实时媒体流的帧率 [英] frame rate of live media streaming

问题描述

你好先生
我问现场媒体人以下问题:-
testMPEG2TransportStreamer.cpp中有什么方法可以知道帧
>正在流式传输的文件的速率???

尝试对MPEG2TransportStreamFramer进行子类化，并跟踪其
调用getNextFrame()方法.在那和gettimeofday()之间，您
应该能够计算出这个


我将其实现如下:-

Hello Sir
i asked live media people the following ques:-
Is there any way in testMPEG2TransportStreamer.cpp to know the frame
> rate of the file it is streaming????

Try subclassing MPEG2TransportStreamFramer, and keeping track when its
getNextFrame() method is called. Between that and gettimeofday(), you
should be able to calculate this


i implemented this as follows:-

// "liveMedia"
// Copyright (c) 1996-2012 Live Networks, Inc.  All rights reserved.
// Framed Sources
// Implementation

#include "FramedSource.hh"
#include <stdlib.h>
#include "GroupsockHelper.hh"
#include<math.h>

////////// FramedSource //////////
static int Framek=0;
double t1,t2,T;
float F;
struct timeval timeNow;

FramedSource::FramedSource(UsageEnvironment& env)
  : MediaSource(env),
    fAfterGettingFunc(NULL), fAfterGettingClientData(NULL),
    fOnCloseFunc(NULL), fOnCloseClientData(NULL),
    fIsCurrentlyAwaitingData(False) {
  fPresentationTime.tv_sec = fPresentationTime.tv_usec = 0; // initially
}

FramedSource::~FramedSource() {
}

Boolean FramedSource::isFramedSource() const {
  return True;
}

Boolean FramedSource::lookupByName(UsageEnvironment& env, char const* sourceName,
				   FramedSource*& resultSource) {
  resultSource = NULL; // unless we succeed

  MediaSource* source;
  if (!MediaSource::lookupByName(env, sourceName, source)) return False;

  if (!source->isFramedSource()) {
    env.setResultMsg(sourceName, " is not a framed source");
    return False;
  }

  resultSource = (FramedSource*)source;
  return True;
}

void FramedSource::getNextFrame(unsigned char* to, unsigned maxSize,
				afterGettingFunc* afterGettingFunc,
				void* afterGettingClientData,
				onCloseFunc* onCloseFunc,
				void* onCloseClientData) {

					if(Framek == 0)
					{
						gettimeofday(&timeNow, NULL);
						t1=timeNow.tv_sec+(timeNow.tv_usec/1000000.0);
						printf("value of t1 is %.6lf\t Framek %d \n",t1,Framek);
						Framek++;
					}
					else
					{
							if(Framek == 1)
							{
									gettimeofday(&timeNow, NULL);
									t2=timeNow.tv_sec+(timeNow.tv_usec/1000000.0);
									printf("value of t2 is %.6lf Framek = %d\n",t2,Framek);
									Framek++;
							}
							else
							{
								Framek =0;
								T=t2-t1;
								printf("\nFramek = %d\t t1= %.6lf\t t2= %.6lf\t T = %.6lf\t\n",Framek,t1,t2,T);
								F=(float)(1/T);
								printf("Framerate is %f\n",F);
							}
					}
  // Make sure we're not already being read:
  if (fIsCurrentlyAwaitingData) {
    envir() << "FramedSource[" << this << "]::getNextFrame(): attempting to read more than once at the same time!\n";
    envir().internalError();
  }

  fTo = to;
  fMaxSize = maxSize;
  fNumTruncatedBytes = 0; // by default; could be changed by doGetNextFrame()
  fDurationInMicroseconds = 0; // by default; could be changed by doGetNextFrame()
  fAfterGettingFunc = afterGettingFunc;
  fAfterGettingClientData = afterGettingClientData;
  fOnCloseFunc = onCloseFunc;
  fOnCloseClientData = onCloseClientData;
  fIsCurrentlyAwaitingData = True;

  doGetNextFrame();
}

void FramedSource::afterGetting(FramedSource* source) {
  source->fIsCurrentlyAwaitingData = False;
      // indicates that we can be read again
      // Note that this needs to be done here, in case the "fAfterFunc"
      // called below tries to read another frame (which it usually will)

  if (source->fAfterGettingFunc != NULL) {
    (*(source->fAfterGettingFunc))(source->fAfterGettingClientData,
				   source->fFrameSize, source->fNumTruncatedBytes,
				   source->fPresentationTime,
				   source->fDurationInMicroseconds);
  }
}

void FramedSource::handleClosure(void* clientData) {
  FramedSource* source = (FramedSource*)clientData;
  source->fIsCurrentlyAwaitingData = False; // because we got a close instead
  if (source->fOnCloseFunc != NULL) {
    (*(source->fOnCloseFunc))(source->fOnCloseClientData);
  }
}

void FramedSource::stopGettingFrames() {
  fIsCurrentlyAwaitingData = False; // indicates that we can be read again

  // Perform any specialized action now:
  doStopGettingFrames();
}

void FramedSource::doStopGettingFrames() {
  // Default implementation: Do nothing
  // Subclasses may wish to specialize this so as to ensure that a
  // subsequent reader can pick up where this one left off.
}

unsigned FramedSource::maxFrameSize() const {
  // By default, this source has no maximum frame size.
  return 0;
}

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推荐答案

邮寄给我，也许您遇到了计算问题...可能是22.17252每秒平均帧数.

您必须阅读文档...许多计算除以10000000或100000000之类的值即可得到实际的帧速率等.

Perhaps you have a calculation issue... It could be 22.17252 Frames Per Second Average.

You have to read the documentation... many of the calculations divide by things such as 10000000 or 100000000 to get the actual frame rate, etc.

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