iOS : How to apply audio effect on recorded video
<p>I am developing an application which require to apply audio effect on recorded video.</p>

<p>I am recording video using GPUImage library. I can successfully done with it. Now, I need to apply audio effect like Chipmunk, Gorila, Large Room, etc.</p>

<p>I looked into Apple's document and it say that AudioEngine can't apply AVAudioUnitTimePitch on Input Node (as Microphone).</p>

<p>For solving this problem, I use following mechanism.</p>

<ul>
<li>Record video &amp; audio at same time.</li>
<li><p>Play video. While playing video, start AudioEngine on Audio file and apply <strong>AVAudioUnitTimePitch</strong> on it.</p>

<p><code>[playerNode play]; // Start playing audio file with video previ</code>ew</p></li>
<li><p>Merge video and new effected audio file.</p></li>
</ul>

<p><strong>Problem :</strong></p>

<ul>
<li>User have to preview a full video for audio effect merge. This is not a good solution.
If I set <strong>volume of playerNode to 0 (zero)</strong>. Then It record mute video.</li>
</ul>

<p>Please provide any better suggestion to do this things. Thanks in advance.</p>