On Thursday, 28 November 2013 at 10:30:36 UTC, Chris wrote:
There are voice analysis and speech processing toolkits like
Covarep and Voicebox (see links below) that were coded in
Matlab, because they were originally only prototypes. There has
been talk of porting them to C++. My first thought, as you
might imagine, was why not use D? However, I don't know if
there are any performance issues, especially for real time
systems (in speech recognition), talking about GC, or in fact
any other issues (number grinding etc.).
A lot of the analysis tools are based on some sort of HMM
(http://en.wikipedia.org/wiki/Hidden_Markov_model) and I think
D could handle that elegantly.
https://github.com/covarep/covarep
http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html
Hi, I have a little experience in dsp programming using oop
languages, so I'll try to give you my mind, but my mind is more
related to entertainment dsp softwares (asio, vst, etc...).
talking about GC
In "pseudo" real time (RT) audio (one or many buffer are
overlapped) you are a in a loop (interesting example is
bufferswitch in asio). It's time critical and performance
critical, so you'll never create a class neither allocate a
buffer here...The idea is: what does trigger the GC: memory
allocation and dynamic class instance creation. It's like in GUI
programming: you don't destroy and recreate many objects in the
"resize/realign" message handler...So the GC problem is solved:
there is no GC problem because in RT dsp you won't do something
stupid that'll trig a GC pass.
In speech recognition you'll mostly use some frequency-domain
technics (not to name the fft), so basically if you don't want to
trigger a GC pass, don't use build-in array and make your own
array using alloc/malloc/free. For the classes it's the same, you
can still make your own class allocator/deallocator, like
specified in the manual (even if they say it's deprecated). With
user managed classes and array you'll avoid most of the GC
passes...But it doesn't mean that the most important stuff is:
not to allocate in the audio buffer loop.
