153 lines
3.9 KiB
C++
153 lines
3.9 KiB
C++
/*
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* Copyright (C) 2017 by Jonathan Naylor G4KLX
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include "JitterBuffer.h"
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#include <cstdio>
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#include <cassert>
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CJitterBuffer::CJitterBuffer(unsigned int blockSize, unsigned int blockTime, unsigned int jitterTime, unsigned int topSequenceNumber) :
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m_blockSize(blockSize),
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m_blockTime(blockTime),
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m_topSequenceNumber(topSequenceNumber),
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m_blockCount(0U),
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m_timer(1000U, 0U, jitterTime),
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m_stopWatch(),
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m_buffer(NULL),
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m_headSequenceNumber(0U),
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m_lastData(NULL),
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m_lastDataValid(false)
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{
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assert(blockSize > 0U);
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assert(blockTime > 0U);
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assert(jitterTime > 0U);
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assert(topSequenceNumber > 0U);
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m_blockCount = jitterTime / blockTime + 1U;
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m_buffer = new JitterEntry[m_blockCount];
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for (unsigned int i = 0U; i < m_blockCount; i++)
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m_buffer[i].m_data = new unsigned char[m_blockSize];
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m_lastData = new unsigned char[m_blockSize];
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reset();
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}
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CJitterBuffer::~CJitterBuffer()
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{
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for (unsigned int i = 0U; i < m_blockCount; i++)
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delete[] m_buffer[i].m_data;
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delete[] m_buffer;
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delete[] m_lastData;
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}
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bool CJitterBuffer::addData(const unsigned char* data, unsigned int sequenceNumber)
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{
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assert(data != NULL);
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unsigned int headSequenceNumber = m_headSequenceNumber % m_topSequenceNumber;
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unsigned int tailSequenceNumber = (m_headSequenceNumber + m_blockCount) % m_topSequenceNumber;
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// Is the data out of sequence?
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if (headSequenceNumber < tailSequenceNumber) {
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if (sequenceNumber < headSequenceNumber || sequenceNumber >= tailSequenceNumber)
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return false;
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} else {
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if (sequenceNumber >= tailSequenceNumber && sequenceNumber < headSequenceNumber)
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return false;
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}
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unsigned int number;
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if (sequenceNumber >= headSequenceNumber)
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number = sequenceNumber - headSequenceNumber;
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else
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number = (sequenceNumber + m_blockCount) - headSequenceNumber;;
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unsigned int index = (m_headSequenceNumber + number) % m_blockCount;
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// Do we already have the data?
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if (m_buffer[index].m_used)
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return false;
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::memcpy(m_buffer[index].m_data, data, m_blockSize);
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m_buffer[index].m_used = true;
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if (!m_timer.isRunning())
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m_timer.start();
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return true;
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}
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JB_STATUS CJitterBuffer::getData(unsigned char* data)
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{
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assert(data != NULL);
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if (!m_timer.isRunning() || !m_timer.hasExpired()) {
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m_stopWatch.start();
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return JBS_NO_DATA;
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}
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unsigned int sequenceNumber = m_stopWatch.elapsed() / m_blockTime;
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if (m_headSequenceNumber > sequenceNumber)
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return JBS_NO_DATA;
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unsigned int head = m_headSequenceNumber % m_blockCount;
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if (m_buffer[head].m_used) {
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::memcpy(data, m_buffer[head].m_data, m_blockSize);
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m_buffer[head].m_used = false;
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// Save this data in case no more data is available next time
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::memcpy(m_lastData, m_buffer[head].m_data, m_blockSize);
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m_lastDataValid = true;
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m_headSequenceNumber++;
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return JBS_DATA;
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}
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// Return the last data frame or null data if none exists
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if (m_lastDataValid)
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::memcpy(data, m_lastData, m_blockSize);
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else
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::memset(data, 0x00U, m_blockSize);
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m_headSequenceNumber++;
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return JBS_MISSING;
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}
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void CJitterBuffer::reset()
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{
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for (unsigned int i = 0U; i < m_blockCount; i++)
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m_buffer[i].m_used = false;
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m_headSequenceNumber = 0U;
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m_lastDataValid = false;
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m_timer.stop();
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}
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void CJitterBuffer::clock(unsigned int ms)
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{
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m_timer.clock(ms);
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}
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