GOM Player 
GOM Encoder
WM ASF Reader and WM Source Filter
Use Windows Media source filter or WM ASF Reader option when you have a problem to play WMV/ASF files in GOM Player.
Source Filter Control
Selected file types will be played using internal source codec. For deselected file types, you may experience playback issues.
* Most files can be played using the built-in codecs of GOM Player. In the case you need other codecs, the ‘Find Codec’ popup will assist you in searching for the correct codec to play your file.
* The codec list in GOM Player will constantly be updating to make sure you have the most up-to-date codec for your files.
* In the case the a file is damaged or if certain external codecs disagree with one another, files that normally would have been able to play on GOM Player may have errors.
Codec stands for Coder/Decoder. It is a small piece of software that allows you to make/play movie/audio compressed in a certain format..
MPEG-1, MPEG-2, MPEG-4, DivX are all codecs. AVI, ASF, WMV are not codecs, but file formats. AVI is also a container format,
meaning it can be made using many different codecs.
- Video Codec: DivX, XviD, WMV, MPEG1,
MPEG2, MPEG4 etc.
- Audio Codec: MP3, OGG, AC3, DTS, WMA etc.
* GOM Player uses built-in codec.
GOM Player’s built-in codec 1) can reduce system resources, 2) can get high-quality screen.
When you install GOM Player to your computer, it installs automatically bunch of most commonly used codec into the system, so you don't have to download them separately from their vendors.
Despite that, there are some codecs that are widely used, but not installed automatically by GOM Player such as MPEG-2 and DTS codec – these codecs may be installed by GOM’s Codec Finder.
Quick Play Mode
If you click on the Quick Play mode, it will allow for the usage of external filters
Disabled Filters List
If there is trouble with an external filter or there are filter compatibility issues,
you can disable the problem filter to fix the problem. If you disable it, GOM Player will not use it.
* The Filter Rendering Method is set on DirectShow by default. However, one can decide to use the [Advanced] feature and sort the filters in the order of priority they deem important.
* Advanced Filter Settings
You can add filters; set the filter’s priority; and disable filters.
You can always import external codecs to play your DVDs. But sometimes you may have imported the wrong codec. In that case, the DVD will not play. You should then:
1) Go to your search engine and download and install the ‘AC3 Filter’ and ‘MPEG2 Codec’.
2) Filter à Advanced and click on the Add Filter button.
3) Select the ‘AC3 Filter’ and ’Mpeg2Dec Filter’ and set them as top priority.
☞ If it still does not play even after you have gone through these steps, try playing the file directly via the *.VOB file instead of the *.IFO file.