Add Support for Audio MIME Types

The EME spec technically requires CDMs to treat audio/mp4 and
video/mp4 equivalently, as well as audio/webm and video/webm. We had
only been accepting video/mp4 and video/webm up until now.

This change also centralizes handling of init data types in the shared
CDM code instead of having it spread across multiple places in the
codebase.

(This is a merge of https://widevine-internal-review.googlesource.com/9532/
from the Widevine CDM repo.)

Bug: 13564917
Change-Id: Ib8bdfb2b003ffb00e8f0559561335abb3c5778b0

libwvdrmengine/cdm/core/src/initialization_data.cpp

@@ -0,0 +1,121 @@
+// Copyright 2014 Google Inc. All Rights Reserved.
+
+#include "initialization_data.h"
+
+#include "buffer_reader.h"
+#include "log.h"
+#include "properties.h"
+#include "wv_cdm_constants.h"
+
+namespace wvcdm {
+
+InitializationData::InitializationData(const std::string& type,
+                                       const CdmInitData& data)
+    : type_(type), is_cenc_(false), is_webm_(false) {
+  if (type == ISO_BMFF_VIDEO_MIME_TYPE || type == ISO_BMFF_AUDIO_MIME_TYPE) {
+    is_cenc_ = true;
+  } else if (type == WEBM_VIDEO_MIME_TYPE || type == WEBM_AUDIO_MIME_TYPE) {
+    is_webm_ = true;
+  }
+
+  if (is_supported()) {
+    if (Properties::extract_pssh_data() && is_cenc()) {
+      ExtractWidevinePssh(data, &data_);
+    } else {
+      data_ = data;
+    }
+  }
+}
+
+// Parse a blob of multiple concatenated PSSH atoms to extract the first
+// Widevine PSSH.
+// TODO(kqyang): temporary workaround - remove after b/7928472 is resolved
+bool InitializationData::ExtractWidevinePssh(
+    const CdmInitData& init_data, CdmInitData* output) {
+
+  BufferReader reader(
+      reinterpret_cast<const uint8_t*>(init_data.data()), init_data.length());
+
+  // TODO(kqyang): Extracted from an actual init_data;
+  // Need to find out where it comes from.
+  static const uint8_t kWidevineSystemId[] = {
+      0xED, 0xEF, 0x8B, 0xA9, 0x79, 0xD6, 0x4A, 0xCE,
+      0xA3, 0xC8, 0x27, 0xDC, 0xD5, 0x1D, 0x21, 0xED,
+  };
+
+  // one PSSH blob consists of:
+  // 4 byte size of the PSSH atom, inclusive
+  // "pssh"
+  // 4 byte flags, value 0
+  // 16 byte system id
+  // 4 byte size of PSSH data, exclusive
+  while (1) {
+    // size of PSSH atom, used for skipping
+    uint32_t size;
+    if (!reader.Read4(&size)) {
+      LOGW("CdmEngine::ExtractWidevinePssh: Unable to read PSSH atom size");
+      return false;
+    }
+
+    // "pssh"
+    std::vector<uint8_t> pssh;
+    if (!reader.ReadVec(&pssh, 4)) {
+      LOGW("CdmEngine::ExtractWidevinePssh: Unable to read PSSH literal");
+      return false;
+    }
+    if (memcmp(&pssh[0], "pssh", 4)) {
+      LOGW("CdmEngine::ExtractWidevinePssh: PSSH literal not present");
+      return false;
+    }
+
+    // flags
+    uint32_t flags;
+    if (!reader.Read4(&flags)) {
+      LOGW("CdmEngine::ExtractWidevinePssh: Unable to read PSSH flags");
+      return false;
+    }
+    if (flags != 0) {
+      LOGW("CdmEngine::ExtractWidevinePssh: PSSH flags not zero");
+      return false;
+    }
+
+    // system id
+    std::vector<uint8_t> system_id;
+    if (!reader.ReadVec(&system_id, sizeof(kWidevineSystemId))) {
+      LOGW("CdmEngine::ExtractWidevinePssh: Unable to read system ID");
+      return false;
+    }
+
+    if (memcmp(&system_id[0], kWidevineSystemId,
+               sizeof(kWidevineSystemId))) {
+      // skip the remaining contents of the atom,
+      // after size field, atom name, flags and system id
+      if (!reader.SkipBytes(
+          size - 4 - 4 - 4 - sizeof(kWidevineSystemId))) {
+        LOGW("CdmEngine::ExtractWidevinePssh: Unable to rest of PSSH atom");
+        return false;
+      }
+      continue;
+    }
+
+    // size of PSSH box
+    uint32_t pssh_length;
+    if (!reader.Read4(&pssh_length)) {
+      LOGW("CdmEngine::ExtractWidevinePssh: Unable to read PSSH box size");
+      return false;
+    }
+
+    output->clear();
+    if (!reader.ReadString(output, pssh_length)) {
+      LOGW("CdmEngine::ExtractWidevinePssh: Unable to read PSSH");
+      return false;
+    }
+
+    return true;
+  }
+
+  // we did not find a matching record
+  return false;
+}
+
+}  // namespace wvcdm