ubuntu@ubuntu:~$ avconv -i MVI_3073.AVI -pass 1 -pre libvpx-canon -vcodec libvpx -an -f webm -y test.webm
avconv version 0.8.7-6:0.8.7-1ubuntu1, Copyright (c) 2000-2013 the Libav developers
  built on Jul 23 2013 11:29:34 with gcc 4.8.1
Input #0, avi, from 'MVI_3073.AVI':
  Metadata:
    creation_time   : 2013-08-27 08:46:49
    encoder         : CanonMVI06
  Duration: 00:00:04.13, start: 0.000000, bitrate: 10313 kb/s
    Stream #0.0: Video: mjpeg, yuvj422p, 640x480, 30 tbr, 30 tbn, 30 tbc
    Stream #0.1: Audio: pcm_s16le, 44100 Hz, 2 channels, s16, 1411 kb/s
Incompatible pixel format 'yuvj422p' for codec 'libvpx', auto-selecting format 'yuv420p'
[buffer @ 0x1cb23a0] w:640 h:480 pixfmt:yuvj422p
[avsink @ 0x1cad620] auto-inserting filter 'auto-inserted scaler 0' between the filter 'src' and the filter 'out'
[scale @ 0x1cadd00] w:640 h:480 fmt:yuvj422p -> w:640 h:480 fmt:yuv420p flags:0x4
[libvpx @ 0x1cb0820] v1.2.0
Output #0, webm, to 'test.webm':
  Metadata:
    creation_time   : 2013-08-27 08:46:49
    encoder         : Lavf53.21.1
    Stream #0.0: Video: libvpx, yuv420p, 640x480, q=0-63, pass 1, 3000 kb/s, 1k tbn, 30 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (mjpeg -> libvpx)
Press ctrl-c to stop encoding
frame=   30 fps=  0 q=0.0 size=       0kB time=10000000000.00 bitrate=   0.0kbitframe=   60 fps= 59 q=0.0 size=       0kB time=10000000000.00 bitrate=   0.0kbitframe=   90 fps= 59 q=0.0 size=       0kB time=10000000000.00 bitrate=   0.0kbitframe=  118 fps= 58 q=0.0 size=       0kB time=10000000000.00 bitrate=   0.0kbitframe=  124 fps= 58 q=0.0 Lsize=       0kB time=10000000000.00 bitrate=   0.0kbits/s    
video:0kB audio:0kB global headers:0kB muxing overhead inf%
ubuntu@ubuntu:~$ avconv -i MVI_3073.AVI -pass 2 -pre libvpx-canon -vcodec libvpx -an -f webm -y test.webm
avconv version 0.8.7-6:0.8.7-1ubuntu1, Copyright (c) 2000-2013 the Libav developers
  built on Jul 23 2013 11:29:34 with gcc 4.8.1
Input #0, avi, from 'MVI_3073.AVI':
  Metadata:
    creation_time   : 2013-08-27 08:46:49
    encoder         : CanonMVI06
  Duration: 00:00:04.13, start: 0.000000, bitrate: 10313 kb/s
    Stream #0.0: Video: mjpeg, yuvj422p, 640x480, 30 tbr, 30 tbn, 30 tbc
    Stream #0.1: Audio: pcm_s16le, 44100 Hz, 2 channels, s16, 1411 kb/s
Incompatible pixel format 'yuvj422p' for codec 'libvpx', auto-selecting format 'yuv420p'
[buffer @ 0x24cc3a0] w:640 h:480 pixfmt:yuvj422p
[avsink @ 0x24c7620] auto-inserting filter 'auto-inserted scaler 0' between the filter 'src' and the filter 'out'
[scale @ 0x24c7d00] w:640 h:480 fmt:yuvj422p -> w:640 h:480 fmt:yuv420p flags:0x4
[libvpx @ 0x24ca820] v1.2.0
Output #0, webm, to 'test.webm':
  Metadata:
    creation_time   : 2013-08-27 08:46:49
    encoder         : Lavf53.21.1
    Stream #0.0: Video: libvpx, yuv420p, 640x480, q=0-63, pass 2, 3000 kb/s, 1k tbn, 30 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (mjpeg -> libvpx)
Press ctrl-c to stop encoding
[webm @ 0x24ca040] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 33 >= 33
av_interleaved_write_frame(): Invalid argument