build_notes_chromium.md

Build notes for Chromium

Chromium supports three types of CDMs:

• Internal from source (Clear Key, which is implemented internally by aes_decryptor.cc)
• Pepper-based CDMs (used for desktop and Chrome OS)
• Platform-based (e.g. Android using MediaDrm APIs)

Source: David Dorwin, Feb 2014

Pepper Plugin API (PPAPI) integration notes

Tested with version: MAJOR=37 MINOR=0 BUILD= 2041 PATCH=6

Configuration

Make sure to have the following gyp variables set before building. Easiest way is to place a ~/.gyp/include.gypi with contents:

{
  'variables': {
    'ffmpeg_branding': 'Chrome',
    'proprietary_codecs': 1,
    'enable_pepper_cdms': 1
  }
}

Code hooks

To make the CDM available in the chromium build the key system needs to be registered in the file $CHROMIUM_ROOT/src/chrome/renderer/media/chrome_key_systems.cc

Similar as for the function AddExternalClearKey the new key system needs to be registered by adding and calling the following function:

// External Open CDM.
static void AddExternalOpenCdm(
    std::vector<KeySystemInfo>* concrete_key_systems) {
  static const char kExternalOpenCdmKeySystem[] =
      "com.opencdm.mockdrm";
  static const char kExternalOpenCdmPepperType[] =
      "application/x-ppapi-open-cdm";

  std::vector<base::string16> additional_param_names;
  std::vector<base::string16> additional_param_values;
  if (!IsPepperCdmAvailable(kExternalOpenCdmPepperType,
                             &additional_param_names,
                             &additional_param_values)) {
    return;
  }

  KeySystemInfo info(kExternalOpenCdmKeySystem);

#if defined(USE_PROPRIETARY_CODECS)
  info.supported_codecs |= content::EME_CODEC_MP4_ALL;
#endif  // defined(USE_PROPRIETARY_CODECS)

  info.pepper_type = kExternalOpenCdmPepperType;

  concrete_key_systems->push_back(info);
}

Finally, add the following call into the AddChromeKeySystems function subsequent the check if Pepper CDMs are enabled:

if defined(ENABLE_PEPPER_CDMS)
  AddExternalClearKey(key_systems_info);
  AddExternalOpenCdm(key_systems_info);