Audio playback, creating nested loop for fade in/out.
- by Dave Slevin
Hi Folks,
First time poster here.
A quick question about setting up a loop here. I want to set up a for loop for the first 1/3 of the main loop that will increase a value from .00001 or similar to 1. So I can use it to multiply a sample variable so as to create a fade-in in this simple audio file playback routine.
So far it's turning out to be a bit of a head scratcher, any help greatfully recieved.
for(i=0; i < end && !feof(fpin); i+=blockframes)
{
samples = fread(audioblock, sizeof(short), blocksamples, fpin);
frames = samples;
for(j=0; j < frames; j++)
{
for (f = 0; f< frames/3 ;f++)
{
fade = fade--;
}
output[j] = audioblock[j]/fade;
}
fwrite(output,sizeof(short), frames, fpoutput);
}
Apologies,
So far I've read and re-write the file successfully. My problem is I'm trying to figure out a way to loop the variable 'fade' so it either increases or decreases to 1, so as I can modify the output variable.
I wanted to do this in say 3 stages:
1. From 0 to frames/3 to increace a multiplication factor from .0001 to 1
2. from frames 1/3 to frames 2/3 to do nothing (multiply by 1) and
3. For the factor to decrease again below 1 so as for the output variable to decrease back to the original point.
How can I create a loop that will increase and decrease these values over the outside loop?
