Converting MP4 to AVI - Confusing Audio Problem

[visibility]

I have an MP4 file that I wish to convert to AVI format but there is a problem with the audio. The video will play in a variety of players including Windows Media Player but there is no sound. It plays correctly in VLC Media Player - both video and audio. I consequently assumed this was a codec issue. GSpot reports Codec Status Undertermined for both the video and audio codecs! The MP4 file uses avc1 for video and ac-3 for audio. I installed AC3Filter as I read on another forum this worked under Win 7. This actually didn't work for me and GSPot reported exactly the same. In desperation I tried the audio codecs from ffdshow and this also failed. MediaInfo just seems to confirm what GSpot showed so I'm not sure that either app is helpful in this scenario.

I went ahead with the MP4 to AVI conversion anyway using AVS Video Converter 6.4 and after an hour or two I found the video rendered nicely but there was, again, no audio (not even in VLC).

So now I am completely stumped. Is this a codec issue? Is the MP4 file damaged? Is there a better way to vonvert this MP4 to AVI format that has a better chance of success? The reason for converting to AVI is to eventually burn to a DVD and perhaps there is a more direct route to this?

Thanks for your help.

[poisondeathray]

vlc uses internal codecs/splitters, wmp relies on system installed ones

ac3 audio was added to .mp4 container specs about a year ago, but many splitters still haven't been updated - the one you are using probably doesn't

by "splitter" I don't mean cuts into pieces, I mean filter that parses video and splits audio & video streams and allows that to connect to the decoder like ac3filter or ffdshow. Right now if you were to render the mp4 file in graphedit, it probably doesn't connect to the filter.

You need to install a newer directshow mp4 splitter that supports ac3 audio . You can either download from mpchc project and register it or the other link. You could use radlight filter manage to register the mp4 splitter . I think newer versions of haali media splitter support it as well if you configure it properly
http://sourceforge.net/projects/mpc-hc/files/
http://sourceforge.net/projects/guliverkli2/files/DirectShow%20Filters/

If you don't want to install filters or "fix" your directshow subsystem, there are other ways to convert that don't rely on directshow .eg. avisynth with ffmpegsource2 and any encoder that accepts avisynth scripts

There are other ways to convert too , that don't rely on directshow, e.g. ffmpeg (or gui's for it like winff) , or avidemux

You could probably "copy" the audio as ac3 and just convert the video , if you didn't want to lose audio quality . This conversion would be easy to do in avidemux

[visibility]

Thanks for the information. Very helpful.

[visibility]

Thanks for the information. Very helpful.

I registered the MP4 splitter with Radlight Filter Manager and unfortunately the audio still refused to play. But with your updated info I have been able to use winff to convert. It is converting as I write this but a preview played properly with audio so I am hopeful. Avidemux looks interesting and I will check that out as well.

[Bonie81]

it would be easy for anyone to assist you, if you have posted mediainfo for mp4 files.
mp4 can be converted easily with AVIDemux or FreeMP4-2-AVI Converter.