title: Re-sampling H264 video to reduce frame rate while maintaining high image quality
body: <p>Here's the mplayer output for a video of interest:</p>
  
  <pre><code>br@carina:/tmp$ mplayer foo.mov 
  mplayer: Symbol `ff_codec_bmp_tags' has different size in shared object, consider re-linking
  MPlayer 1.0rc4-4.5.2 (C) 2000-2010 MPlayer Team
  mplayer: could not connect to socket
  mplayer: No such file or directory
  Failed to open LIRC support. You will not be able to use your remote control.
  
  Playing foo.mov.
  libavformat file format detected.
  [lavf] stream 0: video (h264), -vid 0
  [lavf] stream 1: audio (aac), -aid 0, -alang eng
  VIDEO:  [H264]  1280x720  24bpp  59.940 fps  2494.2 kbps (304.5 kbyte/s)
  ==========================================================================
  Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family
  Selected video codec: [ffh264] vfm: ffmpeg (FFmpeg H.264)
  ==========================================================================
  ==========================================================================
  Opening audio decoder: [faad] AAC (MPEG2/4 Advanced Audio Coding)
  AUDIO: 44100 Hz, 2 ch, s16le, 128.0 kbit/9.07% (ratio: 15999-&gt;176400)
  Selected audio codec: [faad] afm: faad (FAAD AAC (MPEG-2/MPEG-4 Audio))
  ==========================================================================
  AO: [pulse] 44100Hz 2ch s16le (2 bytes per sample)
  Starting playback...
  Movie-Aspect is 1.78:1 - prescaling to correct movie aspect.
  VO: [vdpau] 1280x720 =&gt; 1280x720 Planar YV12
  </code></pre>
  
  <p>I'd like to use ffmpeg, mencoder, or some other command-line video transcoder to re-sample this video to a lower framerate without loss of <em>image</em> quality. That is, each frame should remain as crisp as possible.</p>
  
  <h2>Attempts</h2>
  
  <pre>ffmpeg -i foo.mov -r 25 -vcodec copy bar.mov</pre>
  
  <ul>
  <li>The target frame rate -- 25fps -- is achieved but individual frames are "blocky."</li>
  </ul>
  
  <pre>mencoder -nosound -ovc copy foo.mov -ofps 25 -o bar.mov</pre>
  
  <ul>
  <li>Videos are effectively un-viewable.</li>
  </ul>
  
  <h2>Help!</h2>
  
  <p>This seems like a simple enough use case. I'm very surprised that obvious things are not working. Is there something wrong with my approach?</p>