Write the smallest program performs a time stretch operation on a PCM Wave (.wav) file.
- Parameter input will by via whatever standard argument mechanism your language comes with, e.g.
$_GETin PHP. Hard coded paths are not allowed.
- First parameter will be a decimal value that represents the stretch coefficient. 1 means don't stretch, 2 means twice the length, 0.5 means half the length, 0.333 means one third the length. An example might be
stretch.exe 1.5 c:\sound.wav
- The time stretch operation does not need to perform pitch correction.
- You must not drop samples to fit a compression (i.e. stretch < 1). You should use interpolation, weighted mean, or a similar method.
- Assume a WAVE PCM file with a RIFF header.
- Assume 16-bits per sample (bonus if your code works for 8-bit and 24-bit audio)
- You must handle any number of audio channels.
- You must at least handle 11025, 22050 and 44100Hz sample rates, though the ability to handle arbitrary rates would be a bonus! :)
- Your output file must keep the same sample rate, sample size and channel count as the input file.
- The output file must be named "stretch.wav"
- You may not use any 3rd party libraries or built-in functions for audio processing. The parsing of the WAV file and the time stretch operation must be your own code.
On Windows, the
C:\Windows\Media directory contains plenty of WAV files to test with.