5 Oct
2010
5 Oct
'10
10 p.m.
On Tue, Oct 05, 2010 at 02:50:10PM +0200, David Olofson wrote:
Not only that. As long as the "fragment"
initialization overhead can be kept
low, smaller fragments (within reasonable limits) can also improve throughput
as a result of smaller memory footprint.
'Fragment initialisation' should be little more than
ensuring you have the right pointers into the in/out
buffers.
Depending on the design, a synthesizer with a large
number of voices playing
can have a rather large memory footprint (intermediate buffers etc), which can
be significantly reduced by doing the processing in smaller fragments.
Obviously, this depends a lot on the design and what
hardware you're running
on, but you can be pretty certain that no modern CPU likes the occasional
short bursts of accesses scattered over a large memory area - especially not
when other application code keeps pushing your synth code and data out of the
cache between the audio callbacks.
Very true. The 'bigger' the app (voices for a synth, channels for
a mixer or daw) the more this will impact the performance. Designing
the audio code for a fairly small basic period size will pay off.
As will some simple optimisations of buffer use.
There are other possible issues, such as using FFT operations.
Calling a large FFT every N frames may have little impact on
the average load, but it could have a big one on the worst case
in a period, and in the end that's what counts.
Zyn/Yoshimi uses FFTs for some of its algorithms IIRC. Getting
the note-on timing more accurate could help to distribute those
FFT calls more evenly over Jack periods, if the input is 'human'.
Big chords generated by a sequencer or algorithmically will still
start at the same period, maybe they should be 'dispersed'...
Ciao,
--
FA
There are three of them, and Alleline.