FFmpeg AMV Encoding Failure plain

Microsoft Windows [Version 6.1.7601]
Copyright (c) 2009 Microsoft Corporation.  All rights reserved.

D:\Users\User\Music\ConversionTests>ffmpeg -i sample.wmv -f amv sample.amv

ffmpeg version 0.9, Copyright (c) 2000-2011 the FFmpeg developers
  built on Dec 12 2011 15:34:57 with gcc 4.6.1
  configuration: --enable-gpl
  libavutil    51. 32. 0 / 51. 32. 0
  libavcodec   53. 42. 0 / 53. 42. 0
  libavformat  53. 24. 0 / 53. 24. 0
  libavdevice  53.  4. 0 / 53.  4. 0
  libavfilter   2. 53. 0 /  2. 53. 0
  libswscale    2.  1. 0 /  2.  1. 0
  libpostproc  51.  2. 0 / 51.  2. 0

Seems stream 1 codec frame rate differs from container frame rate: 1000.00
(1000/1) -> 29.97 (30000/1001)
Input #0, asf, from 'sample.wmv':
  Metadata:
    SfOriginalFPS   : 299
    WMFSDKVersion   : 11.0.6001.7000
    WMFSDKNeeded    : 0.0.0.0000
    IsVBR           : 0
    title           : Wildlife in HD
    copyright       : © 2008 Microsoft Corporation
    comment         : Footage: Small World Productions, Inc; Tourism New
Zealand | Producer: Gary F. Spradling | Mu
sic: Steve Ball
  Duration: 00:00:30.09, start: 0.000000, bitrate: 6977 kb/s
    Stream #0:0(eng): Audio: wmav2 (a[1][0][0] / 0x0161), 44100 Hz, 2
channels, s16, 192 kb/s
    Stream #0:1(eng): Video: vc1 (Advanced) (WVC1 / 0x31435657), yuv420p,
1280x720, 5942 kb/s, 29.97 tbr, 1k tbn, 1
k tbc
[NULL @ 039a7860] Requested output format 'amv' is not a suitable output format
sample.amv: Invalid argument

*********************************************************************************************************************

D:\Users\User\Music\ConversionTests>ffmpeg -i sample.wmv -r 16 -vf scale=176:128 -vcodec amv -qmin 3 -qmax 3 -acodec adpcm_ima_amv -ac 1 -ar

22050 -f amv sample.amv
ffmpeg version 0.9, Copyright (c) 2000-2011 the FFmpeg developers
  built on Dec 12 2011 15:34:57 with gcc 4.6.1
  configuration: --enable-gpl
  libavutil    51. 32. 0 / 51. 32. 0
  libavcodec   53. 42. 0 / 53. 42. 0
  libavformat  53. 24. 0 / 53. 24. 0
  libavdevice  53.  4. 0 / 53.  4. 0
  libavfilter   2. 53. 0 /  2. 53. 0
  libswscale    2.  1. 0 /  2.  1. 0
  libpostproc  51.  2. 0 / 51.  2. 0

Seems stream 1 codec frame rate differs from container frame rate: 1000.00
(1000/1) -> 29.97 (30000/1001)
Input #0, asf, from 'sample.wmv':
  Metadata:
    SfOriginalFPS   : 299
    WMFSDKVersion   : 11.0.6001.7000
    WMFSDKNeeded    : 0.0.0.0000
    IsVBR           : 0
    title           : Wildlife in HD
    copyright       : © 2008 Microsoft Corporation
    comment         : Footage: Small World Productions, Inc; Tourism New
Zealand | Producer: Gary F. Spradling | Mu
sic: Steve Ball
  Duration: 00:00:30.09, start: 0.000000, bitrate: 6977 kb/s
    Stream #0:0(eng): Audio: wmav2 (a[1][0][0] / 0x0161), 44100 Hz, 2
channels, s16, 192 kb/s
    Stream #0:1(eng): Video: vc1 (Advanced) (WVC1 / 0x31435657), yuv420p,
1280x720, 5942 kb/s, 29.97 tbr, 1k tbn, 1
k tbc

[NULL @ 01293e00] Requested output format 'amv' is not a suitable output format
sample.amv: Invalid argument