91 lines
2.4 KiB
C++
91 lines
2.4 KiB
C++
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "media/mp4/cenc.h"
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#include <cstring>
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#include "media/base/buffer_reader.h"
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#include "media/base/buffer_writer.h"
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#include "media/mp4/rcheck.h"
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namespace {
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// According to ISO/IEC FDIS 23001-7: CENC spec, IV should be either
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// 64-bit (8-byte) or 128-bit (16-byte).
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bool IsIvSizeValid(size_t iv_size) { return iv_size == 8 || iv_size == 16; }
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// 16-bit |clear_bytes| and 32-bit |cypher_bytes|.
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const size_t kSubsampleEntrySize = sizeof(uint16) + sizeof(uint32);
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} // namespace
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namespace media {
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namespace mp4 {
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FrameCENCInfo::FrameCENCInfo() {}
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FrameCENCInfo::FrameCENCInfo(const std::vector<uint8>& iv) : iv_(iv) {}
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FrameCENCInfo::~FrameCENCInfo() {}
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bool FrameCENCInfo::Parse(uint8 iv_size, BufferReader* reader) {
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DCHECK(reader);
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// Mandated by CENC spec.
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RCHECK(IsIvSizeValid(iv_size));
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iv_.resize(iv_size);
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RCHECK(reader->ReadToVector(&iv_, iv_size));
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if (!reader->HasBytes(1))
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return true;
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uint16 subsample_count;
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RCHECK(reader->Read2(&subsample_count) &&
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reader->HasBytes(subsample_count * kSubsampleEntrySize));
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subsamples_.resize(subsample_count);
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for (uint16 i = 0; i < subsample_count; ++i) {
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uint16 clear_bytes;
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uint32 cypher_bytes;
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RCHECK(reader->Read2(&clear_bytes) &&
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reader->Read4(&cypher_bytes));
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subsamples_[i].clear_bytes = clear_bytes;
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subsamples_[i].cypher_bytes = cypher_bytes;
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}
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return true;
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}
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void FrameCENCInfo::Write(BufferWriter* writer) const {
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DCHECK(writer);
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DCHECK(IsIvSizeValid(iv_.size()));
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writer->AppendVector(iv_);
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uint16 subsample_count = subsamples_.size();
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if (subsample_count == 0)
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return;
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writer->AppendInt(subsample_count);
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for (uint16 i = 0; i < subsample_count; ++i) {
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writer->AppendInt(subsamples_[i].clear_bytes);
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writer->AppendInt(subsamples_[i].cypher_bytes);
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}
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}
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size_t FrameCENCInfo::ComputeSize() const {
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uint16 subsample_count = subsamples_.size();
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if (subsample_count == 0)
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return iv_.size();
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return iv_.size() + sizeof(subsample_count) +
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subsample_count * kSubsampleEntrySize;
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}
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size_t FrameCENCInfo::GetTotalSizeOfSubsamples() const {
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size_t size = 0;
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for (size_t i = 0; i < subsamples_.size(); ++i) {
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size += subsamples_[i].clear_bytes + subsamples_[i].cypher_bytes;
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}
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return size;
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}
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} // namespace mp4
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} // namespace media
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