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ultrus

Generating .wav files using php

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PHP amazed me yet again with the ability to generate .wav files. One can take two or more .wav files and merge them together as seen at http://articles.techrepublic.com.com/5100-3513_11-5810215.html . It is also possible to apply effects to audio files like echo, fade, and crop like seen in the great php class at http://www.pviet.com/wavedit/test_wavedit.html.php (even comes with a wave form image maker!). More info on the actual .wav format can be seen at
http://ccrma.stanford.edu/CCRMA/Courses/422/projects/WaveFormat/ (still a bit greek to me)

I want to expand on this in my own fun projects. Using the second example from above, how can I generate my own audio files from scratch? It would be cool to generate raw audio data arrays using mathmatic equations, and create a file that will play in an audio player. Here is what I have added to the class so far with further questions  commented:

[code]
function makeFile($dataArray) {
//set name
$this->afiles[0]['name'] = "scratchFile.wav";
$this->wavs['ChunkID'] = "RIFF";
$this->wavs['ChunkSize'] = 83140; //how do I set this? I just pulled this number from an existing file. How do I  get this for one that does not exsist yet?
$this->wavs['Format'] = "WAVE";
$this->wavs['Subchunk1ID'] = "fmt";
$this->wavs['SubChunk1Size'] = 16;
$this->wavs['AudioFormat'] = 1;
$this->wavs['NumChannels'] = 1;
$this->wavs['SampleRate']  = 16000;
$this->wavs['ByteRate'] = 32000;
$this->wavs['BlockAlign'] = 2;
$this->wavs['BitsPerSample'] = 16;

$this->wavs['Subchunk2ID'] = "data";
$this->wavs['SubChunk2Size'] = 83104; //how do I set this?  This is an example from an exsisting file.
//$this->wavs['Data']= ""; //how? is a string, from data above? Can I skip this? assuming yes for now

$this->wavs['NumberSamples']= ($this->wavs['SubChunk2Size']*8)/($this->wavs['NumChannels']*$this->wavs['BitsPerSample']);

                $this->afiles[0]['structure'] = $this->wavs;
//$this->getDataArr($this->unpackData($this->wavs['Data']));
$this->afiles[0]['arrdata']= $dataArray;
}
[/code]

This is a bit of an odd request compared to what I normally experiment with. Any feedback from the smart or inspired people out there would be greatly appriciated. :)

Thank you,

Ultrus

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Answered my own question. :)

A great class that generates .wav files from scratch can be found at:
http://www.phpclasses.org/browse/package/1932.html

It currently only generates sine waves, but it's a great start! Hope someone else enjoys this.

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