Why Avisynth can not get the audio info from wmv.

[chatfuns]

i save the following scripts to file convert.avs.

DirectShowSource("livemeeting.wmv")
return last

//end

then i use ffmpeg to get the file info like:
ffmpeg -i convert.avs

return

Input #0, avs, from 'e:\temp\downloadLMM\convert.avs':
Duration: 00:00:10.0, start: 0.000000, bitrate: 0 kb/s
Stream #0.0: Video: rawvideo, rgb32, 552x56, 23740 kb/s, 24.00 fps(r)
Must supply at least one output file.

not audio stream was found.
but i use mediainfo can get the info like:

General #0
Complete name : E:\temp\downloadLMM\livemeeting.wmv
Format : Windows Media
File size : 6.59 MiB
PlayTime : 59mn 19s
Bit rate : 16 Kbps
Movie name : Microsoft Office System Webcast: Driving Towards a Deadline: Kno
Recorded date : 2005
Comment : Microsoft Office LiveMeeting 2005 Replay. Recorded on Tuesday, December 13, 2005 10:04:24 AM PST
Date_Created : UTC 2049-06-03 22:58:36

Video #0
Codec : Windows Media
Codec/Info : Windows Media 9
Width : 704 pixels
Height : 528 pixels
Aspect ratio : 4/3
Resolution : 24 bits

Audio #0
Codec : WMSpeech
Bit rate : 8000 bps
Channel(s) : 1 channel
Sampling rate : 8000 Hz

How can i get the audio info by this way.

[chatfuns]

any one want test this question can get the wmv file form the following link.

http://msevents.microsoft.com/cui/WebCastEventDetails.aspx?culture=en-US&EventID=1032285347&CountryCode=US

[IanB]

Add the Info() filter to your script to display the internal state of your Avisynth graph.

From this you can determine if DirectShowSource() is not accepting the Audio stream or ffmpeg is not accepting the Audio stream from the AviFile interface.

If Info() reports there is no Audio. Then doDirectShowSource("livemeeting.wmv", video=false, logfile="Blah.log")and post the "Blah.log" file here for someone to analysis (Zip it up and attach it, if it is more than few Kb long).

If Info() reports there is Audio in your Avisynth graph. Then open "convert.avs" in VirtualDub, display the stream properties, File->Info. If VDub can find the audio stream then seek a ffmpeg guru.