mirror of
https://github.com/axiomatic-systems/Bento4.git
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258 lines
9.4 KiB
C++
258 lines
9.4 KiB
C++
/*****************************************************************
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| AP4 - stsc Atoms
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| Copyright 2002-2008 Axiomatic Systems, LLC
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| This file is part of Bento4/AP4 (MP4 Atom Processing Library).
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| Unless you have obtained Bento4 under a difference license,
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| this version of Bento4 is Bento4|GPL.
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| Bento4|GPL 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, or (at your option)
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| any later version.
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| Bento4|GPL 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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| You should have received a copy of the GNU General Public License
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| along with Bento4|GPL; see the file COPYING. If not, write to the
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| Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
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| 02111-1307, USA.
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****************************************************************/
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/*----------------------------------------------------------------------
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| includes
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+---------------------------------------------------------------------*/
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#include "Ap4StscAtom.h"
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#include "Ap4AtomFactory.h"
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#include "Ap4Utils.h"
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/*----------------------------------------------------------------------
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| dynamic cast support
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+---------------------------------------------------------------------*/
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AP4_DEFINE_DYNAMIC_CAST_ANCHOR(AP4_StscAtom)
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/*----------------------------------------------------------------------
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| AP4_StscAtom::Create
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+---------------------------------------------------------------------*/
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AP4_StscAtom*
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AP4_StscAtom::Create(AP4_Size size, AP4_ByteStream& stream)
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{
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AP4_UI08 version;
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AP4_UI32 flags;
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if (size < AP4_FULL_ATOM_HEADER_SIZE) return NULL;
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if (AP4_FAILED(AP4_Atom::ReadFullHeader(stream, version, flags))) return NULL;
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if (version != 0) return NULL;
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return new AP4_StscAtom(size, version, flags, stream);
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}
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/*----------------------------------------------------------------------
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| AP4_StscAtom::AP4_StscAtom
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+---------------------------------------------------------------------*/
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AP4_StscAtom::AP4_StscAtom() :
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AP4_Atom(AP4_ATOM_TYPE_STSC, AP4_FULL_ATOM_HEADER_SIZE+4, 0, 0),
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m_CachedChunkGroup(0)
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{
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}
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/*----------------------------------------------------------------------
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| AP4_StscAtom::AP4_StscAtom
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+---------------------------------------------------------------------*/
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AP4_StscAtom::AP4_StscAtom(AP4_UI32 size,
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AP4_UI08 version,
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AP4_UI32 flags,
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AP4_ByteStream& stream) :
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AP4_Atom(AP4_ATOM_TYPE_STSC, size, version, flags),
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m_CachedChunkGroup(0)
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{
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AP4_UI32 first_sample = 1;
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AP4_UI32 entry_count;
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if (size - AP4_ATOM_HEADER_SIZE < 4) return;
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stream.ReadUI32(entry_count);
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if ((size - AP4_ATOM_HEADER_SIZE - 4)/12 < entry_count) {
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return;
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}
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m_Entries.SetItemCount(entry_count);
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unsigned char* buffer = new unsigned char[entry_count*12];
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AP4_Result result = stream.Read(buffer, entry_count*12);
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if (AP4_FAILED(result)) {
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delete[] buffer;
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return;
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}
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for (unsigned int i=0; i<entry_count; i++) {
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AP4_UI32 first_chunk = AP4_BytesToUInt32BE(&buffer[i*12 ]);
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AP4_UI32 samples_per_chunk = AP4_BytesToUInt32BE(&buffer[i*12+4]);
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AP4_UI32 sample_description_index = AP4_BytesToUInt32BE(&buffer[i*12+8]);
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if (i) {
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AP4_Ordinal prev = i-1;
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m_Entries[prev].m_ChunkCount = first_chunk-m_Entries[prev].m_FirstChunk;
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first_sample += m_Entries[prev].m_ChunkCount * m_Entries[prev].m_SamplesPerChunk;
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}
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m_Entries[i].m_ChunkCount = 0; // not known yet
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m_Entries[i].m_FirstChunk = first_chunk;
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m_Entries[i].m_FirstSample = first_sample;
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m_Entries[i].m_SamplesPerChunk = samples_per_chunk;
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m_Entries[i].m_SampleDescriptionIndex = sample_description_index;
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}
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delete[] buffer;
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}
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/*----------------------------------------------------------------------
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| AP4_StscAtom::WriteFields
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+---------------------------------------------------------------------*/
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AP4_Result
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AP4_StscAtom::WriteFields(AP4_ByteStream& stream)
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{
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AP4_Result result;
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// entry count
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AP4_Cardinal entry_count = m_Entries.ItemCount();
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result = stream.WriteUI32(entry_count);
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// entries
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for (AP4_Ordinal i=0; i<entry_count; i++) {
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stream.WriteUI32(m_Entries[i].m_FirstChunk);
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if (AP4_FAILED(result)) return result;
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stream.WriteUI32(m_Entries[i].m_SamplesPerChunk);
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if (AP4_FAILED(result)) return result;
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stream.WriteUI32(m_Entries[i].m_SampleDescriptionIndex);
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if (AP4_FAILED(result)) return result;
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}
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return result;
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}
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/*----------------------------------------------------------------------
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| AP4_StscAtom::AddEntry
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+---------------------------------------------------------------------*/
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AP4_Result
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AP4_StscAtom::AddEntry(AP4_Cardinal chunk_count,
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AP4_Cardinal samples_per_chunk,
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AP4_Ordinal sample_description_index)
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{
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AP4_Ordinal first_chunk;
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AP4_Ordinal first_sample;
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AP4_Cardinal entry_count = m_Entries.ItemCount();
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if (entry_count == 0) {
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// first entry
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first_chunk = 1;
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first_sample = 1;
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} else {
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first_chunk = m_Entries[entry_count-1].m_FirstChunk+
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m_Entries[entry_count-1].m_ChunkCount;
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first_sample = m_Entries[entry_count-1].m_FirstSample+
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m_Entries[entry_count-1].m_ChunkCount*
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m_Entries[entry_count-1].m_SamplesPerChunk;
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}
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m_Entries.Append(AP4_StscTableEntry(first_chunk, first_sample, chunk_count, samples_per_chunk, sample_description_index));
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// update the atom size
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m_Size32 += 12;
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return AP4_SUCCESS;
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}
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/*----------------------------------------------------------------------
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| AP4_StscAtom::GetChunkForSample
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+---------------------------------------------------------------------*/
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AP4_Result
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AP4_StscAtom::GetChunkForSample(AP4_Ordinal sample,
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AP4_Ordinal& chunk,
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AP4_Ordinal& skip,
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AP4_Ordinal& sample_description_index)
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{
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// preconditions
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AP4_ASSERT(sample > 0);
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// decide whether to start the search from the cached index
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// or from the start
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AP4_Ordinal group;
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if (m_CachedChunkGroup < m_Entries.ItemCount() &&
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m_Entries[m_CachedChunkGroup].m_FirstSample <= sample) {
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group = m_CachedChunkGroup;
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} else {
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group = 0;
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}
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// find which group of chunk contains this one
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while (group < m_Entries.ItemCount()) {
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AP4_Cardinal sample_count =
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m_Entries[group].m_ChunkCount*m_Entries[group].m_SamplesPerChunk;
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if (sample_count == 0) {
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// unlimited samples in this group (last group)
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if (m_Entries[group].m_FirstSample > sample) {
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// something is wrong
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return AP4_ERROR_INVALID_FORMAT;
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}
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} else {
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// normal group
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if (m_Entries[group].m_FirstSample + sample_count <= sample) {
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// the sample is not in this group
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group++;
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continue;
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}
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}
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// the sample is in this group
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if (m_Entries[group].m_SamplesPerChunk == 0) {
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// something is wrong
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return AP4_ERROR_INVALID_FORMAT;
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}
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unsigned int chunk_offset =
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((sample-m_Entries[group].m_FirstSample) /
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m_Entries[group].m_SamplesPerChunk);
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chunk = m_Entries[group].m_FirstChunk + chunk_offset;
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skip = sample -
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(m_Entries[group].m_FirstSample +
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m_Entries[group].m_SamplesPerChunk*chunk_offset);
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sample_description_index = m_Entries[group].m_SampleDescriptionIndex;
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// cache the result (to accelerate finding the right group
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// next time around)
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m_CachedChunkGroup = group;
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return AP4_SUCCESS;
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}
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// chunk not found
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chunk = 0;
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skip = 0;
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sample_description_index = 0;
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return AP4_ERROR_OUT_OF_RANGE;
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}
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/*----------------------------------------------------------------------
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| AP4_StscAtom::InspectFields
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+---------------------------------------------------------------------*/
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AP4_Result
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AP4_StscAtom::InspectFields(AP4_AtomInspector& inspector)
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{
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inspector.AddField("entry_count", m_Entries.ItemCount());
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// dump table entries
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if (inspector.GetVerbosity() >= 1) {
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char header[32];
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char value[256];
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for (unsigned int i=0; i<m_Entries.ItemCount(); i++) {
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AP4_FormatString(header, sizeof(header), "entry %8d", i);
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AP4_FormatString(value, sizeof(value),
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"first_chunk=%d, first_sample=%d, chunk_count=%d, samples_per_chunk=%d, sample_desc_index=%d",
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m_Entries[i].m_FirstChunk,
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m_Entries[i].m_FirstSample,
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m_Entries[i].m_ChunkCount,
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m_Entries[i].m_SamplesPerChunk,
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m_Entries[i].m_SampleDescriptionIndex);
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inspector.AddField(header, value);
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}
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}
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return AP4_SUCCESS;
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}
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