Hi, i found the following DSP code for c from a link in this thread and i want to use it in delphi.
I know that there is a similar function in bass_fx20alpha but i want to try it
The C code was
Here's a simple dynamic amplification DSP...
#define amptarget 30000 // target level
#define ampquiet 800 // quiet level
#define amprate 0.02f // amp adjustment rate
typedef struct {
float gain; // amplification level
int delay; // delay before increasing level
int count; // count of sequential samples below target level
int high; // the highest in that period
int quiet; // count of sequential samples below quiet level
} AUTOAMPSTUFF;
void CALLBACK autoamp(HDSP handle, DWORD channel, void *buffer, DWORD length, AUTOAMPSTUFF *amp)
{
short *data=(short*)buffer;
DWORD c;
for (c=0;c<length/2;c++) {
int s=(int)(data[c]*amp->gain); // amplify sample
int sa=abs(s);
if (abs(data[c])<ampquiet)
amp->quiet++; // sample is below quiet level
else
amp->quiet=0;
if (sa<amptarget) { // amplified level is below target
if (sa>amp->high) amp->high=sa;
amp->count++;
if (amp->count==amp->delay) { // been below target for a while
if (amp->quiet>amp->delay)
// it's quiet, go back towards normal level
amp->gain+=10*amprate*(1-amp->gain);
else
amp->gain+=amprate*amptarget/amp->high; // increase amp
amp->high=amp->count=0; // reset counts
}
} else { // amplified level is above target
if (s<-32768) s=-32768;
else if (s>32767) s=32767;
amp->gain-=2*amprate*sa/amptarget; // decrease amp
amp->high=amp->count=0;
}
data[c]=(short)s; // replace original sample with amplified version
}
}
...
AUTOAMPSTUFF amp;
amp.gain=1;
amp.delay=BASS_ChannelSeconds2Bytes(handle,1)/2;
amp.count=amp.high=amp.quiet=0;
BASS_ChannelSetDSP(handle,(DSPPROC*)&autoamp,&);
I managed to go this far because of some knowladge in PHP but i don't know what to use instead of
data[c] to read the samples
type
TAUTOAMPSTUFF = record
gain: float; // amplification level
delay: Integer; // delay before increasing level
count: Integer; // count of sequential samples below target level
high: Integer; // the highest in that period
quiet: Integer; // count of sequential samples below quiet level
end;
.....
implementation
var
amp:TAUTOAMPSTUFF;
const
amptarget = 30000; // target level
ampquiet = 800; // quiet level
amprate = 0.02; // amp adjustment rate
procedure DynamicAmp(handle: HDSP; channel: DWORD; buffer: Pointer; length: DWORD; user: DWORD); stdcall;
var
c: DWORD;
data: PSingle;
S,sa: Integer;
begin
data := buffer;
c := 0;
for c := 0 to (length div 2) do
begin
s := data[c] * (amp.gain)); // amplify sample
sa := abs(s);
if ((abs(data[c])) < (ampquiet)) then inc(amp.quiet) // sample is below quiet level
else amp.quiet := 0;
if (sa < amptarget) then // amplified level is below target
begin
if (sa > amp.high) then amp.high := sa;
inc(amp.count);
if (amp.count = amp.delay) then // been below target for a while
begin
if (amp.quiet > amp.delay) then // it's quiet, go back towards normal level
amp.gain := amp.gain + (10 * amprate * (1 - amp.gain))
else amp.gain := amp.gain + (amprate * amptarget / amp.High); // increase amp
amp.high := 0; // reset counts
amp.count := 0;
end;
end
else // amplified level is above target
begin
if s > 32767 then s := 32767
else if s > 32767 then s := 32767;
amp.gain := amp.gain - (2 * amprate * sa / amptarget); // decrease amp
amp.high := 0;
amp.count := 0;
end;
data[c]=s; // replace original sample with amplified version
end;
end;
Thank you
Alex
