I have a wave file, i have a function that retrieves 2 samples per pixel then i draw lines with them. quick and painless before i deal with zooming. i can display the amplitude values no problem
that is an accurate image of the waveform. to do this i used the following code
//tempAllChannels[numOfSamples] holds amplitude data for the entire wav
//oneChannel[numOfPixels*2] will hold 2 values per pixel in display area, an average of min amp, and average of max
for(int i = 0; i < numOfSamples; i++)//loop through all samples in wave file
{
if (tempAllChannels[i] < 0) min += tempAllChannels[i];//if neg amp value, add amp value to min
if (tempAllChannels[i] >= 0) max += tempAllChannels[i];
if(i%factor==0 && i!=0) //factor is (numofsamples in wav)/(numofpixels) in display area
{
min = min/factor; //get average amp value
max = max/factor;
oneChannel[j]=max;
oneChannel[j+1]=min;
j+=2; //iterate for next time
min = 0; //reset for next time
max = 0;
}
}
and that's great but I need to display in db so quieter wave images arent ridiculously small, but when i make the following change to the above code
oneChannel[j]=10*log10(max);
oneChannel[j+1]=-10*log10(-min);
the wave image looks like this.
which isnt accurate, it looks like its being squashed. Is there something wrong with what I'm doing? I need to find a way to convert from amplitude to decibels whilst maintaining dynamics. im thinking i shouldnt be taking an average when converted to DB.
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