Hi all, I encountered a problem needs your help.
I have developped a H.264 video decoder on DVEVM6446 board. It runns
on DSP side and I use the codec egine mechansim to control this decoder
from ARM side.
For performance evaluation, i count the time consumed by this decoder
both from ARM side and DSP side.
On DSP side, I use the cycle hardware register to statistic the
processing time for each frame. e.g.:
H264VIDEODEC_process( )
{
.....
start = cycle();
video_dec_one_frame(); //main function for decoding one
frame
end = cycle();
decDspTime = diffcycle(start, end);
....
}
On ARM side, I use the gettimeofday() function to statistic the
processing time for each frame.
.....
start = gettimeofday();
VIDDEC_process();
end = gettimeofday();
encDspTime = difftime(start, end);
.....
It seems that in most cases, the statistical time on ARM side is close
to the statistical time on DSP side, commonly, the former is about 1ms
larger than the latter for a CIF decoder.
But in some occasional cases, the statistical time on ARM side is very
very larger than the time on DSP side. e.g., for some frames, the former
is 16ms, the latter is 9ms!!!! It is unacceptable for my real-time
requirement!
What is the cause for this case? which module take up the additional
time, i.e.: (16ms - 9ms) ?
As i know, there is a communication process between DSP and ARM when
ARM receives VIDDEC_process() function call. Is this part takes too much
time? and why and why is it so large? How can i decrease it?
Any response is appreiated!
BR,
ZhouXiao
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