Epic->yoshimax

$ ffmpeg -i "stream1125884022109_video.flv" -b 360 -r 29.97 -hq -ab 128 -ar 44100 -an "outputfile.avi"
ffmpeg version 0.4.9-pre1, build 4755, Copyright (c) 2000-2004 Fabrice Bellard
configuration:
built on Jun 6 2005 19:59:56, gcc: 3.3.3 20040412 (Red Hat Linux 3.3.3-7)
[flv @ 0x830d484]Unsupported audio codec (5)

Seems that stream 1 comes from film source: 1000.00 (1000/1) -> 31.25 (125/4)
Input #0, flv, from 'stream1125884022109_video.flv':
Duration: N/A, bitrate: N/A
Stream #0.0: Audio: 0x0005, 8000 Hz, mono
Stream #0.1: Video: flv, yuv420p, 160x120, 1000.00 fps
File 'outputfile.avi' already exists. Overwrite ? [y/N] y
Output #0, avi, to 'outputfile.avi':
Stream #0.0: Video: mpeg4 (hq), yuv420p, 160x120, 29.97 fps, q=2-31, 360 kb/s
Stream mapping:
Stream #0.1 -> #0.0
[mpeg4 @ 0x8396f54]removing common factors from framerate
Press [q] to stop encoding
frame= 217 q=0.0 Lsize= 286kB time=7.2 bitrate= 323.0kbits/s
video:94kB audio:0kB global headers:0kB muxing overhead 203.316631%

-anという disable audio オプションをつけると変換できるのですが、

$ ffmpeg -i "stream1125884022109_video.flv" -b 360 -r 29.97 -hq -ab 128 -ar 44100 "outputfile.avi"
ffmpeg version 0.4.9-pre1, build 4755, Copyright (c) 2000-2004 Fabrice Bellard
configuration:
built on Jun 6 2005 19:59:56, gcc: 3.3.3 20040412 (Red Hat Linux 3.3.3-7)
[flv @ 0x830d484]Unsupported audio codec (5)

Seems that stream 1 comes from film source: 1000.00 (1000/1) -> 31.25 (125/4)
Input #0, flv, from 'stream1125884022109_video.flv':
Duration: N/A, bitrate: N/A
Stream #0.0: Audio: 0x0005, 8000 Hz, mono
Stream #0.1: Video: flv, yuv420p, 160x120, 1000.00 fps
File 'outputfile.avi' already exists. Overwrite ? [y/N] y
Output #0, avi, to 'outputfile.avi':
Stream #0.0: Video: mpeg4 (hq), yuv420p, 160x120, 29.97 fps, q=2-31, 360 kb/s
Stream #0.1: Audio: mp2, 44100 Hz, mono, 128 kb/s
Stream mapping:
Stream #0.1 -> #0.0
Stream #0.0 -> #0.1
[mpeg4 @ 0x8396f54]removing common factors from framerate
Unsupported codec (id=0) for input stream #0.0

オーディオ付だとエラーる。

[flv @ 0x830d484]Unsupported audio codec (5)

Seems that stream 1 comes from film source: 1000.00 (1000/1) -> 31.25 (125/4)
Input #0, flv, from 'stream1125884022109_video.flv':
Duration: N/A, bitrate: N/A
Stream #0.0: Audio: 0x0005,

んー、どうすればよいのか。。。
(また、解決方法が載らない無駄スレになってしまうのか。。。)