Converting MKV with 6ch AAC to AVI/MP4?

[Startropic1]

I'm having difficulty converting some mkv videos to avi or mp4 (either will work). The problem seems to be that the audio is 6-channel AAC. When I try to convert the video with handbrake, I get a video with garbled audio. I guess this means handbrake can't handle 6ch audio. I have tried demuxing the video and then converting the AAC to 2ch, but when I remux the converted audio with the video (which is divx5 btw) with virtualdub or MyMP4Box, the audio ends up going way out of sync.

Any suggestions on how to get this to work? Here's the mediainfo log:

General
Complete name : video.mkv
Format : Matroska
File size : 233 MiB
Duration : 23mn 48s
Overall bit rate : 1 368 Kbps
Movie name : video
Encoded date : UTC 2005-03-15 22:29:26
Writing application : mkvmerge v1.4.1 ('Cherry Lips') built on Mar 15 2005 09:58:06
Writing library : libebml v0.7.3 + libmatroska v0.7.5
Video
ID : 1
Format : MPEG-4 Visual
Format settings, BVOP : Yes
Format settings, QPel : No
Format settings, GMC : No warppoints
Format settings, Matrix : Default (H.263)
Codec ID : DX50
Codec ID/Hint : DivX 5
Duration : 23mn 48s
Width : 704 pixels
Height : 528 pixels
Display aspect ratio : 4:3
Frame rate : 23.976 fps
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Title : video
Writing library : DivX 5.2.0 (UTC 2004-07-15)
Language : Japanese
Audio #1
ID : 2
Format : AAC
Format/Info : Advanced Audio Codec
Format version : Version 4
Format profile : LC
Format settings, SBR : Yes
Format settings, PS : No
Codec ID : A_AAC/MPEG4/LC/SBR
Duration : 23mn 48s
Channel(s) : 6 channels
Sampling rate : 44.1 KHz
Title : English Audio
Language : English

[Baldrick]

Try another ffmpeg frontend, like xmedia recode, open mkv, under format choose avi, under video choose copy, under audio choose aac. Add job. Convert.