chromecast/media/cdm/chromecast_init_data.cc

   1 // Copyright 2015 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 "chromecast/media/cdm/chromecast_init_data.h"
   6
   7 #include "base/logging.h"
   8 #include "base/stl_util.h"
   9 #include "media/base/bit_reader.h"
  10 #include "media/cdm/cenc_utils.h"
  11
  12 namespace chromecast {
  13 namespace media {
  14
  15 #define RCHECK(x)   \
  16   do {              \
  17     if (!(x))       \
  18       return false; \
  19   } while (0)
  20
  21 namespace {
  22
  23 const uint8_t kChromecastPlayreadyUuid[] = {
  24     0x2b, 0xf8, 0x66, 0x80, 0xc6, 0xe5, 0x4e, 0x24,
  25     0xbe, 0x23, 0x0f, 0x81, 0x5a, 0x60, 0x6e, 0xb2};
  26
  27 }  // namespace
  28
  29 ChromecastInitData::ChromecastInitData() {
  30 }
  31
  32 ChromecastInitData::~ChromecastInitData() {
  33 }
  34
  35 bool FindChromecastInitData(const std::vector<uint8_t>& init_data,
  36                             InitDataMessageType type,
  37                             ChromecastInitData* chromecast_init_data_out) {
  38   // Chromecast initData assumes a CENC data format and searches for PSSH boxes
  39   // with SystemID |kChromecastPlayreadyUuid|. The PSSH box content is as
  40   // follows:
  41   // * |type| (2 bytes, InitDataMessageType)
  42   // * |data| (all remaining bytes)
  43   // Data may or may not be present and is specific to the given |type|.
  44
  45   std::vector<uint8_t> pssh_data;
  46   if (!::media::GetPsshData(
  47           init_data, std::vector<uint8_t>(kChromecastPlayreadyUuid,
  48                                           kChromecastPlayreadyUuid +
  49                                               sizeof(kChromecastPlayreadyUuid)),
  50           &pssh_data)) {
  51     return false;
  52   }
  53
  54   ::media::BitReader reader(vector_as_array(&pssh_data), pssh_data.size());
  55
  56   uint16_t msg_type;
  57   RCHECK(reader.ReadBits(2 * 8, &msg_type));
  58   RCHECK(msg_type < static_cast<uint16_t>(InitDataMessageType::END));
  59   RCHECK(msg_type == static_cast<uint16_t>(type));
  60
  61   chromecast_init_data_out->type = static_cast<InitDataMessageType>(msg_type);
  62   chromecast_init_data_out->data.assign(
  63       pssh_data.begin() + reader.bits_read() / 8, pssh_data.end());
  64   return true;
  65 }
  66
  67 }  // namespace media
  68 }  // namespace chromecast