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/**********
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.,
59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
**********/
// "liveMedia"
// Copyright (c) 1996-2005 Live Networks, Inc. All rights reserved.
// RTP sink for AC3 audio
// Implementation
#include "AC3AudioRTPSink.hh"
AC3AudioRTPSink::AC3AudioRTPSink(UsageEnvironment& env, Groupsock* RTPgs,
u_int8_t rtpPayloadFormat,
u_int32_t rtpTimestampFrequency)
: AudioRTPSink(env, RTPgs, rtpPayloadFormat,
rtpTimestampFrequency, "AC3") {
}
AC3AudioRTPSink::~AC3AudioRTPSink() {
}
AC3AudioRTPSink*
AC3AudioRTPSink::createNew(UsageEnvironment& env, Groupsock* RTPgs,
u_int8_t rtpPayloadFormat,
u_int32_t rtpTimestampFrequency) {
return new AC3AudioRTPSink(env, RTPgs,
rtpPayloadFormat, rtpTimestampFrequency);
}
Boolean AC3AudioRTPSink
::frameCanAppearAfterPacketStart(unsigned char const* /*frameStart*/,
unsigned /*numBytesInFrame*/) const {
// (For now) allow at most 1 frame in a single packet:
return False;
}
void AC3AudioRTPSink
::doSpecialFrameHandling(unsigned fragmentationOffset,
unsigned char* frameStart,
unsigned numBytesInFrame,
struct timeval frameTimestamp,
unsigned numRemainingBytes) {
// Update the "NDU" header.
// Also set the "Data Unit Header" for the frame, because we
// have already allotted space for this, by virtue of the fact that
// (for now) we pack only one frame in each RTP packet:
unsigned char headers[2];
headers[0] = numFramesUsedSoFar() + 1;
Boolean isFragment = numRemainingBytes > 0 || fragmentationOffset > 0;
unsigned const totalFrameSize
= fragmentationOffset + numBytesInFrame + numRemainingBytes;
unsigned const fiveEighthsPoint = totalFrameSize/2 + totalFrameSize/8;
Boolean haveFiveEighths
= fragmentationOffset == 0 && numBytesInFrame >= fiveEighthsPoint;
headers[1] = (isFragment<<5)|(haveFiveEighths<<4); // F|B
// Note: TYP==0, RDT==0 ???, T==0 ???
setSpecialHeaderBytes(headers, sizeof headers);
if (numRemainingBytes == 0) {
// This packet contains the last (or only) fragment of the frame.
// Set the RTP 'M' ('marker') bit:
setMarkerBit();
}
// Important: Also call our base class's doSpecialFrameHandling(),
// to set the packet's timestamp:
MultiFramedRTPSink::doSpecialFrameHandling(fragmentationOffset,
frameStart, numBytesInFrame,
frameTimestamp,
numRemainingBytes);
}
unsigned AC3AudioRTPSink::specialHeaderSize() const {
// There's a 1 byte "NDU" header.
// There's also a 1-byte "Data Unit Header" preceding each frame in
// the RTP packet, but since we (for now) pack only one frame in
// each RTP packet, we also count this here:
return 1 + 1;
}
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