Index: media/formats/mp2t/ts_section_cets_ecm.cc |
diff --git a/media/formats/mp2t/ts_section_cets_ecm.cc b/media/formats/mp2t/ts_section_cets_ecm.cc |
new file mode 100644 |
index 0000000000000000000000000000000000000000..1679c0307181cbc319e56ac9a407458b0327abae |
--- /dev/null |
+++ b/media/formats/mp2t/ts_section_cets_ecm.cc |
@@ -0,0 +1,84 @@ |
+// 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_cets_ecm.h" |
+ |
+#include "base/logging.h" |
+#include "media/base/bit_reader.h" |
+#include "media/base/decrypt_config.h" |
+#include "media/formats/mp2t/mp2t_common.h" |
+ |
+namespace media { |
+namespace mp2t { |
+ |
+TsSectionCetsEcm::TsSectionCetsEcm( |
+ const RegisterDecryptConfigCb& register_decrypt_config_cb) |
+ : register_decrypt_config_cb_(register_decrypt_config_cb) {} |
+ |
+TsSectionCetsEcm::~TsSectionCetsEcm() {} |
+ |
+bool TsSectionCetsEcm::Parse(bool payload_unit_start_indicator, |
+ const uint8_t* buf, |
+ int size) { |
+ DCHECK(buf); |
+ BitReader bit_reader(buf, size); |
+ int num_states; |
+ bool next_key_id_flag; |
+ bool no_byte_align; |
+ int iv_size; |
+ std::string key_id; |
+ int transport_scrambling_control; |
+ int num_au; |
+ bool key_id_flag; |
+ int au_byte_offset_size; |
+ std::string iv; |
+ std::vector<SubsampleEntry> subsamples_empty; |
+ // TODO(dougsteed). Currently we allow only a subset of the possible values. |
+ // When we flesh out this implementation to cover all of ISO/IEC 23001-9 we |
+ // will need to generalize this. |
+ RCHECK(bit_reader.ReadBits(2, &num_states)); |
+ RCHECK(num_states == 1); |
+ RCHECK(bit_reader.ReadFlag(&next_key_id_flag) && !next_key_id_flag); |
+ // TODO(dougsteed). The standard (ISO/IEC 23001-9:2014) reserves 3 bits, |
+ // whereas it likely was intended to be 5 bits to follow the usual practice of |
+ // syncing to a byte boundary for the byte oriented fields that follow. |
+ // For now, we plan to use it with byte alignment for convenience. Rather than |
+ // just having an unadvertized deviation from the standard, I have repurposed |
+ // the first reserved bit as a flag. This approach gives flexibility for the |
+ // future if the standard is fixed or comes into wide use in its present form. |
+ RCHECK(bit_reader.ReadFlag(&no_byte_align)); |
+ if (no_byte_align) |
+ RCHECK(bit_reader.SkipBits(2)); |
+ else |
+ RCHECK(bit_reader.SkipBits(4)); |
+ RCHECK(bit_reader.ReadBits(8, &iv_size)); |
+ RCHECK(iv_size == 16); |
+ RCHECK(bit_reader.ReadString(128, &key_id)); |
+ RCHECK(bit_reader.ReadBits(2, &transport_scrambling_control)); |
+ RCHECK(transport_scrambling_control == 0); |
+ RCHECK(bit_reader.ReadBits(6, &num_au)); |
+ RCHECK(num_au == 1); |
+ RCHECK(bit_reader.ReadFlag(&key_id_flag) && !key_id_flag); |
+ RCHECK(bit_reader.SkipBits(3)); |
+ RCHECK(bit_reader.ReadBits(4, &au_byte_offset_size)); |
+ RCHECK(au_byte_offset_size == 0); |
+ RCHECK(bit_reader.ReadString(128, &iv)); |
+ // The CETS-ECM is supposed to use adaptation field stuffing to fill the TS |
+ // packet, so there should be no data left to read. |
+ RCHECK(bit_reader.bits_available() == 0); |
+ DecryptConfig decrypt_config(key_id, iv, subsamples_empty); |
+ register_decrypt_config_cb_.Run(decrypt_config); |
+ return true; |
+} |
+ |
+void TsSectionCetsEcm::Flush() { |
+ // No pending state. |
+} |
+ |
+void TsSectionCetsEcm::Reset() { |
+ // No state to clean up. |
+} |
+ |
+} // namespace mp2t |
+} // namespace media |