[Live-devel] Live555 Streaming from a live source

[Ross Finlayson]

>We are trying to stream from a live source with Live555.
>We implement our own DeviceSource class. In this class we implement 
>doGetNextFrame in the following (logic) way. We remove all the 
>unnecessary implementation details so you can see the idea
>
>If no frame is available do the following
>
>   nextTask() = 
>envir().taskScheduler().scheduleDelayedTask(30000,(TaskFunc*)nextTime, 
>this);
>If a frame is available do the following
>
>If (fFrameSize < fMaxSize)

This should be "<=", not "<".

Also, I hope you are setting "fFrameSize" properly before you get to 
this "if" statement.

>{
>memcpy(fTo, Buffer_getUserPtr(hEncBuf) ,fFrameSize); // copy the 
>frame to Live555
>nextTask() = 
>envir().taskScheduler().scheduleDelayedTask(0,(TaskFunc*)FramedSource::afterGetting, 
>this);

You can probably replace this last statement with:
	FramedSource::afterGetting(this);
which is more efficient (and will avoid infinite recursion, because 
you're reading from a live source).

>}
>else
>{
>What should we do? (We do not understand what should we do in this option)

Something like this:
	fNumTruncatedBytes = fFrameSize - fMaxSize;
	fFrameSize = fMaxSize;
	FramedSource::afterGetting(this);

Note, however, that if data gets truncated, then it is *dropped*. 
This means that you should make sure that your downstream object 
always has enough buffer space to avoid trunction - i.e., so that 
fMaxSize is always >= fFrameSize
-- 

Ross Finlayson
Live Networks, Inc.
http://www.live555.com/