1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include "media/mp4/cenc.h" 6 7 #include <cstring> 8 9 #include "media/mp4/box_reader.h" 10 #include "media/mp4/rcheck.h" 11 12 namespace media { 13 namespace mp4 { 14 15 FrameCENCInfo::FrameCENCInfo() {} 16 FrameCENCInfo::~FrameCENCInfo() {} 17 18 bool FrameCENCInfo::Parse(int iv_size, BufferReader* reader) { 19 const int kEntrySize = 6; 20 // Mandated by CENC spec 21 RCHECK(iv_size == 8 || iv_size == 16); 22 23 memset(iv, 0, sizeof(iv)); 24 for (int i = 0; i < iv_size; i++) 25 RCHECK(reader->Read1(&iv[i])); 26 27 if (!reader->HasBytes(1)) return true; 28 29 uint16 subsample_count; 30 RCHECK(reader->Read2(&subsample_count) && 31 reader->HasBytes(subsample_count * kEntrySize)); 32 33 subsamples.resize(subsample_count); 34 for (int i = 0; i < subsample_count; i++) { 35 uint16 clear_bytes; 36 uint32 cypher_bytes; 37 RCHECK(reader->Read2(&clear_bytes) && 38 reader->Read4(&cypher_bytes)); 39 subsamples[i].clear_bytes = clear_bytes; 40 subsamples[i].cypher_bytes = cypher_bytes; 41 } 42 return true; 43 } 44 45 bool FrameCENCInfo::GetTotalSizeOfSubsamples(size_t* total_size) const { 46 size_t size = 0; 47 for (size_t i = 0; i < subsamples.size(); i++) { 48 size += subsamples[i].clear_bytes; 49 RCHECK(size >= subsamples[i].clear_bytes); // overflow 50 size += subsamples[i].cypher_bytes; 51 RCHECK(size >= subsamples[i].cypher_bytes); // overflow 52 } 53 *total_size = size; 54 return true; 55 } 56 57 } // namespace mp4 58 } // namespace media 59
