DIVX

This is a guide on how to configure your system to best support the ever growing number of Media file formats and compression types. The guide is based around playback using Zoom Player and requires several free and commercial components for maximum performance. This guide assumes you are installing on a clean system. If you are not, you may want to uninstall any and all "codec-packs" you previously installed and may want to carefully read the Merit section.


Part 1 - DIVX 3.11:
DIVX 3.11 is actually a hack of the Microsoft MPEG4 encoder/decoder. It was cr 16516i81q eated due to microsoft artificially limiting their code to not work properly in the open-ended AVI wrapper (At the time microsoft wanted to limit it's use to the ASF format, now known as Windows Media Video).

The only reason you should really have for installing DIVX 3.11 is if you are using Windows XP. As part of the DIVX 3.11 installer, it also installs an MP3 Encoder/Decoder that replaces the crippled one microsoft ships with Windows XP, the DIVX 3.11 install in itself is pretty harmless and shouldn't cause conflicts.


Part 2 - DIVX 5.xx:
DIVX 4.xx and DIVX 5.xx were a complete rewrite of the MPEG4 simple profile and advanced simple profile encoder/decoder. This is a legitimate product and not a hack. This codec can decode DIVX 3.11 content and it actually overrides the DIVX 3.11 decoder once installed. This behavior can be changed by altering it's decoder merit (see Merit section later on).


Part 3 - FFDShow:
FFDShow is an MPEG4 Decoder filter with lots of Post Processing features. It allows you to decode DIVX (3.11/4.xx/5.xx), XVID and Microsoft MPEG4. It also acts as a VERY strong post-processing filter than can word on the mentioned formats and on RAW video (as decoded by DVD Decoders). It can exchange your image, it can DeInterlace video and it's only getting more powerful with each version. It is currently the most highly recommended filter for use with DIVX/XVID playback and for you expert users, it can be used to improve DVD playback. Of course, to use some of it's more exotic features, a strong CPU is required.

FFDShow is very "Conflict Friendly". You can tell it which formats you want it to play and it overrides any previous decoders assigned to that format, all very cleanly.

Part 4 - OGG/OGM:
Similar to AVI, OGG is container format. It can contain any number of streams, including audio, video, chaptering, subtitles, etc... OGM is the extension given to OGG containers that include an Audio/Video Stream (OGG Movie).

To Playback OGG Audio and OGM Video files, you need the OGM DirectShow filter.

Part 5 - AC3:
To play back AC3 (Dolby Digital) within AVI files you have two options.
1. Use a transport filter that relays the AC3 data from the AVI container into the Decoder and the second is the decoder itself.
2. Use The Open-Source AC3 Decoding filter (which contains both the Transport and Decoder in one filter).

My personal favorite AC3 Decoder filter is that one that comes with the WinDVD player or decoder pack. This player is commercial and can be bought at InterVideo.


Part 6 - SVCD / VOB / MPEG2:
Due to licenses involved, MPEG2 decoding is pretty limited to commercial software. Any freeware decoder you may encounter is pretty much illegal. On my own system, I use the WinDVD Audio/Video Decoders, but you may also use the Cyberlink filters, Elecard filters or any other valid MPEG2 decoding filters.

Unlike MPEG4, MPEG2 decoding can be VERY problematic. For starters some filters force an aspect ratio on the player which prevents proper playback. To bypass this issue in Zoom Player, go to the Options dialog, switch to the Manual Filter section and enable "Force Overlay Mixer". This may also give you smoother playback under some conditions.

The second problem is filter conflicts. For example, by installing the Elecard filters, they also latch themselves into decoding MPEG1 content and even hook up into playing MP3 audio on AVI files. This can cause Audio Desync, slower seeking in MPEG1 files and other nasty surprises. This is why I like the WinDVD filters, they don't cause these conflicts.

There is an issue with some MPEG2 files where you try to play the file and the duration appears as 0 seconds and you can't seek. You can fix this issue for 95% of the videos by doing the following fix:
Run Zoom Player, Open the Options dialog, switch to the Manual Filters section and click on the "Registered Filter Manager" button. You will be presented with a list of filters currently registered on your system. Find the one called "MPEG-2 Demultiplexer", change it's merit to "00200000". Next find a filter called "MPEG-2 Splitter", change it's merit to "06000000". Now restart Zoom Player and most videos should now show their proper duration.

On very rare occasions instead of seeing the real video duration, you would see something like 4 seconds, this is a really badly encoded MPEG2 file. The only decoder I know that is able to handle these files is the Elecard decoder, and with these installed it's rather a headache getting it to work well without effecting other system components.

Lastly, when playing back burnt SVCD discs, you must install the XCD File-Source filter. Without it trying to open an SVCD file would make the system scan the ENTIRE file (which can take several minutes) before returning with an error saying the file is can not be played. It is important to remember when installing the XCD filter that you must use its installer, manually registering the filter will not work properly as the installer enters a few important registry entries.

Part 7 - Subtitles:
The best Subtitle Renderer is a DirectShow filter called DirectVobSub (Part of the VobSub package). Once installed, playing a movie with external subtitles (every format) is possible. Pressing ALT+"S" with a video loaded should open up the DirectVobSub subtitle interface.

The Merit System:
Media Playback under any DirectShow player (such as Zoom Player) is based on the Merit System. Each filter has a function, it can be a reader, parser, decoder or renderer. A reader filter understands the basic file structure and knows how to read it. A parser filter will use this structure to split the file into streams (audio/video/subtitles/etc...), the decoder filter decodes a stream and sends it to a renderer filter which displays the data (or sounds it in the case of audio renderers).

Now what if you have two filters that both fit the same job profile? Here's where the merit comes into play... The filter with the highest merit point gets chosen for the job. This is a bit more complex than it may seem. As consider this situation, you can have one filter that decodes more than one format. The same filter can be used to decode AC3 audio and MP3 audio. You can have a second filter which only decodes MP3 audio. You want the filter that only plays the MP3 audio to be used for MP3 playback, but still use the other filter to play back AC3 audio. You do this by assigning the MP3 only decoder a higher merit.

There are several merit usage classes (these numbers are in hex):
80000 - Preferred
60000 - Normal
40000 - Unlikely
20000 - Do not use
10000 - Software Compressor
10050 - Hardware Compressor

You should stay clear of the compressor classes, but basically, you can see where this is going. You can use any number above the class while still maintaining within the class, for example a merit of "400005" is still "Unlikely". By rearranging the merits of filters you can eventually resolve most conflicts. However, if conflicts still occur, you can try unregistering the filter entirely and assuring the system would never be aware of it.

To change a filter's merit, see details in Part 6.


Final Words:
Make sure you have the Force Overlay Mixer checkbox enabled in Zoom Player, without it under Windows XP, the VMR renderer is used and can conflict with certain media playback (makes it choppy or desynced). Don't be tempted for the quick fix, installing codec packs can cause multiple issues, so make sure you know what gets installed.

There is a filter called "mmswitch". This filter is used to provide old media players with the ability to play AVI files with multiple audio tracks. It is not required when Zoom Player is used and can actually cause instability and other odd behavior. Make sure you unregister it (easily done on the Manual Filters options dialog).

If you had the "smart" idea of unregistering every single filter within the Registered Filter Manager and suddenly found that no media playback works anymore, here's how to fix it:
Open the Windows "Run" dialog and type "REGSVR32.EXE quartz.dll". Then search for every file with the ".AX" extension within the Windows System directory and run "REGSVR32.EXE filename.ax" where you replace the "filename" with the actual file name.

If you have any other questions, refer them to the Zoom Player section of the forum