Beginnings of a generic jitter buffer for all modes.

JitterBuffer.cpp

@@ -0,0 +1,127 @@
+/*
+*   Copyright (C) 2017 by Jonathan Naylor G4KLX
+*
+*   This program 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.
+*
+*   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 General Public License
+*   along with this program; if not, write to the Free Software
+*   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+#include "JitterBuffer.h"
+
+#include <cstdio>
+#include <cassert>
+
+CJitterBuffer::CJitterBuffer(unsigned int blockSize, unsigned int blockTime, unsigned int jitterTime, unsigned int topSequenceNumber) :
+m_blockSize(blockSize),
+m_blockTime(blockTime),
+m_topSequenceNumber(topSequenceNumber),
+m_blockCount(0U),
+m_timer(1000U, 0U, jitterTime),
+m_stopWatch(),
+m_buffer(NULL),
+m_headSequenceNumber(0U)
+{
+	assert(blockSize > 0U);
+	assert(blockTime > 0U);
+	assert(jitterTime > 0U);
+	assert(topSequenceNumber > 0U);
+
+	m_blockCount = jitterTime / blockTime + 1U;
+	
+	m_buffer = new JitterEntry[m_blockCount];
+
+	for (unsigned int i = 0U; i < m_blockCount; i++)
+		m_buffer[i].m_data = new unsigned char[m_blockSize];
+
+	reset();
+}
+
+CJitterBuffer::~CJitterBuffer()
+{
+	for (unsigned int i = 0U; i < m_blockCount; i++)
+		delete[] m_buffer[i].m_data;
+
+	delete[] m_buffer;
+}
+
+bool CJitterBuffer::addData(const unsigned char* data, unsigned int sequenceNumber)
+{
+	assert(data != NULL);
+
+	unsigned int headSequenceNumber =  m_headSequenceNumber % m_topSequenceNumber;
+	unsigned int tailSequenceNumber = (m_headSequenceNumber + m_blockCount) % m_topSequenceNumber;
+	
+	// Is the data out of sequence?
+	if (headSequenceNumber < tailSequenceNumber) {
+		if (sequenceNumber < headSequenceNumber || sequenceNumber >= tailSequenceNumber)
+			return false;
+	} else {
+		if (sequenceNumber >= tailSequenceNumber && sequenceNumber < headSequenceNumber)
+			return false;
+	}
+
+	unsigned int number = sequenceNumber - headSequenceNumber;
+
+	// Do we already have the data?
+	if (m_buffer[number].m_used)
+		return false;
+
+	::memcpy(m_buffer[number].m_data, data, m_blockSize);
+	m_buffer[number].m_used = true;
+
+	if (!m_timer.isRunning())
+		m_timer.start();
+	
+	return true;
+}
+
+JB_STATUS CJitterBuffer::getData(unsigned char* data)
+{
+	assert(data != NULL);
+
+	if (!m_timer.isRunning() || !m_timer.hasExpired()) {
+		m_stopWatch.start();
+		return JBS_NO_DATA;
+	}
+
+	unsigned int sequenceNumber = m_stopWatch.elapsed() / m_blockTime;
+	if (m_headSequenceNumber > sequenceNumber)
+		return JBS_NO_DATA;
+	
+	if (m_buffer[m_headSequenceNumber].m_used) {
+		::memcpy(data, m_buffer[m_headSequenceNumber].m_data, m_blockSize);
+
+		m_headSequenceNumber++;
+
+		return JBS_DATA;
+	}
+	
+	m_headSequenceNumber++;
+	
+	return JBS_REPEAT;
+}
+
+void CJitterBuffer::reset()
+{
+	for (unsigned int i = 0U; i < m_blockCount; i++)
+		m_buffer[i].m_used = false;
+
+	m_headSequenceNumber = 0U;
+	
+	m_timer.stop();
+}
+
+void CJitterBuffer::clock(unsigned int ms)
+{
+	m_timer.clock(ms);
+}