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>> Why are you delaying the call to "FramedSource::afterGetting(this)" by 50 ms?
>
>
> But why not?
Because it’s putting the delay in the wrong place - i.e., after the data has
been delivered to the downstream object, but before a RTP packet has been sent.
In other words, you’re unnecessarily delaying the sending of the first (and
subsequent) RTP packets.
If you want to introduce a delay between sending RTP packets, then the right
way to do this is to set the “fDurationInMicroseconds” member variable when you
deliver the frame data. This will cause the RTP packet to get sent
immediately, but will delay the subsequent call to “doGetNextFrame()” (to
request the next frame of data).
> If, e.g., my source has a 1fps frame rate, why not wait 900ms avoid a
> busy-wait?
If your source has a 1 fps frame rate, then you *may* set
“fDurationInMicroseconds” to 1000000 (i.e., 1 million) each time you deliver a
frame’s data (i.e., each time you copy data to the pointer pointed to by
“fTo”). *Then*, you notify the downstream object that the frame delivery has
been done, by calling
FramedSource::afterGetting(this);
i.e., without any delay.
However, because you are streaming from a ‘live’ source, you don’t really need
to set “fDurationInMicroseconds” at all (in which case it will be left at its
default value of 0). But your use of the term “busy-wait” suggests that you
are thinking about this code wrong - i.e., you think that you need to
periodically ‘poll’ your encoder for data. This is wrong. LIVE555-based
applications are event driven. The right way to get data from an external
encoder is to make the arrival of data an asynchronous ‘event’ - either by
reading from a socket (if the encoder is an open file or pipe), or by
encapsulating your encoder in a separate thread that calls “triggerEvent()”
(the only LIVE555 function that can be called from an external thread) when new
encoded data becomes available. I suggest that you read
“liveMedia/DeviceSource.cpp” once again - noting in particular the comments in
that file.
Ross Finlayson
Live Networks, Inc.
http://www.live555.com/
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