Ignore Camera and Flip bits in CVO when parsing video rotation

webrtc/common_types.h

 /*
  *  Copyright (c) 2012 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 767 matching lines @@
   // Audio Level includes both level in dBov and voiced/unvoiced bit. See:
   // https://datatracker.ietf.org/doc/draft-lennox-avt-rtp-audio-level-exthdr/
   bool hasAudioLevel;
   bool voiceActivity;
   uint8_t audioLevel;
 
   // For Coordination of Video Orientation. See
   // http://www.etsi.org/deliver/etsi_ts/126100_126199/126114/12.07.00_60/
   // ts_126114v120700p.pdf
   bool hasVideoRotation;
+  // This byte actually represents the whole CVO byte: |0 0 0 0 C F R R|.

[danilchap, 2016/08/25 15:54:17]

Another way to fix this bug 
is to change rtp_utility.cc line 400:
header->extension.videoRotation = ptr[0] & 0x03;
then this byte would be rotation only.
(VideoOrientation::Parse is still unused)

[magjed_webrtc, 2016/08/26 07:56:26]

Right. I'm not sure if we should parse the rotation and C/F bits directly in
rtp_utility.cc or not. This seemed like the easiest solution, then I don't need
to remove or change the name of ConvertCVOByteToVideoRotation. We mix the names
"videoRotation", "videoOrientation", and CVO interchangeably in the code, so
it's a bit confusing.

[pthatcher1, 2016/08/29 18:52:59]

I think it makes most sense for videoRotation here to be an enum, like we have
videoRotation in other places.  If it's not an enum, then it should be named
something that makes it clear it is a CVObyte, perhaps calling it |cvo|.  But
giving it a name that sounds like an enum and value that's a cvo-specific byte
is confusing.  

[magjed_webrtc, 2016/08/31 11:06:59]

To be clear, this mixup is not something I added in this CL. It has been like
that since CVO was added here: https://webrtc-codereview.appspot.com/42439004.
Actually, reading the review discussion in that CL, it was you that pushed for
changing the name of this byte from coordinationOfVideoOrientation to
videoRotation.

In the latest patch set, I discard the camera and flip bits of the CVO byte in
order to make videoRotation an enum. It will be future work for someone to parse
and store the camera and flip bits in rtp_utility.cc and
rtp_header_extensions.cc.

   uint8_t videoRotation;
 
   PlayoutDelay playout_delay = {-1, -1};
 };
 
 struct RTPHeader {
   RTPHeader();
 
   bool markerBit;
   uint8_t payloadType;
@@ skipping 111 matching lines @@
 enum class RtcpMode { kOff, kCompound, kReducedSize };
 
 enum NetworkState {
   kNetworkUp,
   kNetworkDown,
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_COMMON_TYPES_H_