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(const uint8_t* data,
+                         uint8_t length,
+                         FrameMarks* frame_marks) {
+  RTC_DCHECK(frame_marks);
+  RTC_DCHECK(length);
+  // Set frame marking data
+  frame_marks->startOfFrame = (data[0] & 0x80) != 0;
+  frame_marks->endOfFrame = (data[0] & 0x40) != 0;
+  frame_marks->independent = (data[0] & 0x20) != 0;
+  frame_marks->discardable = (data[0] & 0x10) != 0;
+
+  // Check variable length
+  if (length==1) {

[danilchap, 2017/06/28 16:07:06]

please use git cl format (to add spaces around '==')

[sergio.garcia.murillo, 2017/06/29 12:58:58]

Done.

+    // We are non-scalable
+    frame_marks->baseLayerSync = 0;
+    frame_marks->temporalLayerId = 0;
+    frame_marks->spatialLayerId = 0;
+    frame_marks->tl0PicIdx = 0;
+  } else if (length==3) {
+    // Set scalable parts
+    frame_marks->baseLayerSync = (data[0] & 0x08) != 0;
+    frame_marks->temporalLayerId = (data[0] & 0x07) != 0;

[danilchap, 2017/06/28 16:07:06]

remove "!= 0"

[sergio.garcia.murillo, 2017/06/29 12:58:57]

msvc gives C4800 warning: forcing value to bool 'true' or 'false' (performance
warning) if not

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

is temporal_layer_id a boolean field?

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

uuuupsss!

+    frame_marks->spatialLayerId = data[1];
+    frame_marks->tl0PicIdx = 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.baseLayerSync
+      || (frame_marks.temporalLayerId
+            && frame_marks.temporalLayerId != kNoTemporalIdx)
+      || (frame_marks.spatialLayerId
+            && frame_marks.spatialLayerId != kNoSpatialIdx)
+      || (frame_marks.tl0PicIdx
+            && frame_marks.tl0PicIdx != (uint8_t)kNoTl0PicIdx)

[danilchap, 2017/06/28 16:07:06]

use static_cast instead of c-cast, 

[sergio.garcia.murillo, 2017/06/29 12:58:58]

Done.

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

still c-cast in this line

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

Done. This time for sure.

+  )
+    return 3;
+  else
+    return 1;
+}
+
+bool FrameMarking::Write(uint8_t* data, const FrameMarks& frame_marks) {
+  data[0] = frame_marks.startOfFrame ? 0x80 : 0x00;
+  data[0] |= frame_marks.endOfFrame ? 0x40 : 0x00;
+  data[0] |= frame_marks.independent ? 0x20 : 0x00;
+  data[0] |= frame_marks.discardable ? 0x10 : 0x00;
+
+  // Check if it is scalable
+  if (frame_marks.baseLayerSync
+       || (frame_marks.temporalLayerId

[danilchap, 2017/06/28 16:07:06]

is temporal_layer_id == 0 a value that shouldn't be put into extension?

[sergio.garcia.murillo, 2017/06/29 12:58:57]

No, but if temporal and spatial layer are 0 and tl0_pic_idx, then header
extension is shorter and the last 2 bytes are omitted.:

+            && frame_marks.temporalLayerId != kNoTemporalIdx)
+       || (frame_marks.spatialLayerId
+            && frame_marks.spatialLayerId != kNoSpatialIdx)
+       || (frame_marks.tl0PicIdx
+            && frame_marks.tl0PicIdx != (uint8_t)kNoTl0PicIdx)
+    ) {
+    data[0] |= frame_marks.baseLayerSync ? 0x08 : 0x00;
+    data[0] |= (frame_marks.temporalLayerId & 0x07);
+    data[1] = frame_marks.spatialLayerId;
+    data[2] = frame_marks.tl0PicIdx;
+  }
+  return true;
+}
+
 }  // namespace webrtc