First you will require the fcchandler WMV filter
in the plugins folder in order for VirtualDub to index the ASF file VirtualDub will still show MISSING CODEC after the ffcchandler has parsed the file for use, you may still be able to hear the audio that might be in WMA format you may also need to check the audio lead OR lag this can be adjusted in the advanced settings.
Two options are available to you for the WMV3 (Windows Media Video 9) download the wmv9VCMsetup.exe
this will give you the required VCM (Video Compression Manager) for WMV3 only the WMV1 (Windows Media Video 7) and WMV2 (Windows Media Video 8) were exclusively intended for use with the ASF/WMV container and the DirectShow architecture. Microsoft won’t allow any encoding, decoding, or editing outside their own software without licensing and only release the WMP9 VCM through popular demand you will have to use the ffdshow filter for these.
If you want to re-encode the WMP7 and WMP8 formats I would download the ffdshow filter
and set in the VFW Configuration settings for WMV to use the libavcodec
GPL open source free codec library
Check out this SITE
for more info on the Simple WMP9 and Advanced VC-1 profiles if you are interested for me the WMV is obsolete since MPG4 can on the scene even Sky and iPlayer use MP4 now due to is small download size.
When you have reassigned FOURCC to the libavcodec for WMV1 and 2 VirtualDub will then be able to use the ffdshow Video codec to re-encode the ASF file VirtualDub will see the VCM as the ffdshow Video Codec as shown below.
Don't forget to select the compression method I use DivX Home Video format the PCM audio is set as default so a can watch them on my standalone DVD player using the uncompressed audio will give you the best synch results. You can use the more popular and smaller AC3 or MP3 codecs but you will have mixed results depending upon the WMA audio codec anything above V2 should be ok and error free when re-encoding to your desired audio stream.
It may take a few goes to make sure that the audio is in synch for the re-encode but take time to make using the preview to make sure it is correct and add the correct millisecs of delay, you may hit it first time
It's also a good idea to install the MPG4 Windows Codec right clicking on the INF file in this mpg4vki.zip
to ensure that you can play them on normal media players
If you plan on using the popular MPG4 codec DivX now at v6.9.1 then you must disable this FOURCC within the ffdshow video decoder otherwise you will encode a DIVX or DX50 file with sound an blank video let the DivX Professional Codec do the talking If you plan on using the other popular MPG4 option the Xvid is already in the libavcodec so you can select either as shown below the blue marked must be disabled if you want to use DivX Pro and WMP9VCM, the WMP7+8 shown in red using the libavcodec's
There is a difference the DECODER is FFv in RED and the ENCODER is FFe in BROWN is the video encoder as shown above selected on the VWF configuration menu option from ffdshow is what needs to be changed for VirtualDub's ASF and WMV needs.