/** \brief Merges consecutive EbmlVoid elements into a single one
Iterates over the level 1 elements in the m_file and merges
consecutive EbmlVoid elements into a single one which covers
the same space as the smaller ones combined.
Void elements at the end of the m_file are removed as well.
*/
void
kax_analyzer_c::merge_void_elements() {
size_t start_idx = 0;
while (m_data.size() > start_idx) {
// We only have to do work on EbmlVoid elements. Skip the others.
if (!Is<EbmlVoid>(m_data[start_idx]->m_id)) {
++start_idx;
continue;
}
// Found an EbmlVoid element. See how many consecutive EbmlVoid elements
// there are at this position and calculate the combined size.
size_t end_idx = start_idx + 1;
size_t new_size = m_data[start_idx]->m_size;
while ((m_data.size() > end_idx) && Is<EbmlVoid>(m_data[end_idx]->m_id)) {
new_size += m_data[end_idx]->m_size;
++end_idx;
}
// Is this only a single EbmlVoid element? If yes continue.
if (end_idx == (start_idx + 1)) {
start_idx += 2;
continue;
}
// Write the new EbmlVoid element to the m_file.
m_file->setFilePointer(m_data[start_idx]->m_pos);
EbmlVoid evoid;
evoid.SetSize(new_size);
evoid.UpdateSize();
evoid.SetSize(new_size - evoid.HeadSize());
evoid.Render(*m_file);
// Update the internal records to reflect the changes.
m_data[start_idx]->m_size = new_size;
m_data.erase(m_data.begin() + start_idx + 1, m_data.begin() + end_idx);
start_idx += 2;
}
// See how many void elements there are at the end of the m_file.
start_idx = m_data.size();
while ((0 < start_idx) && Is<EbmlVoid>(m_data[start_idx - 1]->m_id))
--start_idx;
// If there are none then we're done.
if (m_data.size() <= start_idx)
return;
// Truncate the m_file after the last non-void element and update the m_segment size.
m_file->truncate(m_data[start_idx]->m_pos);
adjust_segment_size();
}
uint64 EbmlVoid::ReplaceWith(EbmlElement & EltToReplaceWith, IOCallback & output, bool ComeBackAfterward, bool bWithDefault)
{
EltToReplaceWith.UpdateSize(bWithDefault);
if (HeadSize() + GetSize() < EltToReplaceWith.GetSize() + EltToReplaceWith.HeadSize()) {
// the element can't be written here !
return INVALID_FILEPOS_T;
}
if (HeadSize() + GetSize() - EltToReplaceWith.GetSize() - EltToReplaceWith.HeadSize() == 1) {
// there is not enough space to put a filling element
return INVALID_FILEPOS_T;
}
uint64 CurrentPosition = output.getFilePointer();
output.setFilePointer(GetElementPosition());
EltToReplaceWith.Render(output, bWithDefault);
if (HeadSize() + GetSize() - EltToReplaceWith.GetSize() - EltToReplaceWith.HeadSize() > 1) {
// fill the rest with another void element
EbmlVoid aTmp;
aTmp.SetSize_(HeadSize() + GetSize() - EltToReplaceWith.GetSize() - EltToReplaceWith.HeadSize() - 1); // 1 is the length of the Void ID
int HeadBefore = aTmp.HeadSize();
aTmp.SetSize_(aTmp.GetSize() - CodedSizeLength(aTmp.GetSize(), aTmp.GetSizeLength(), aTmp.IsFiniteSize()));
int HeadAfter = aTmp.HeadSize();
if (HeadBefore != HeadAfter) {
aTmp.SetSizeLength(CodedSizeLength(aTmp.GetSize(), aTmp.GetSizeLength(), aTmp.IsFiniteSize()) - (HeadAfter - HeadBefore));
}
aTmp.RenderHead(output, false, bWithDefault); // the rest of the data is not rewritten
}
if (ComeBackAfterward) {
output.setFilePointer(CurrentPosition);
}
return GetSize() + HeadSize();
}
