media/formats/mp4/cenc.cc

   1 // Copyright 2014 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/formats/mp4/cenc.h"
   6
   7 #include <cstring>
   8
   9 #include "media/formats/mp4/box_reader.h"
  10 #include "media/formats/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