title: KTX vs DDS images in OpenGL
body: <p>I used DDS (DXT5)till now for fast load of texture data.Now,I <a href="http://www.khronos.org/opengles/sdk/tools/KTX/" rel="nofollow">read</a> that since OpenGL 4.3 (and for ES2) the compressed standard is KTX(ETC1/ETC2).I integrated the Khronos libktx SDK and bench-marked.
  Updating texture using  <strong>glCompressedTexSubImage2D</strong>  for 3000 times the results are:</p>
  
  <p>DDS:
  1450 - millisecond</p>
  
  <p>KTX - forever....</p>
  
  <p>Actually, running a loop of only 300 times updating KTX, the total time already reaches 24 seconds!</p>
  
  <p>Now I have 2 questions:</p>
  
  <ol>
  <li><p>Is this the expected speed of KTX?</p></li>
  <li><p>if the answer to the first question is "YES" then what is the advantage of ETC except of smaller file size than that of DDS? </p></li>
  </ol>
  
  <p>I use OpenGL 4.3 with Quadro4000 GPU.</p>