live555/liveMedia/VP8VideoRTPSource.cpp

/**********
This library is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by the
Free Software Foundation; either version 2.1 of the License, or (at your
option) any later version. (See <http://www.gnu.org/copyleft/lesser.html>.)

This library is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for
more details.

You should have received a copy of the GNU Lesser General Public License
along with this library; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA
**********/
// "liveMedia"
// Copyright (c) 1996-2015 Live Networks, Inc.  All rights reserved.
// VP8 Video RTP Sources
// Implementation

#include "VP8VideoRTPSource.hh"

VP8VideoRTPSource*
VP8VideoRTPSource::createNew(UsageEnvironment& env, Groupsock* RTPgs,
			      unsigned char rtpPayloadFormat,
			      unsigned rtpTimestampFrequency) {
  return new VP8VideoRTPSource(env, RTPgs, rtpPayloadFormat,
			       rtpTimestampFrequency);
}

VP8VideoRTPSource
::VP8VideoRTPSource(UsageEnvironment& env, Groupsock* RTPgs,
		     unsigned char rtpPayloadFormat,
		     unsigned rtpTimestampFrequency)
  : MultiFramedRTPSource(env, RTPgs, rtpPayloadFormat, rtpTimestampFrequency) {
}

VP8VideoRTPSource::~VP8VideoRTPSource() {
}

#define incrHeader do { ++resultSpecialHeaderSize; ++headerStart; if (--packetSize == 0) return False; } while (0)

Boolean VP8VideoRTPSource
::processSpecialHeader(BufferedPacket* packet,
                       unsigned& resultSpecialHeaderSize) {
  unsigned char* headerStart = packet->data();
  unsigned packetSize = packet->dataSize();

  // The special header is from 1 to 6 bytes long.
  if (packetSize == 0) return False; // error
  resultSpecialHeaderSize = 1; // unless we learn otherwise

  u_int8_t const byte1 = *headerStart;
  Boolean const X = (byte1&0x80) != 0;
  Boolean const S = (byte1&0x10) != 0;
  u_int8_t const PartID = byte1&0x0F;

  fCurrentPacketBeginsFrame = S && PartID == 0;
  fCurrentPacketCompletesFrame = packet->rtpMarkerBit(); // RTP header's "M" bit

  if (X) {
    incrHeader;

    u_int8_t const byte2 = *headerStart;
    Boolean const I = (byte2&0x80) != 0;
    Boolean const L = (byte2&0x40) != 0;
    Boolean const T = (byte2&0x20) != 0;
    Boolean const K = (byte2&0x10) != 0;

    if (I) {
      incrHeader;
      if ((*headerStart)&0x80) { // extension flag in the PictureID is set
	incrHeader;
      }
    }

    if (L) incrHeader;
    if (T||K) incrHeader;
  }
  
  return True;
}

char const* VP8VideoRTPSource::MIMEtype() const {
  return "video/VP8";
}