Need Instrument Sample Files with Looping Info

[synthdsw]

I am developing an iPad app that, among other things, plays MIDI files. My programmer found some free instrument sample audio files, and explained to me that to play an instrument sound the app takes a sample file (a short audio file like a wav, aiff, or caf file), transposes it into the correct key, and then plays it for the requested duration. He explained that to get the right duration, the sampler needs to loop parts of the file, but normally it shouldn't loop the whole file, but only a region in the middle of the file. Thus, the sampler needs to know which region to loop. He explained that wav, aiff, and caf files all provide the means to embed looping information. He has been looking for royalty-free instrument sample audio files with embedded looping info, but he hasn't found any. I'd be grateful if someone could point me to such files, or if there are no such royalty-free files, then to a library that we can license for distribution with our app. Thanks!

[jlewin]

I am developing an iPad app that, among other things, plays MIDI files. My programmer found some free instrument sample audio files, and explained to me that to play an instrument sound the app takes a sample file (a short audio file like a wav, aiff, or caf file), transposes it into the correct key, and then plays it for the requested duration. He explained that to get the right duration, the sampler needs to loop parts of the file, but normally it shouldn't loop the whole file, but only a region in the middle of the file. Thus, the sampler needs to know which region to loop. He explained that wav, aiff, and caf files all provide the means to embed looping information. He has been looking for royalty-free instrument sample audio files with embedded looping info, but he hasn't found any. I'd be grateful if someone could point me to such files, or if there are no such royalty-free files, then to a library that we can license for distribution with our app. Thanks!

Not sure what you're looking for - there are all sorts of loop libraries available, both commercial and freeware - but if you're planning on the sounds via midi, wouldn't you want to trigger individual sampled sounds, instead of complete loops? Samplers will also loop sustained sections so you can hold a note as long as you like. Is that what you're looking for?

[synthdsw]

Thanks for your reply. What I mean is, if I am playing a piano sound for 1sec, and I have an audio file of a piano sound that is 1sec long, then I just play the whole audio file. And if I need .5sec, then I just play the first half of the audio file. But if I need to play the piano sound for 2.3 sec, I start playing the beginning of the audio file, but at some time offset x in the audio file I loop back to an earlier offset of x-y which is somewhere between the beginning of the audio file and x, and keep doing this until 2.3 sec has passed. What my programmer has said is that while he is finding audio files of instrument sounds, he is not finding such files with looping information (i.e., x and x-y ) embedded within them, although he says that wav, aiff, and caf file formats support such embedding of looping information. And without this looping information, picking x and x-y at random usually results in a poor loop with a click being sounded with each loop.