title: FFMPEG: MP4 videos are not playing properly in iPhone, iPod, iPad
body: <p>I am converting videos from m4v, flv to MP4 for iPhone, iPod, iPad.</p>
  
  <p>I am using the below command to convert these videos</p>
  
  <blockquote>
    <p>ffmpeg -y -i video_1336500693.m4v -vcodec libx264 -vpre slow -vpre
    ipod640 -b 250k -bt 50k -acodec libfaac -ab 56k -ac 2 -s 480x320
    video_1336500693.mp4</p>
  </blockquote>
  
  <p>The video part of this mp4 file is working fine but the audio is not working properly. I am using HTML5 for this.</p>
  
  <p>The audio works for first 8-10 seconds but after that audio does not work and the strange thing is if I jump to forward or backward the audio works.</p>
  
  <p>Can anyone suggest what's going wrong?</p>