Is modifying a song&#39;s audio using youtube&#39;s Phase Vococer to slow it down to 0.25% a copyright violation?
<p>On the surface, this seems like a simple question. At quick glance, you might immediately say: "Yes, changing the speed of a song is a derivative work". </p>

<p>According to <a href="https://en.wikipedia.org/wiki/Transformation_(law)" rel="nofollow noreferrer" title="Wikipedia">wikipedia</a>, a transformed work is possibly viewed as fair use: </p>

<blockquote>
  <p>In United States copyright law, transformation is a possible
  justification that use of a copyrighted work may qualify as fair use,
  i.e., that a certain use of a work does not infringe its holder's
  copyright due to the public interest in the usage. Transformation is
  an important issue in deciding whether a use meets the first factor of
  the fair-use test, and is generally critical for determining whether a
  use is in fact fair, although no one factor is dispositive.</p>
</blockquote>

<p>While it is completely clear that simply speeding up or slowing down a song, which would change both the pitch and speed, is clearly a derivative work. My question is regarding transforming it using youtube's speed controls. </p>

<p>Youtube's speed algorithm uses a <a href="https://en.wikipedia.org/wiki/Phase_vocoder" rel="nofollow noreferrer" title="phase vocoder">phase vocoder</a>. When the speed of a song is lowered to 0.25 it is virtually unrecognizable as the original work due to the effects the phase vocoder introduces to the original audio. The phase vocoder works by <strong>transforming</strong> the audio, which seems to match the legal language around what is considered fair use. In fact, the basis for a phase vocoder is a mathematical transformation  function called a <a href="https://en.wikipedia.org/wiki/Short-time_Fourier_transform" rel="nofollow noreferrer" title="Short-time Fourier Transform">Short-time Fourier transform</a>. </p>

<p>In youtube's speed control algorithm, while the pitch is retained, the duration of the notes is altered, and the effect of of the phase vocoder on slowing the video to 0.25 adds audio effects that transforms even the color of the notes to the point that it's difficult to tell what instrument is being played. </p>

<p>Further, once this transformation is performed on the audio, if a recording is made of the audio in this state, returning it to the original speed is a near impossibility. </p>

<p>Also, the reason I'm asking this overall, is I would like to do this and then add several layers of tracks of different instruments and effects to the song, which could be considered criticism or parody perhaps? </p>

<p>Not legal. YouTube's description of the vocoder as "transforming" the audio is not talking about transformation in the same sense as copyright law.</p>

<p>Although I suppose it could be possible, I don't see how you could have a transformative use without at least the same degree of originality required for the underlying work to receive copyright protection. Because you're just running the song through an algorithm, there's no originality involved. </p>

<p>As for the final product you're talking about, I think you're getting closer to fair-use territory, but it's hard to make a solid assessment without the actual materials.</p>

copyright music