Implement FrameMarking header extension support

webrtc/modules/rtp_rtcp/source/rtp_header_extensions.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.
  */
 
@@ skipping 295 matching lines @@
 }
 
 size_t RepairedRtpStreamId::ValueSize(const std::string& rsid) {
   return RtpStreamId::ValueSize(rsid);
 }
 
 bool RepairedRtpStreamId::Write(uint8_t* data, const std::string& rsid) {
   return RtpStreamId::Write(data, rsid);
 }
 
+// For Frame Marking RTP Header Extension:
+//
+// https://tools.ietf.org/html/draft-ietf-avtext-framemarking-04#page-4
+// This extensions provides meta-information about the RTP streams outside the
+// encrypted media payload, an RTP switch can do codec-agnostic
+// selective forwarding without decrypting the payload.
+//
+// for Non-Scalable Streams:
+//
+//     0                   1
+//     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+//    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//    |  ID=? |  L=0  |S|E|I|D|0 0 0 0|
+//    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//
+// for Scalable Streams:
+//
+//     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
+//    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//    |  ID=? |  L=2  |S|E|I|D|B| TID |   LID         |    TL0PICIDX  |
+//    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//
+constexpr RTPExtensionType FrameMarking::kId;
+constexpr const char* FrameMarking::kUri;
+
+bool FrameMarking::Parse(rtc::ArrayView<const uint8_t> data,
+                         FrameMarks* frame_marks) {
+  RTC_DCHECK(frame_marks);
+
+  if (data.empty())
+    return false;
+
+  // Set frame marking data
+  frame_marks->start_of_frame = (data[0] & 0x80) != 0;
+  frame_marks->end_of_frame = (data[0] & 0x40) != 0;
+  frame_marks->independent = (data[0] & 0x20) != 0;
+  frame_marks->discardable = (data[0] & 0x10) != 0;
+
+  // Check variable length.
+  if (data.size() == 1) {
+    // We are non-scalable.
+    frame_marks->base_layer_sync = 0;

[danilchap, 2017/06/29 13:47:26]

may be = false

[sergio.garcia.murillo, 2017/06/30 10:09:23]

Done.

+    frame_marks->temporal_layer_id = 0;
+    frame_marks->spatial_layer_id = 0;
+    frame_marks->tl0_pic_idx = 0;
+  } else if (data.size() == 3) {
+    // Set scalable parts
+    frame_marks->base_layer_sync = (data[0] & 0x08) != 0;
+    frame_marks->temporal_layer_id = (data[0] & 0x07) != 0;
+    frame_marks->spatial_layer_id = data[1];
+    frame_marks->tl0_pic_idx = data[2];
+  } else {
+    // Incorrect length.
+    return false;
+  }
+  return true;
+}
+
+size_t FrameMarking::ValueSize(const FrameMarks& frame_marks) {
+  // Check if it is scalable.
+  if (frame_marks.base_layer_sync ||
+      (frame_marks.temporal_layer_id &&
+       frame_marks.temporal_layer_id != kNoTemporalIdx) ||
+      (frame_marks.spatial_layer_id &&
+       frame_marks.spatial_layer_id != kNoSpatialIdx) ||
+      (frame_marks.tl0_pic_idx &&
+       frame_marks.tl0_pic_idx != (uint8_t)kNoTl0PicIdx))
+    return 3;
+  else
+    return 1;
+}
+
+bool FrameMarking::Write(uint8_t* data, const FrameMarks& frame_marks) {
+  data[0] = frame_marks.start_of_frame ? 0x80 : 0x00;
+  data[0] |= frame_marks.end_of_frame ? 0x40 : 0x00;
+  data[0] |= frame_marks.independent ? 0x20 : 0x00;
+  data[0] |= frame_marks.discardable ? 0x10 : 0x00;
+
+  // Check if it is scalable.
+  if (frame_marks.base_layer_sync ||
+      (frame_marks.temporal_layer_id &&
+       frame_marks.temporal_layer_id != kNoTemporalIdx) ||
+      (frame_marks.spatial_layer_id &&
+       frame_marks.spatial_layer_id != kNoSpatialIdx) ||
+      (frame_marks.tl0_pic_idx &&
+       frame_marks.tl0_pic_idx != static_cast<uint8_t>(kNoTl0PicIdx))) {
+    data[0] |= frame_marks.base_layer_sync ? 0x08 : 0x00;
+    data[0] |= (frame_marks.temporal_layer_id & 0x07);
+    data[1] = frame_marks.spatial_layer_id;
+    data[2] = frame_marks.tl0_pic_idx;
+  }
+  return true;
+}
+
 }  // namespace webrtc