[Live-devel] [ Propose ] Fix multi-thread issue when RTCPInstance new OutPacketBuffer

[JW Liao]

*Environment*

   1. Create multiple RTSP server in one process and every server is
   different thread ( multi-thread ).
   2. Create 100 session to play video from the multiple RTSP server at the
   same time, so every server will be handle some sessions.

*Warning Message :*

   - MultiFramedRTPSink::afterGettingFrame1(): The input frame data was too
   large for our buffer size (2884).  1731 bytes of trailing data was dropped!
    Correct this by increasing "OutPacketBuffer::maxSize" to at least 3181,
   *before* creating this 'RTPSink'.  (Current value is 1450.)
   - MultiFramedRTPSink::afterGettingFrame1(): The input frame data was too
   large for our buffer size (2884).  9449 bytes of trailing data was dropped!
    Correct this by increasing "OutPacketBuffer::maxSize" to at least 10899,
   *before* creating this 'RTPSink'.  (Current value is 1450.)
   - MultiFramedRTPSink::afterGettingFrame1(): The input frame data was too
   large for our buffer size (2884).  350 bytes of trailing data was dropped!
    Correct this by increasing "OutPacketBuffer::maxSize" to at least 1800,
   *before* creating this 'RTPSink'.  (Current value is 1450.)
   - MultiFramedRTPSink::afterGettingFrame1(): The input frame data was too
   large for our buffer size (2884).  926 bytes of trailing data was dropped!
    Correct this by increasing "OutPacketBuffer::maxSize" to at least 2376,
   *before* creating this 'RTPSink'.  (Current value is 1450.)

*Root Cause :*

   - *OutPacketBuffer::maxSize* type is *static*, when multi-thread
   running, the value will be modified at class *RTCPInstance* constructor,
   show source code below:

  // A hack to save buffer space, because RTCP packets are always small:

  unsigned savedMaxSize = OutPacketBuffer::maxSize;

  *OutPacketBuffer::maxSize* = maxRTCPPacketSize;

   fOutBuf = new OutPacketBuffer(preferredPacketSize, maxRTCPPacketSize);

  OutPacketBuffer::maxSize = savedMaxSize;

  if (fOutBuf == NULL) return;

*Analysis :*

   - *RTCPInstance* constructor modify *OutPacketBuffer::maxSize* just want
   to help class *OutPacketBuffer* constructor compute *maxNumPackets*,
   show source below :

*MediaSink.cpp*


OutPacketBuffer::OutPacketBuffer(unsigned preferredPacketSize,unsigned
maxPacketSize)

  : fPreferred(preferredPacketSize), fMax(maxPacketSize),

    fOverflowDataSize(0) {

  unsigned *maxNumPackets* = (*maxSize* + (maxPacketSize-1))/maxPacketSize;

  fLimit = maxNumPackets*maxPacketSize;

  fBuf = new unsigned char[fLimit];

  resetPacketStart();

  resetOffset();

  resetOverflowData();

}

*Resolve :*

   - Add new constructor for OutPacketBuffer and pre-compute
   the maxNumPackets value then pass it.

*RTCP.cpp*

#if 0

  // A hack to save buffer space, because RTCP packets are always small:

  unsigned savedMaxSize = OutPacketBuffer::maxSize;

  OutPacketBuffer::maxSize = maxRTCPPacketSize;

  fOutBuf = new OutPacketBuffer(preferredPacketSize, maxRTCPPacketSize);

  OutPacketBuffer::maxSize = savedMaxSize;

  if (fOutBuf == NULL) return;

#else

  *unsigned maxNumPackets = (maxRTCPPacketSize +
(maxRTCPPacketSize-1))/maxRTCPPacketSize;*

  fOutBuf = new OutPacketBuffer(preferredPacketSize, maxRTCPPacketSize,
*maxNumPackets*);

  if (fOutBuf == NULL) return;

#endif


*MediaSink.cpp*

OutPacketBuffer::OutPacketBuffer(unsigned preferredPacketSize,unsigned
maxPacketSize, *unsigned maxNumPackets*)

  : fPreferred(preferredPacketSize), fMax(maxPacketSize),

    fOverflowDataSize(0) {

  fLimit = maxNumPackets*maxPacketSize;

  fBuf = new unsigned char[fLimit];

  resetPacketStart();

  resetOffset();

  resetOverflowData();

}


BR
ChunWei
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