    AP4_SampleLocator() : 
        m_TrakIndex(0), 
        m_SampleTable(NULL), 
        m_SampleIndex(0), 
        m_ChunkIndex(0) {}
    AP4_SampleLocator() : 
        m_TrakIndex(0), 
        m_SampleTable(NULL), 
        m_SampleIndex(0), 
        m_ChunkIndex(0) {}