[Live-devel] Problems with MPEG-4 streaming...

[Clark N. Taylor]

I have been attempting to stream an MPEG-4 video file using 
****./testOnDemandRTSPServer and ./openRTSP.  I have found a couple of 
problems, the first is an easy one to fix, while I need help with the 
second one.

First, when trying to stream an MPEG-4 video with a fixed frame rate, I 
found that the timing was off (it would only serve a frame every 33 
seconds, instead of 30 per second). The problem was in the 
MPEG4VideoStreamFramer.cpp file, line 388.  Even at a fixed rate,  the 
fFrameRate should be set to vop_time_increment_resolution, so the code 
now reads:

**      usingSource()->fFrameRate
    = vop_time_increment_resolution; // /(double)fixed_vop_time_increment;

I just looked at the MPEG-4 standard again, and I am pretty sure my 
implementation is correct as compared to the old implemetation.

The second problem is more puzzling.  When all I do is stream from 
testOnDemand... to openRTSP, the output file from openRTSP is not the 
same as the source file for testOnDemand....  I have looked at the 
output file, and for some reason it is sending some information at the 
beginning of the file twice.  The information sent corresponds to the 
VisualObjectSequence and VisualObjectStart headers.  Why they are 
transmitted twice is beyond me.  After the dual transmission, everything 
else seems to be okay.  Similarly, testOnDemand, when it finds the 
VisualObjectSequenceEnd  header, does not send out the last 4 bytes of 
information (the end header).

Any help in figuring out why it sends extra information is greatly 
appreciated.

Thanks,

-- 
Clark N. Taylor
PhD Student and Research Assistant
University of California, San Diego
cntaylor at ece.ucsd.edu
http://esdat.ucsd.edu/~cntaylor

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