Support HLS MPEG2 TS with SAMPLE-AES encryption.

media/formats/mp2t/ts_section_cat.cc

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "media/formats/mp2t/ts_section_cat.h"
+
+#include <vector>
+
+#include "base/logging.h"
+#include "media/base/bit_reader.h"
+#include "media/formats/mp2t/descriptors.h"
+#include "media/formats/mp2t/mp2t_common.h"
+
+namespace media {
+namespace mp2t {
+
+TsSectionCat::TsSectionCat(const RegisterCencPidsCb& register_cenc_ids_cb)
+    : register_cenc_ids_cb_(register_cenc_ids_cb), version_number_(-1) {}
+
+TsSectionCat::~TsSectionCat() {}
+
+bool TsSectionCat::ParsePsiSection(BitReader* bit_reader) {
+  DCHECK(bit_reader);
+  // Read the fixed section length.
+  int table_id;
+  int section_syntax_indicator;
+  int dummy_zero;
+  int reserved;
+  int section_length;
+  int version_number;
+  int current_next_indicator;
+  int section_number;
+  int last_section_number;
+  RCHECK(bit_reader->ReadBits(8, &table_id));
+  RCHECK(bit_reader->ReadBits(1, &section_syntax_indicator));
+  RCHECK(bit_reader->ReadBits(1, &dummy_zero));
+  RCHECK(bit_reader->ReadBits(2, &reserved));
+  RCHECK(bit_reader->ReadBits(12, &section_length));
+  RCHECK(section_length >= 5);
+  RCHECK(section_length <= 1021);
+  RCHECK(bit_reader->ReadBits(18, &reserved));
+  RCHECK(bit_reader->ReadBits(5, &version_number));
+  RCHECK(bit_reader->ReadBits(1, &current_next_indicator));
+  RCHECK(bit_reader->ReadBits(8, &section_number));
+  RCHECK(bit_reader->ReadBits(8, &last_section_number));
+  section_length -= 5;
+
+  // Perform a few more verifications, including:
+  // - Table ID should be 1 for a CAT.
+  // - section_syntax_indicator should be one.
+  RCHECK(table_id == 0x1);
+  RCHECK(section_syntax_indicator);
+  RCHECK(!dummy_zero);
+
+  Descriptors descriptors;
+  int ca_pid, pssh_pid;
+  RCHECK(descriptors.Read(bit_reader, section_length - 4));
+  RCHECK(descriptors.HasCADescriptorCenc(&ca_pid, &pssh_pid));
+  int crc32;
+  RCHECK(bit_reader->ReadBits(32, &crc32));
+
+  // Just ignore the CAT if not applicable yet.
+  if (!current_next_indicator) {
+    DVLOG(1) << "Not supported: received a CAT not applicable yet";
+    return true;
+  }
+
+  // Ignore the CAT if it hasn't changed.
+  if (version_number == version_number_)
+    return true;
+
+  // Can now register the PIDs.
+  register_cenc_ids_cb_.Run(ca_pid, pssh_pid);
+
+  version_number_ = version_number;
+
+  return true;
+}
+
+void TsSectionCat::ResetPsiSection() {
+  version_number_ = -1;
+}
+
+}  // namespace mp2t
+}  // namespace media