeFramelist(framelist_t &list);
+
+#endif/*__SIMPLERTP_FRAME_H__*/
diff --git a/src/mainwindow.cc b/src/mainwindow.cc
index e4df3f2..4dcac58 100644
--- a/src/mainwindow.cc
+++ b/src/mainwindow.cc
@@ -29,10 +29,15 @@
 #include <QLabel>
 #include <stdio.h>
 
-MainWindow::MainWindow(QString v4ldev)
-  : v4l(v4ldev)
+MainWindow::MainWindow(QString v4ldev, QString adev)
+  : v4l(v4ldev), ah(adev)
 {
-  connect(&v4l, SIGNAL(newImage(QImage)), this, SLOT(newImage(QImage)));
+  connect(&v4l, SIGNAL(newImage(QImage)),
+          this, SLOT(newImage(QImage)));
+
+  connect(&ah, SIGNAL(newAudio(framelist_t)),
+          this, SLOT(newAudio(framelist_t)));
+
   setCentralWidget(new QLabel());
 }
 
@@ -52,3 +57,8 @@ void MainWindow::newImage(QImage img)
   l->setPixmap(p);
   printf("Got one\n");
 }
+
+void MainWindow::newAudio(framelist_t list)
+{
+  printf("audio: %d frames\n", list.size());
+}
diff --git a/src/mainwindow.h b/src/mainwindow.h
index fb87dae..0ce1f4a 100644
--- a/src/mainwindow.h
+++ b/src/mainwindow.h
@@ -31,17 +31,20 @@
 #include <QString>
 
 #include "v4l.h"
+#include "audiohandler.h"
 
 class MainWindow : public QMainWindow {
 Q_OBJECT
 public:
-  MainWindow(QString v4ldev);
+  MainWindow(QString v4ldev, QString adev);
 
 public slots:
   void newImage(QImage img);
+  void newAudio(framelist_t list);
 
 private:
   V4L v4l;
+  AudioHandler ah;
 };
 
 #endif/*__SIMPLERTP_MAINWINDOW_H__*/
diff --git a/src/opusencoder.cc b/src/opusencoder.cc
new file mode 100644
index 0000000..77ea0d1
--- /dev/null
+++ b/src/opusencoder.cc
@@ -0,0 +1,133 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/***************************************************************************
+ *            opusencoder.cc
+ *
+ *  Fri Sep 19 19:21:50 CEST 2014
+ *  Copyright 2014 Bent Bisballe Nyeng
+ *  deva@aasimon.org
+ ****************************************************************************/
+
+/*
+ *  This file is part of SimpleRTP.
+ *
+ *  SimpleRTP is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  SimpleRTP 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 General Public License
+ *  along with SimpleRTP; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
+ */
+#include "opusencoder.h"
+
+#include <string.h>
+#include <opus/opus.h>
+#include <stdio.h>
+
+#include "samplecache.h"
+
+#define OPUS_BITRATE 64000
+
+struct opus_encoder_private_t {
+  OpusEncoder *ce;
+  SampleCache *cache;
+};
+
+OpusEncoder::OpusEncoder()
+{
+  prv = new struct opus_encoder_private_t;
+
+  prv->cache = new SampleCache(5760 * 10);
+
+  int error = 0;
+
+  samplerate_t srate = opus_samplerate();
+
+  prv->ce =
+    opus_encoder_create(srate, 1/*channels()*/, OPUS_APPLICATION_AUDIO, &error);
+  if(!prv->ce || error != OPUS_OK) {
+    printf("srate: %d, ch: %d, Error: %d\n", srate, 1/*channels()*/, error);
+    //throw InitException();
+  }
+
+  // 500 to 512000
+  opus_encoder_ctl(prv->ce, OPUS_SET_BITRATE(OPUS_BITRATE/*bitrate()*/));
+
+  // [0-10] with 10 representing the highest complexity.
+  opus_encoder_ctl(prv->ce, OPUS_SET_COMPLEXITY(10));
+
+  /*
+  printf("Encoder(fs: %d, ch: %d, bitrate: %d)\n", srate, channels(),
+         bitrate());
+  */
+}
+
+OpusEncoder::~OpusEncoder()
+{
+  if(prv) {
+    if(prv->ce) opus_encoder_destroy(prv->ce);
+    if(prv->cache) delete prv->cache;
+    delete prv;
+  }
+}
+
+unsigned int OpusEncoder::framesize()
+{
+  return opus_samplerate() / 1000 * OPUS_FRAME_SIZE; // 10ms audio data
+}
+
+samplerate_t OpusEncoder::opus_samplerate()
+{
+  return 48000;
+}
+
+framelist_t OpusEncoder::encode(const char *pcm, size_t size)
+{
+  framelist_t list;
+
+  //  printf("PCM size: %d\n", size);
+
+  samplerate_t srate = opus_samplerate();
+
+  if(prv->ce == NULL) {
+    //throw InitException();
+    printf("prv->ce == NULL\n");
+  }
+
+  size_t bytes_per_packet = ((OPUS_BITRATE/*bitrate()*/ *framesize())/srate+4)/8;
+
+  prv->cache->addSamples((short*)pcm, size / sizeof(short));
+
+  //size_t p = 0;
+  opus_int16 *samples = new opus_int16[framesize()];
+  while(prv->cache->cacheSize() >= framesize()) {
+    size_t sz = prv->cache->getSamples(samples, framesize());
+
+    Frame *frame = new Frame(bytes_per_packet);
+
+    int n = opus_encode(prv->ce, samples, sz / 1/*channels()*//*sizeof(short)*/,
+                        (unsigned char *)frame->data, (opus_int32)frame->size);
+
+    //printf("Compressed to %d\n", n);
+
+    if(n < 0) {
+      printf("n < 0\n");
+      //throw EncodingException();
+    }
+
+    frame->size = n;
+
+    list.push_back(frame);
+  }
+  delete[] samples;
+
+  //printf("%d frames in list\n", list.size());
+
+  return list;
+}
diff --git a/src/opusencoder.h b/src/opusencoder.h
new file mode 100644
index 0000000..b0e16fd
--- /dev/null
+++ b/src/opusencoder.h
@@ -0,0 +1,51 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/***************************************************************************
+ *            opusencoder.h
+ *
+ *  Fri Sep 19 19:21:49 CEST 2014
+ *  Copyright 2014 Bent Bisballe Nyeng
+ *  deva@aasimon.org
+ ****************************************************************************/
+
+/*
+ *  This file is part of SimpleRTP.
+ *
+ *  SimpleRTP is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  SimpleRTP 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 General Public License
+ *  along with SimpleRTP; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
+ */
+#ifndef __SIMPLERTP_OPUS_ENCODER_H__
+#define __SIMPLERTP_OPUS_ENCODER_H__
+
+#include "frame.h"
+
+// Frame size 10ms
+#define OPUS_FRAME_SIZE 10
+
+struct opus_encoder_private_t;
+
+class OpusEncoder {
+public:
+  OpusEncoder();
+  ~OpusEncoder();
+
+  framelist_t encode(const char *pcm, size_t size);
+
+  samplerate_t opus_samplerate();
+  unsigned int framesize();
+
+private:
+  struct opus_encoder_private_t *prv;
+};
+
+#endif/*__SIMPLERTP_OPUS_ENCODER_H__*/
diff --git a/src/samplecache.cc b/src/samplecache.cc
new file mode 100644
index 0000000..c9dc372
--- /dev/null
+++ b/src/samplecache.cc
@@ -0,0 +1,71 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/***************************************************************************
+ *            samplecache.cc
+ *
+ *  Fri Sep 19 19:36:13 CEST 2014
+ *  Copyright 2014 Bent Bisballe Nyeng
+ *  deva@aasimon.org
+ ****************************************************************************/
+
+/*
+ *  This file is part of SimpleRTP.
+ *
+ *  SimpleRTP is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  SimpleRTP 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 General Public License
+ *  along with SimpleRTP; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
+ */
+#include "samplecache.h"
+
+#include <stdio.h>
+
+SampleCache::SampleCache(size_t c)
+{
+  capacity = c;
+  cache = new sample_t[capacity];
+  start = 0;
+  size = 0;
+}
+
+SampleCache::~SampleCache()
+{
+  delete[] cache;
+}
+
+void SampleCache::addSamples(sample_t *samples, size_t sz)
+{
+  for(size_t i = 0; i < sz; i++) {
+    cache[(start + size) % capacity] = samples[i];
+    size++;
+  }
+}
+
+size_t SampleCache::getSamples(sample_t *samples, size_t sz)
+{
+  size_t read = 0;
+  for(size_t i = 0; i < sz; i++) {
+    if(!size) break;
+    samples[i] = cache[start % capacity];
+    read++;
+    start++;
+    size--;
+  }
+
+  start %= capacity;
+
+  return read;
+}
+
+size_t SampleCache::cacheSize()
+{
+  return size;
+}
diff --git a/src/samplecache.h b/src/samplecache.h
new file mode 100644
index 0000000..03ff756
--- /dev/null
+++ b/src/samplecache.h
@@ -0,0 +1,51 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/***************************************************************************
+ *            samplecache.h
+ *
+ *  Fri Sep 19 19:36:12 CEST 2014
+ *  Copyright 2014 Bent Bisballe Nyeng
+ *  deva@aasimon.org
+ ****************************************************************************/
+
+/*
+ *  This file is part of SimpleRTP.
+ *
+ *  SimpleRTP is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  SimpleRTP 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 General Public License
+ *  along with SimpleRTP; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
+ */
+#ifndef __SIMPLERTP_SAMPLECACHE_H__
+#define __SIMPLERTP_SAMPLECACHE_H__
+
+#include <stdlib.h>
+
+typedef short sample_t;
+
+class SampleCache {
+public:
+  SampleCache(size_t capacity);
+  ~SampleCache();
+
+  void addSamples(sample_t *samples, size_t size);
+  size_t getSamples(sample_t *samples, size_t size);
+
+  size_t cacheSize();
+
+private:
+  sample_t *cache;
+  size_t start;
+  size_t size;
+  size_t capacity;
+};
+
+#endif/*__SIMPLERTP_SAMPLECACHE_H__*/
diff --git a/src/simplertp.cc b/src/simplertp.cc
index d833cf1..837bec5 100644
--- a/src/simplertp.cc
+++ b/src/simplertp.cc
@@ -33,10 +33,12 @@ int main(int argc, char *argv[])
   QApplication app(argc, argv);
 
   QString v4ldev = "/dev/video0";
+  QString adev = "hw:2,0";
 
   if(argc > 1) v4ldev = argv[1];
+  if(argc > 2) adev = argv[2];
 
-  MainWindow wnd(v4ldev);
+  MainWindow wnd(v4ldev, adev);
   wnd.show();
 
   return app.exec();