demux_rtp.cpp

自己移植的linux下的流媒体播放器原代码,支持mms协议,支持ftp和http协议.

    if (demuxer->stream->eof) return 0; // source stream has closed down
  
    // Before using this packet, check to make sure that its presentation
    // time is not far behind the other stream (if any).  If it is,
    // then we discard this packet, and get another instead.  (The rest of
    // MPlayer doesn't always do a good job of synchronizing when the
    // audio and video streams get this far apart.)
    // (We don't do this when streaming over TCP, because then the audio and
    // video streams are interleaved.)
    // (Also, if the stream is *excessively* far behind, then we allow
    // the packet, because in this case it probably means that there was
    // an error in the source's timestamp synchronization.)
    const float ptsBehindThreshold = 1.0; // seconds
    const float ptsBehindLimit = 60.0; // seconds
    if (ptsBehind < ptsBehindThreshold ||
	ptsBehind > ptsBehindLimit ||
	rtspStreamOverTCP) { // packet's OK
      ds_add_packet(ds, dp);
      break;
    }
    
#ifdef DEBUG_PRINT_DISCARDED_PACKETS
    RTPState* rtpState = (RTPState*)(demuxer->priv);
    ReadBufferQueue* bufferQueue = ds == demuxer->video ? rtpState->videoBufferQueue : rtpState->audioBufferQueue;
    fprintf(stderr, "Discarding %s packet (%fs behind)\n", bufferQueue->tag(), ptsBehind);
#endif
    free_demux_packet(dp); // give back this packet, and get another one
  }

  return 1;
}

Boolean awaitRTPPacket(demuxer_t* demuxer, demux_stream_t* ds,
		       unsigned char*& packetData, unsigned& packetDataLen,
		       float& pts) {
  // Similar to "demux_rtp_fill_buffer()", except that the "demux_packet"
  // is not delivered to the "demux_stream".
  float ptsBehind;
  demux_packet_t* dp = getBuffer(demuxer, ds, True, ptsBehind); // blocking
  if (dp == NULL) return False;

  packetData = dp->buffer;
  packetDataLen = dp->len;
  pts = dp->pts;

  return True;
}

Boolean insertRTPData(demuxer_t* demuxer, demux_stream_t* ds,
		      unsigned char* data, unsigned dataLen) {
  // Begin by finding the buffer queue that we want to add data to.
  // (Get this from the RTP state, which we stored in
  //  the demuxer's 'priv' field)
  RTPState* rtpState = (RTPState*)(demuxer->priv);
  ReadBufferQueue* bufferQueue = NULL;
  if (ds == demuxer->video) {
    bufferQueue = rtpState->videoBufferQueue;
  } else if (ds == demuxer->audio) {
    bufferQueue = rtpState->audioBufferQueue;
  } else {
    fprintf(stderr, "(demux_rtp)insertRTPData: internal error: unknown stream\n");
    return False;
  }

  if (data == NULL || dataLen == 0) return False;

  demux_packet_t* dp = new_demux_packet(dataLen);
  if (dp == NULL) return False;

  // Copy our data into the buffer, and save it:
  memmove(dp->buffer, data, dataLen);
  dp->len = dataLen;
  dp->pts = 0;
  bufferQueue->savePendingBuffer(dp);
  return True;
}

static void teardownRTSPorSIPSession(RTPState* rtpState); // forward

extern "C" void demux_close_rtp(demuxer_t* demuxer) {
  // Reclaim all RTP-related state:

  // Get the RTP state that was stored in the demuxer's 'priv' field:
  RTPState* rtpState = (RTPState*)(demuxer->priv);
  if (rtpState == NULL) return;

  teardownRTSPorSIPSession(rtpState);

  UsageEnvironment* env = NULL;
  TaskScheduler* scheduler = NULL;
  if (rtpState->mediaSession != NULL) {
    env = &(rtpState->mediaSession->envir());
    scheduler = &(env->taskScheduler());
  }
  Medium::close(rtpState->mediaSession);
  Medium::close(rtpState->rtspClient);
  Medium::close(rtpState->sipClient);
  delete rtpState->audioBufferQueue;
  delete rtpState->videoBufferQueue;
  delete rtpState->sdpDescription;
  delete rtpState;

  env->reclaim(); delete scheduler;
}

////////// Extra routines that help implement the above interface functions:

#define MAX_RTP_FRAME_SIZE 50000
    // >= the largest conceivable frame composed from one or more RTP packets

static void afterReading(void* clientData, unsigned frameSize,
			 unsigned /*numTruncatedBytes*/,
			 struct timeval presentationTime,
			 unsigned /*durationInMicroseconds*/) {
  if (frameSize >= MAX_RTP_FRAME_SIZE) {
    fprintf(stderr, "Saw an input frame too large (>=%d).  Increase MAX_RTP_FRAME_SIZE in \"demux_rtp.cpp\".\n",
	    MAX_RTP_FRAME_SIZE);
  }
  ReadBufferQueue* bufferQueue = (ReadBufferQueue*)clientData;
  demuxer_t* demuxer = bufferQueue->ourDemuxer();
  RTPState* rtpState = (RTPState*)(demuxer->priv);

  if (frameSize > 0) demuxer->stream->eof = 0;

  demux_packet_t* dp = bufferQueue->dp;
  dp->len = frameSize;

  // Set the packet's presentation time stamp, depending on whether or
  // not our RTP source's timestamps have been synchronized yet: 
  Boolean hasBeenSynchronized
    = bufferQueue->rtpSource()->hasBeenSynchronizedUsingRTCP();
  if (hasBeenSynchronized) {
    if (verbose > 0 && !bufferQueue->prevPacketWasSynchronized) {
      fprintf(stderr, "%s stream has been synchronized using RTCP \n",
	      bufferQueue->tag());
    }

    struct timeval* fst = &(rtpState->firstSyncTime); // abbrev
    if (fst->tv_sec == 0 && fst->tv_usec == 0) {
      *fst = presentationTime;
    }
    
    // For the "pts" field, use the time differential from the first
    // synchronized time, rather than absolute time, in order to avoid
    // round-off errors when converting to a float:
    dp->pts = presentationTime.tv_sec - fst->tv_sec
      + (presentationTime.tv_usec - fst->tv_usec)/1000000.0;
    bufferQueue->prevPacketPTS = dp->pts;
  } else {
    if (verbose > 0 && bufferQueue->prevPacketWasSynchronized) {
      fprintf(stderr, "%s stream is no longer RTCP-synchronized \n",
	      bufferQueue->tag());
    }

    // use the previous packet's "pts" once again:
    dp->pts = bufferQueue->prevPacketPTS;
  }
  bufferQueue->prevPacketWasSynchronized = hasBeenSynchronized;

  dp->pos = demuxer->filepos;
  demuxer->filepos += frameSize;

  // Signal any pending 'doEventLoop()' call on this queue:
  bufferQueue->blockingFlag = ~0;
}

static void onSourceClosure(void* clientData) {
  ReadBufferQueue* bufferQueue = (ReadBufferQueue*)clientData;
  demuxer_t* demuxer = bufferQueue->ourDemuxer();

  demuxer->stream->eof = 1;

  // Signal any pending 'doEventLoop()' call on this queue:
  bufferQueue->blockingFlag = ~0;
}

static demux_packet_t* getBuffer(demuxer_t* demuxer, demux_stream_t* ds,
				 Boolean mustGetNewData,
				 float& ptsBehind) {
  // Begin by finding the buffer queue that we want to read from:
  // (Get this from the RTP state, which we stored in
  //  the demuxer's 'priv' field)
  RTPState* rtpState = (RTPState*)(demuxer->priv);
  ReadBufferQueue* bufferQueue = NULL;
  if (ds == demuxer->video) {
    bufferQueue = rtpState->videoBufferQueue;
  } else if (ds == demuxer->audio) {
    bufferQueue = rtpState->audioBufferQueue;
  } else {
    fprintf(stderr, "(demux_rtp)getBuffer: internal error: unknown stream\n");
    return NULL;
  }

  if (bufferQueue == NULL || bufferQueue->readSource() == NULL) {
    fprintf(stderr, "(demux_rtp)getBuffer failed: no appropriate RTP subsession has been set up\n");
    return NULL;
  }
  
  demux_packet_t* dp;
  if (!mustGetNewData) {
    // Check whether we have a previously-saved buffer that we can use:
    dp = bufferQueue->getPendingBuffer();
    if (dp != NULL) {
      ptsBehind = 0.0; // so that we always accept this data
      return dp;
    }
  }

  // Allocate a new packet buffer, and arrange to read into it:
  dp = new_demux_packet(MAX_RTP_FRAME_SIZE);
  bufferQueue->dp = dp;
  if (dp == NULL) return NULL;

  // Schedule the read operation:
  bufferQueue->blockingFlag = 0;
  bufferQueue->readSource()->getNextFrame(dp->buffer, MAX_RTP_FRAME_SIZE,
					  afterReading, bufferQueue,
					  onSourceClosure, bufferQueue);
  // Block ourselves until data becomes available:
  TaskScheduler& scheduler
    = bufferQueue->readSource()->envir().taskScheduler();
  scheduler.doEventLoop(&bufferQueue->blockingFlag);

  // Set the "ptsBehind" result parameter:
  if (bufferQueue->prevPacketPTS != 0.0
      && bufferQueue->prevPacketWasSynchronized
      && *(bufferQueue->otherQueue) != NULL
      && (*(bufferQueue->otherQueue))->prevPacketPTS != 0.0
      && (*(bufferQueue->otherQueue))->prevPacketWasSynchronized) {
    ptsBehind = (*(bufferQueue->otherQueue))->prevPacketPTS
		 - bufferQueue->prevPacketPTS;
  } else {
    ptsBehind = 0.0;
  }

  if (mustGetNewData) {
    // Save this buffer for future reads:
    bufferQueue->savePendingBuffer(dp);
  }

  return dp;
}

static void teardownRTSPorSIPSession(RTPState* rtpState) {
  MediaSession* mediaSession = rtpState->mediaSession;
  if (mediaSession == NULL) return;
  if (rtpState->rtspClient != NULL) {
    MediaSubsessionIterator iter(*mediaSession);
    MediaSubsession* subsession;

    while ((subsession = iter.next()) != NULL) {
      rtpState->rtspClient->teardownMediaSubsession(*subsession);
    }
  } else if (rtpState->sipClient != NULL) {
    rtpState->sipClient->sendBYE();
  }
}

////////// "ReadBuffer" and "ReadBufferQueue" implementation:

ReadBufferQueue::ReadBufferQueue(MediaSubsession* subsession,
				 demuxer_t* demuxer, char const* tag)
  : prevPacketWasSynchronized(False), prevPacketPTS(0.0), otherQueue(NULL),
    dp(NULL), pendingDPHead(NULL), pendingDPTail(NULL),
    fReadSource(subsession == NULL ? NULL : subsession->readSource()),
    fRTPSource(subsession == NULL ? NULL : subsession->rtpSource()),
    fOurDemuxer(demuxer), fTag(strdup(tag)) {
} 

ReadBufferQueue::~ReadBufferQueue() {
  delete fTag;

  // Free any pending buffers (that never got delivered):
  demux_packet_t* dp = pendingDPHead;
  while (dp != NULL) {
    demux_packet_t* dpNext = dp->next;
    dp->next = NULL;
    free_demux_packet(dp);
    dp = dpNext;
  }
}

void ReadBufferQueue::savePendingBuffer(demux_packet_t* dp) {
  // Keep this buffer around, until MPlayer asks for it later:
  if (pendingDPTail == NULL) {
    pendingDPHead = pendingDPTail = dp;
  } else {
    pendingDPTail->next = dp;
    pendingDPTail = dp;
  }
  dp->next = NULL;
}

demux_packet_t* ReadBufferQueue::getPendingBuffer() {
  demux_packet_t* dp = pendingDPHead;
  if (dp != NULL) {
    pendingDPHead = dp->next;
    if (pendingDPHead == NULL) pendingDPTail = NULL; 

    dp->next = NULL;
  }

  return dp;
}