[rtp_rtcp] rtcp::Sli packet moved into own file and got Parse function

webrtc/modules/rtp_rtcp/source/rtcp_packet/sli.cc

+/*
+ *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "webrtc/modules/rtp_rtcp/source/rtcp_packet/sli.h"
+
+#include "webrtc/base/checks.h"
+#include "webrtc/base/logging.h"
+#include "webrtc/modules/rtp_rtcp/source/byte_io.h"
+
+using webrtc::RTCPUtility::RtcpCommonHeader;
+
+namespace webrtc {
+namespace rtcp {
+const uint8_t Sli::kFeedbackMessageType;
+
+// RFC 4585: Feedback format.
+//
+// Common packet format:
+//
+//   0                   1                   2                   3
+//   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//  |V=2|P|   FMT   |       PT      |          length               |
+//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//  |                  SSRC of packet sender                        |
+//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//  |                  SSRC of media source                         |
+//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//  :            Feedback Control Information (FCI)                 :
+//  :                                                               :
+//
+// Slice loss indication (SLI) (RFC 4585).
+// FCI:
+//   0                   1                   2                   3
+//   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//  |            First        |        Number           | PictureID |
+//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+Sli::Macroblocks::Macroblocks(uint8_t picture_id,
+                              uint16_t first,
+                              uint16_t count) {

[åsapersson, 2016/01/11 12:13:54]

call count -> number?

[danilchap, 2016/01/11 15:36:32]

Done.

+  RTC_DCHECK_LE(first, 0x1fff);
+  RTC_DCHECK_LE(count, 0x1fff);
+  RTC_DCHECK_LE(picture_id, 0x3d);

[åsapersson, 2016/01/11 12:13:54]

3d -> 3f?

[danilchap, 2016/01/11 15:36:32]

Done.

+  item_ = (first << 19) | (count << 6) | picture_id;
+}
+void Sli::Macroblocks::Parse(const uint8_t* buffer) {
+  item_ = ByteReader<uint32_t>::ReadBigEndian(buffer);
+}
+void Sli::Macroblocks::Create(uint8_t* buffer) const {
+  ByteWriter<uint32_t>::WriteBigEndian(buffer, item_);
+}
+
+bool Sli::Parse(const RtcpCommonHeader& header, const uint8_t* payload) {
+  RTC_DCHECK_EQ(header.packet_type, kPacketType);
+  RTC_DCHECK_EQ(header.count_or_format, kFeedbackMessageType);
+
+  if (header.payload_size_bytes <
+      kCommonFeedbackLength + Macroblocks::kLength) {
+    LOG(LS_WARNING) << "Packet is too small to be a valid SLI packet";
+    return false;
+  }
+
+  size_t macroblocks_number =

[åsapersson, 2016/01/11 12:13:54]

maybe items?

[danilchap, 2016/01/11 15:36:32]

Done.

[åsapersson, 2016/01/12 12:35:26]

maybe just items or num_items, number_of_items

[danilchap, 2016/01/12 12:56:35]

Done. number_of_items is obviously more clear name.  

+      (header.payload_size_bytes - kCommonFeedbackLength) /
+      Macroblocks::kLength;
+
+  ParseCommonFeedback(payload);
+  macroblocks_.resize(macroblocks_number);
+
+  const uint8_t* next_fci_field = payload + kCommonFeedbackLength;
+  for (Macroblocks& block : macroblocks_) {
+    block.Parse(next_fci_field);
+    next_fci_field += Macroblocks::kLength;
+  }
+
+  return true;
+}
+
+bool Sli::Create(uint8_t* packet,
+                 size_t* index,
+                 size_t max_length,
+                 RtcpPacket::PacketReadyCallback* callback) const {
+  RTC_DCHECK(!macroblocks_.empty());

[åsapersson, 2016/01/11 12:13:54]

use RTC_CHECK here?

[danilchap, 2016/01/11 15:36:32]

Done, but isn't it better to send invalid sli packet than to crash?

[åsapersson, 2016/01/12 12:35:26]

Ok, RTC_DCHECK might be better.

[danilchap, 2016/01/12 12:56:35]

Reverted.

+  while (*index + BlockLength() > max_length) {
+    if (!OnBufferFull(packet, index, callback))
+      return false;
+  }
+  CreateHeader(kFeedbackMessageType, kPacketType, HeaderLength(), packet,
+               index);
+  CreateCommonFeedback(packet + *index);
+  *index += kCommonFeedbackLength;
+  for (const Macroblocks& mb : macroblocks_) {
+    mb.Create(packet + *index);
+    *index += Macroblocks::kLength;
+  }
+  return true;
+}
+
+}  // namespace rtcp
+}  // namespace webrtc