What does it contain would you happen to know?

WM9Codecs9x is not a general "codec package". It only contains updated Microsoft Windows Media codecs for playback of its associated files, as explained by j7n.

Wiki-Wiki... Your "MP4" file would not play with the MS Codecs probably because the format is newer than the MS implementation, hence the need for FFDSHOW/Nero Codecs.

Wiki - WMP may help you to understand why you need other software/codecs for WMP9 for Win9x...

This explains MP9/MP10 for XP/etc.

So... depends on how it's ENCODED in order to DECODE it...

edit (what you downloaded from MS) -

Codec Installation Package for Windows Media Player 7.1 or later contains the following codecs :

- Windows Media Audio 9

- Windows Media Screen 9

- Windows Media Audio 9 Voice

- Windows Media Video 7, 8, and 9

- Microsoft MPEG-4 version 3

- Microsoft MPEG-4 version 1 and 2

- ISO MPEG-4 version 1 and 1.1

edit (again) - did you ever look here which has a link to here?

edit (last time, I promise) - you're problem has been solved, correct? Please mark this topic as such...

Edited May 5, 201214 yr by submix8c

Nero installs components for MPEG-4 playback. To see which codecs are in use during playback, run Windows Media Player (mplayer2.exe), and look at the stream properties (screenshot). You want to see ffdshow there for good quality playback.

Thanks for your post.

I have checked this, and when I play an mp4 using mplayer2 this is what I see below after checking properties. when using the mplayer2.exe

It is an exe installer, but because of my web hosting I had to chage the extension to .ex_, which I thought would be obvious. Rename it and run it.

I see, thanks.

I haven't required to install that splitter yet, will I need to for any reason?

The screenshot looks alright. Ffdshow is being used for both video and audio, and the MP4 splitter is invisible because it doesn't have a property dialog. Haali splitter hasn't been installed.

Haali Media Splitter has very high compatibility with different files of types MKV, MP4, AVI and OGG. It is very possible that you'll receive a file in the future that is unplayable with other decoders. Haali also offers the useful choice of language (audio stream) from within the basic Win98 Media Player.

The screenshot looks alright. Ffdshow is being used for both video and audio, and the MP4 splitter is invisible because it doesn't have a property dialog. Haali splitter hasn't been installed.

Haali Media Splitter has very high compatibility with different files of types MKV, MP4, AVI and OGG. It is very possible that you'll receive a file in the future that is unplayable with other decoders. Haali also offers the useful choice of language (audio stream) from within the basic Win98 Media Player.

Thanks very much for your understandable help on this.

I had the EXACT same problem. I solved it by downloading and installing the KLITE CODEC PACK 3.4.5

If you don't want to use the bloated ffdshow, then download this version ffdshow_beta5_rev2033_20080705_clsid.exe and extract the 3 files and copy them to where you want them on your system. After that, register FFDSHOW.AX 1.0.5.2032. Now you will be Golden. I hate bloated software.

FFDSHOW.AX 1.0.5.2032

LIBAVCODEC.DLL

LIBMPLAYER.DLL