well there's always math..... it's not too complicated if you know what's going on, and dependig on how your tracker defines offset (percentage, split points (ie each sample is split into 256 pieces for offset), or # of samples to offset. Some trackers will give you an interface to get the sample offset from a diagram, others will make you hunt and guess. It usually helps to have some kind of WAV editor handy when figuring out sample offsets. Manual calculations for finding the # of samples isn't al that useful, except in figuring out what a sample is, how it is stored, and why you need these numbers. Anyways, here's the math of Digital music.
* Here's the complex theory - Most programs will tell you the effective # of samples - Skip this if your does *
Any uncompressed music file will look similar to this to a music program.
Header (sampling info/filetype description, etc), Sample Data, Footer (sample terminator, additional info not in header)
therefore total # of bytes of sample data in the file = filesize - header size - footer size. Header/footer size can be variable though, so this is why most people use a program to do this kind of math.
total # of samples = bytes of sample data / (bit depth /
. Thus if you have a 16 bit sample, 16/8=2. 24 bit sample = 3, etc. 8 bit requires no math.
next, you need to divide the total number of samples by the number of channels playing - this is because the loop plays these channels back simultaneously. for stereo samples, divide total # of samples by 2 to get the # of effective samples. Mono samples require nothing to be done as they are 1 channel. 5.1 signals need to be divided by 6 - 5 satellite speakers and 1 subwoofer.
* Technical stuff over. Here's the important stuff *
Now you take your effective samples in the file. If you divide by the sample rate (typically 44100 samples per second these days, but 48000 is becoming more common) you get the number of seconds in the sample.This is less important, as you don't necessarily deal in seconds, but in beats.
Therefore, if you divide the number of effective samples by the number of beats in the loop (as in 1 bar is 4 beats, 2 bars is 8 beats, etc) you can find out how far apart your beats are in samples. the first beat will end at this number. Lets write an equasion:
x = (s/b) * (a-1)
s = effective samples in the loop
b = beats per loop
a = the beat in the loop you wish to start playing at
x = the sample offset required to playback your specific beat/start point
Therefore if you wish to play at beat 1 (Beginning of Loop), anything * 0 = 0, that's where you start. If you want to start at the second beat, s/b is where your first beat ends and your second begins. (s/b)*2 is where the third beat starts and so on... It works... Trust me
then there's tweaking of the sample offset... Rounding off your sample number is required, as you can't play half a sample... Because of this, often your beat loop may cause a pop. This is because the ends don't meet up on the waveform. Offsetting the start and/or cutting short the end of a waveform by around 100 samples or so won't affect the sound much, but will allow your waveform to meet at a central point that will avoid a pop. This is where your searching and tweaking is supposed to be. It should be small, and relatively easy to do....
Finding a beat is as simple as dividing your samples. Want greater accuracy? Adjust your math to fit your needs - Divide by 8 instead of 4. Beats are nice because by nature, they are evenly spaced. It's all a matter of how accurately you want to chop your beat up. There's no guess work, only tweaking to remove pops.
