[speex-dev] speed and memory
marc at wimba.com
Mon Nov 3 02:02:25 PST 2003
I've never had any OutOfMEmoryExceptions in my tests, and I think
I've been rather thourough, although probably much more thourought
testing narrowband than wideband. Having said this, it is very hard to
get memory leaks in java, so I am sceptical about that. That memory
might not be used optimally is more likely the case. More often then not
reducing memory use increases processor use. Although is you feel like
doing some profiling of the code and find where the problem is, I wouild
be glad to improve things.
As far as processor is concerned. Speex is not the hungriest of
codecs out ther, but it is a CELP codec and therefore more advanced and
processor intensive then older codecs such as GSM or ADPCM. It's doing
quite a bit of signal processing. The code in Java is running in a
virtual machine so it's not going to perform as well as native C. I
haven't done too many test on dual processor machines, but on singal
processor machines 350 MHz really pretty close to the minimum
requirement for real time encoding. You had better not have anything
else running on your computer at the same time though. There are several
things that reduce the resources required. Narrowband uses less than
wideband or UWB. Lower quality uses less resources than higher quality.
Finally there is also an encoder setting called complexity.Reducing that
also reduces the required resources. Also the Use of VBR could slightly
increase the processor usage, and stereo too (if both stereo channels
are identical, best to reduce it to mono and encode mono rather than
encode stereo). But the best thing to do is play around with the various
settings and see which settings suit you best with the given resources
on your hardware.
Head of research
Ulrich B. Staudinger wrote:
> i switched to use the encoder.processData() and
> encoder.getProcessedData() of jspeex. however it looks to me like a
> memory leak ... memory usage is increasing very fast and there is no
> visible stop ... after about five minutes java.lang.OutOfMemory
> occurs. I think it must be the jspeex component, because before i
> added jspeex to my app usage was constant at about 5mb.
> is it possible to be jspeex ?
> another issue is speed - when doing UWB, quality 3, 44100 stereo
> encoding my cpu load goes up to 100% on a dual 350MHz - is it correct
> that lower quality uses significantly less cpu resources?
> thanks in advance,
> p.s. the quality for that bandwidth is really awesome ! Must be cool
> wavelets and other stuff or something alike ... ! Wow!
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