title: Error while opening encoder for output stream #0:1 - maybe incorrect parameters such as bit_rate, rate, width or height
body: <p>I am trying to convert an avi video file to flv format via FFMPEG with the following command:</p>
  
  <pre><code>-i C:\files\input\test.avi -y -ab 448k -ar 48000 -vcodec mpeg4 -s 640x480 -f flv C:\files\output\test.flv
  </code></pre>
  
  <p>Here is the response I am getting from ffmpeg:</p>
  
  <p>Input:</p>
  
  <pre><code>Input #0, avi, from 'C:\files\input\test.avi':
    Metadata:
      encoder         : VirtualDubMod 1.5.10.2 (build 2540/release)
    Duration: 00:01:00.00, start: 0.000000, bitrate: 1813 kb/s
      Stream #0:0: Video: mpeg4 (Advanced Simple Profile) (XVID / 0x44495658), yuv420p, 640x272 [SAR 1:1 DAR 40:17], 25 tbr, 25 tbn, 25 tbc
      Stream #0:1: Audio: ac3 ([0] [0][0] / 0x2000), 48000 Hz, 5.1(side), s16, 448 kb/s
  </code></pre>
  
  <p>Output:</p>
  
  <pre><code>Output #0, flv, to 'C:\files\output\test.flv':
    Metadata:
      encoder         : VirtualDubMod 1.5.10.2 (build 2540/release)
      Stream #0:0: Video: mpeg4, yuv420p, 640x480 [SAR 30:17 DAR 40:17], q=2-31, 200 kb/s, 90k tbn, 25 tbc
      Stream #0:1: Audio: mp3, 48000 Hz, 5.1(side), s16, 448 kb/s
  Stream mapping:
    Stream #0:0 -&gt; #0:0 (mpeg4 -&gt; mpeg4)
    Stream #0:1 -&gt; #0:1 (ac3 -&gt; libmp3lame)
  Error while opening encoder for output stream #0:1 - maybe incorrect parameters such as bit_rate, rate, width or height
  </code></pre>
  
  <p>Can you tell me what is MAY BE here? and what is wrong above? </p>