Thanks, I'll also try this:
http://sourceforge.net/p/fluidsynth/wiki/BuildingWithCMake/ Brad
On Sat, Jan 2, 2016, at 10:36 AM, Element Green wrote:
>
> Element Green
> ---------- Forwarded message ---------- From: "element1green"
> <element1gr...@gmail.com> Date: Jan 2, 2016 11:33 AM Subject: Re: [fluid-
> dev] question on linear interpolation To: "FluidSynth mailing list"
> <fluid-dev@nongnu.org>
> Cc:
>
> Use capital -O0 for the optimization.
> Element
> On Jan 2, 2016 10:58 AM, "Brad Stewart" <brads...@fastmail.us> wrote:
>>> Yes, I am building the shell. Interestingly, it stores
the executable in a hidden directory
<workspace>/fluidsynth/src/.libs
>>>
>>>
The console window only displays the shell and I see no error
messages. I'll need to figure out how to display internal
printf messages.
>>>
>>>
I am having problems building a debug variant. I tried adding -g
-o0 but get many build errors. This might be due to the way
Eclipse sets up autotools. Any quick hints?
>>>
>>>
--Brad
>>>
>>>
>>>
>> On 01/02/2016 08:08 AM, Element Green
wrote:
>>> Hello Brad,
>>>
>>> It sounds like you really need to get debugging working.
From what you said about the "interp num" command, I assume
you are building the fluidsynth command shell. Do you get any
relevant error messages on the console (probably the same
terminal you are running fluidsynth from - but may be hidden
if you are accessing the shell through TCP for example). Make
sure you are able to see console messages, since there may be
some useful error messages getting output.
>>>
>>> When running the interp command it should
call fluid_synth_set_interp_method(). I would get debugging
working and set a breakpoint on that function and make sure it
is doing all the calls to fluid_channel_set_interp_method()
for every channel.
>>>
>>> Best regards,
>>>
>>> Element
>>>
>>> On Sat, Jan 2, 2016 at 4:57 AM, Marcus
Weseloh <mar...@weseloh.cc> wrote:
>>>> Hi Brad,
>>>>
>>>>
Out of curiosity I checked that the interp setting
actually had an
>>>>
effect by adding printf statements to the relevant
functions. The
>>>>
fluid_rvoice_dsp_interpolate_linear function is called
just fine if
>>>>
you set "interp 1" in the FluidSynth shell. Seems like
you've got a
>>>>
problem with your devel setup...
>>>>
>>>>
Cheers,
>>>>
>>>>
Marcus
>>>>
>>>>
2016-01-02 0:33 GMT+01:00 Brad Stewart
<brads...@fastmail.us>:
>>>>
> So I recompiled the code and added a return at the
beginning of the function
>>>>
> fluid_rvoice_dsp_interpolate_linear
(fluid_rvoice_dsp_t *voice).
>>>>
>
>>>>
> I also tried adding a for(;;) and a printf.
>>>>
>
>>>>
> I tried several interp num commands (with num from
to 7) but it seems it
>>>>
> never gets to this function. All audio sounds as
it should.
>>>>
>
>>>>
> Could you comment please?
>>>>
>
>>>>
> Thanks,
>>>>
> Brad
>>>>
>
>>>>
> P.S.I imported the project into Eclipse Mars
using import "existing tools
>>>>
> as Autotools project". It compiled with some
warnings. It seems to run OK.
>>>>
> But I was unable to build a debug version of it so
I could use gdb to trace
>>>>
> through the code.
>>>>
>
>>>>
>
>>>>
>
>>>>
>
>>>>
>
>>>>
> On 12/31/2015 03:36 PM, Brad Stewart wrote:
>>>>
>
>>>>
> Could you confirm that "interp 1" command line
invokes the Linear
>>>>
> Interpolation function?
>>>>
> Thanks,
>>>>
> Brad
>>>>
>
>>>>
>
>>>>
>
>>>>
> On Thu, Dec 31, 2015, at 01:36 PM, Element Green
wrote:
>>>>
>
>>>>
> Hello Brad,
>>>>
>
>>>>
> To my knowledge the audio sample data is used as is
in FluidSynth. The
>>>>
> sample rate of the data and the current pitch of a
voice determine how it
>>>>
> gets interpolated. So I believe your analysis is
correct, that
>>>>
> interpolating between two identical values will
yield that value with the
>>>>
> linear interpolation algorithm, regardless of where
in between the two
>>>>
> points the new interpolated point lies. The higher
order interpolation
>>>>
> algorithms will be affected by additional sample
points though, so it would
>>>>
> not be true in those cases unless additional
consecutive points had the same
>>>>
> value (for the number of points used by the
interpolation algorithm).
>>>>
>
>>>>
> At this point I'm not sure what you are asking
anymore though.
>>>>
>
>>>>
> Best regards,
>>>>
>
>>>>
> Element
>>>>
>
>>>>
>
>>>>
> On Thu, Dec 31, 2015 at 12:38 PM, Brad Stewart <brads...@fastmail.us>
wrote:
>>>>
>
>>>>
>
>>>>
> Hi Mr Green,
>>>>
>
>>>>
> Yes, I am carrying the fractional part. In my
case, it's 12 bits and I
>>>>
> shift right by 4 to get the upper 8 bits to index
to the coefficient table.
>>>>
>
>>>>
> But let me cite an example,
>>>>
> Suppose I have x[i]=100 and x[i+1]=100 (which
occurs often in a lower note
>>>>
> frequency).
>>>>
>
>>>>
> Assume after looking up the coefficient table, you
get coeffs[0] = .3 and
>>>>
> coeffs[1] = .7
>>>>
> So if you do the math,
>>>>
> out=100*.3 + 100*.7 = 100. So no change.
>>>>
> In my case, I can have 4 consecutive values of 100
(at note = 60) as shown
>>>>
> in the previous images.
>>>>
>
>>>>
> So any of the coefficients in the table will return
a value and 1-value, if
>>>>
> the current sample and then next are the same, the
output is always the
>>>>
> original value. So in the general case where
sampe[i]=sample[i+1],
>>>>
>
>>>>
> out = sample* frac + sample*(1-frac) = sample*(frac
+1 -frac) = sample =
>>>>
> out.
>>>>
>
>>>>
> This is why I was asking if you're adding to the
data set by up-sampling,
>>>>
> pre-filtering, or something else. This is hinted
at in the paper by Olli
>>>>
> Niemitalo.
>>>>
> I suppose you that the interpolated value could be
stuffed back into the
>>>>
> original data (recursion) but I don't see that
occurring in
>>>>
> fluid_voice_dsp.c.
>>>>
>
>>>>
> Brad
>>>>
>
>>>>
>
>>>>
>
>>>>
>
>>>>
> On Wed, Dec 30, 2015, at 07:21 PM, Element Green
wrote:
>>>>
>
>>>>
> Hello Brad,
>>>>
>
>>>>
>
>>>>
> On Wed, Dec 30, 2015 at 7:42 PM, Brad Stewart <brads...@fastmail.us>
wrote:
>>>>
>
>>>>
> Hi,
>>>>
>
>>>>
> I'm developing an embedded project using some of
the code in FluidSynth.
>>>>
>
>>>>
> The target is an ARM Cortex M4 and am using integer
math. Most of the
>>>>
> coefficients are in Q15 format.
>>>>
>
>>>>
> So far, I'm able to generate different notes with
sound font files and use
>>>>
> some of the CMSIS DSP libraries to generate high
order IIR filters.
>>>>
>
>>>>
> But I am having no luck with any interpolation
routines. I ran some tests
>>>>
> using the command line version of FluidSynth on a
laptop running Ubuntu 14.
>>>>
>
>>>>
> I created a sine wave sound font (using Swami) with
a sample rate of 20050
>>>>
> Hz, root note is 86. It's looping over several
cycles. The image
>>>>
> Midi_60_no_interpolation.jpg picture shows the
result with no interpolation
>>>>
> (I get the exact same results on my embedded
platform). This is using
>>>>
> "interp 0". (Note that the ringing is due to the
sinc function in the Codec
>>>>
> filter/decimator.)
>>>>
>
>>>>
> If I then set "interp 1", I get the image as shown
in
>>>>
> Midi_60_linear_interpolation.jpg which is a major
improvement.
>>>>
>
>>>>
> I have reviewed the code inside fluid_voice_dsp.c
and have set up my program
>>>>
> to emulate the equations. I converted the floating
point coefficients to
>>>>
> Q15 format. It seems to do exactly what it's
supposed to do. Yet I see no
>>>>
> improvement what-so-ever except at higher note
values.
>>>>
>
>>>>
> However...I don't see how linear interpolation can
work. If you have
>>>>
> straight lines (i.e. the "steps" in the first
waveform), a linear
>>>>
> interpolation won't change anything since the
current sample and the next
>>>>
> sample are the same over several samples.
>>>>
>
>>>>
> Are you up-sampling before you to do the linear
interpolation? I didn't see
>>>>
> any evidence in the code. Or do you simply take the
loop sample as is and
>>>>
> step through it using dsp_phase_index? I don't
think the bi-quad post
>>>>
> filter has an effect since it has a very high
cut-off. Nor should the
>>>>
> reverb or chorus blocks have any effect (since
they're disabled anyway in my
>>>>
> test).
>>>>
>
>>>>
> What am I missing?
>>>>
>
>>>>
> Thanks for your time and consideration. Any advice
or insight is
>>>>
> appreciated. I really like FluidSynth.
>>>>
>
>>>>
> Brad Stewart
>>>>
> P.S.I also implemented the 4th order
interpolation but it didn't change
>>>>
> anything--I still get the "stepped" waveform. (At
50MHz clock, the M4 can
>>>>
> process 128 samples in <1uS with sound fonts
stored in internal Flash
>>>>
> memory. Pretty impressive.)
>>>>
>
>>>>
>
>>>>
>
>>>>
>
>>>>
> Let me make sure I understand your situation
correctly.. So you have taken
>>>>
> the interpolation code in fluid_rvoice_dsp.c and
adapted it to integer math
>>>>
> and there is something wrong with the ported code,
since it is not
>>>>
> interpolating as expected.
>>>>
>
>>>>
> It has been a while since I delved into the
interpolation code and I did not
>>>>
> originally write it (though I did muck about in
that area a bit). If you
>>>>
> look at the fluid_rvoice_dsp_config() routine you
will see that it
>>>>
> initializes the interpolation tables, including
interp_coeff_linear, which
>>>>
> essentially stores 2 tables of linearly increasing
and decreasing values
>>>>
> from 0 to 1. These values are then used depending
on the current sample
>>>>
> index fraction (think of the current sample pointer
as being at a position
>>>>
> which may be in between 2 consecutive samples - the
fraction component). If
>>>>
> the fractional position is closer to the first
sample, then it will have a
>>>>
> higher weight in the linear calculation of the
sample value which gets
>>>>
> synthesized. I hope that makes sense and perhaps
you already knew this -
>>>>
> seeing as you have done this port.
>>>>
>
>>>>
> I would make sure that your ported code retains
this fractional sample
>>>>
> pointer component and is using it properly and that
your linear coefficients
>>>>
> table is properly initialized. You should be able
to see this stuff at work
>>>>
> by single stepping the code and looking at the
calculations to see if they
>>>>
> are behaving as expected.
>>>>
>
>>>>
> Hope that helps. Maybe I did not get your scenario
right though, if so,
>>>>
> please explain in more detail.
>>>>
>
>>>>
> Best regards,
>>>>
>
>>>>
> Element Green
>>>>
>
>>>>
>
>>>>
> _______________________________________________
>>>>
> fluid-dev mailing list
>>>>
> fluid-dev@nongnu.org
>>>>
> https://lists.nongnu.org/mailman/listinfo/fluid-dev
>>>>
>
>>>>
>
>>>>
> --
>>>>
>Brad Stewart
>>>>
>brads...@fastmail.us
>>>>
>
>>>>
>
>>>>
>
>>>>
>
>>>>
> _______________________________________________
>>>>
> fluid-dev mailing list
>>>>
> fluid-dev@nongnu.org
>>>>
> https://lists.nongnu.org/mailman/listinfo/fluid-dev
>>>>
>
>>>>
>
>>>>
>
>>>>
> _______________________________________________
>>>>
> fluid-dev mailing list
>>>>
> fluid-dev@nongnu.org
>>>>
> https://lists.nongnu.org/mailman/listinfo/fluid-dev
>>>>
>
>>>>
>>>>
_______________________________________________
>>>>
fluid-dev mailing list
>>>> fluid-dev@nongnu.org
>>>> https://lists.nongnu.org/mailman/listinfo/fluid-dev
>>>
>>>
>>>
>>> _______________________________________________
fluid-dev mailing list
>>> fluid-dev@nongnu.org
>>> https://lists.nongnu.org/mailman/listinfo/fluid-dev
>>
>>
>> _______________________________________________
>>
fluid-dev mailing list
>> fluid-dev@nongnu.org
>> https://lists.nongnu.org/mailman/listinfo/fluid-dev
>>
> _________________________________________________
> fluid-dev mailing list fluid-dev@nongnu.org
> https://lists.nongnu.org/mailman/listinfo/fluid-dev
--
Brad Stewart
brads...@fastmail.us
_______________________________________________
fluid-dev mailing list
fluid-dev@nongnu.org
https://lists.nongnu.org/mailman/listinfo/fluid-dev
