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Overview

• Brief introduction to DivX
• So what about the Audio?
• Improving quality and subtitle support
• Required tools and codecs
• Software for playback: Players
• Installing it all

Brief Introduction to DivX

In the past I already wrote a small introduction to DivX. In those days, DivX 3.11 ;-) was the codec to use.
The 3.11 codec was in fact a hacked MPEG4 codec from Microsoft. You can read the old article here.

Things have changed quite a bit. DivX evolved to the standard for compressed video on the Internet. It's what MP3 is for Audio.

A group of people decided to get the old codec (the illegaly hacked MPEG4 codec by Microsoft) into the legal environment. Naturally, they could not use the hacked codec, as this is owned by Microsoft. So they created a new DivX codec from scratch.

At a certain point, the group split in two: DivX.com (DivX Networks) which made the DivX codec a commercial product, and Project Mayo which is building an Open Source DivX codec (free). An Open source spin-off being the XviD codec.

Currently, I'd like to recommend the DivX.com codec, as the Open Source codecs seem to have some minor issues you will not find in the commercial DivX codec by DivX.com.

Note: if you use the codec for playback only, then DivX.com offers you a free codec.

So what is the DivX codec?

DivX is a codec, much like the MP3 codec for Audio. It allows efficient high quality video compression suitable for system playback (files and player on your PC) and streaming playback (files on some server on the Internet and the player on your PC, playing the movie while downloading the movie data). Commonly DivX is used for system playback.

Note: A CODEC is little piece of software for COmpression/DECompression and is used for example for Audio and Video.

DivX basically supports any resolution for compression and playback, so a DivX movie can be played on a PC, a game console (ie. PlayStation 2, Game Cube and the X-Box can playback DivX after modifying the firmware a bit), some standalone DVD/DivX players (for example the KiSS DP450/500 or the Liteon LVD2001), an Apple Macintosh or even a PDA (for example the iPaq).

The DivX quality can be compared with DVD quality, however, the space required to store such a movie is significantly lower than with a DVD movie. Usually, a good quality movie will fit on a single CD instead of a DVD. For comparison: a DVD formatted movie commonly takes about 7 Gb of space, a similar DivX movie less than 1 Gb!

This advantage is not only nice for those who burn the movies to a CD or DVD. It's also a great improvement when downloading a movie. Imagine the time needed for downloading 7 Gb of data ... If you want to know about where to download DivX movies, then please read out article on "Where to download".

Note: The name "DivX" was based on an not so succesfull DVD protection mechanism called ... DivX. This protection mechanism failed to become accepted and died a silent dead.

When we say "DivX," we are not referring to the Digital Video Express (DIVX/DVE) service previously marketed by Circuit City. If you need information about Circuit City's DIVX, you might try the DIVX Owners' Association.

So what about the audio?

Well, DivX does not specify the format for the audio track for the movie.

In the past, WMA (a Microsoft audio compression codec) was used for compressing audio. However, the quality of this codec was really bad. Not only that: the compression was not that good either. So please: forget about this format!

After a while MP3 became the default format for the audio track. This made perfect sense, as MP3 was very popular and produced very efficient (high compression) and good quality audio. For more information on MP3, read our "What is MP3" article.
MP3 is still the most used audio codec for DivX movies!

Developments didn't stop there ...
A new Audio compression format called Ogg Vorbis surfaced. Ogg Vorbis had some cool features like better compression and higher quality. But that wasn't the main thing. Ogg Vorbis is FREE. Not only in pricing but also free of any copyright/patent issues.
So some guys decided to use Ogg Vorbis as the audio codec for their DivX movies, and I have to admit: quality is excellent.

This development didn't stop real audio freaks to use the AC3 encoding thechnique (by Dolby Laboratories) as an audio track.
AC3 allows us to keep the original soundtrack of the DVD (as these are usually encodec in AC3 aswell). AC3 gives us the possibility to use 5 audio channels is super quality. AC3 Filter is one of those (very good!) free AC3 decoders.

So, now we have 4 codecs for audio: WMA, MP3, Ogg Vorbis and AC3.

One would say that this should be enough,... but it wasn't for some folks.
What do we miss when using either of these formats? Well, we miss the support to include multiple audio tracks in the DivX/AVI file. Multiple audio tracks (as seen with DVD's) allows us to switch language or listen comments on the movie.
I'm not using this feature, but I can imagine that some folks like it ...

In order to support multiple audiotracks we do need a so called "Stream splitter" which allows us to select an audio track we wish to hear. This kind of switcher is not really a codec. It's more like a work around for the limitations of the AVI format which natively supports only one audio track.

Improving quality and subtitle support

A prefect world would be nice,... but unfortunally, the world isn't perfect.

When playing DivX movies we can encounter some weird problems. Usually, these problems are codec related. For example:

The XviD codec creates an DivX formatted movie. However, when doing playback with another DivX codec, the screen can be flipped (ie. everything upside down), show green articfacts (green screen, green blocks) or show a "melting" behaviour.

So we either need to use the proper codec for playback or need to fix it otherwise. Finding the exact codec used for compressing the movie is not very easy to do, and you might need to repeat it for the next movie, which (naturally) uses a slightly different version. Not an option I would say.

A better solution is FFDShow (Alfa version!). FFDShow is a great little tool (actually: a DirectShow filter) that "fixes" these problems on the fly, without the need to install that specific codec.

FFDShow comes with an additional great feature: Subtitle support!

When a mvoie starts playback, FFDShow will look for a file with the same name as the movie. For example: MyMovie.AVI can have the subtitles: MyMovie.SUB, MyMovie.SRT, MyMovie.RAR (holding multiple subtitle files!) or MyMovie.SMI.

When it finds such a file, it will allow you have them displayed with the movie.

Video is not the only "problem" we might encounter. Some folks tend to record audio very soft, ie. you need to crank up your amplifier to hear something. There is a software solution to this problem: TFM Audio Filter.

Note: TFM Audio Filter and Morgan Stream Switcher cannot be installed together as they are incompatible!

What codecs/TOOLS do we need then?

Well, if you're creating the DivX movies yourself then you already know which codecs to use. But when you didn't create the DivX movie yourself,... well that's a different ballgame alltogether.

In genral we can use two approaches for both Audio and Video codecs:

1. Just install all possible codecs.
It definitly can save you some headaches. Several so called codec-packs help you with that.

2. Analyze the DivX movie and install the requered codec manually.
Not really the way to go, but sometimes needed when you forgot a codec.
Read our GSpot article on how to identify the required codecs. This can be usefull when playback of a DivX movie isn't really working (usually the problems are Audio related).

We go for the first option and keep the second option in mind when a movie doesn't playback right.

This is our (WeetHet) highly recommended set of codecs and filters

Note: you do not need to download the individual packages - you can download the full package from the WeetHet download page, Morgan Stream Switcher not included:

Be aware that there are much more advanced packages out there! These packages conatin much more codecs, filters and tools. The downside: they are more complex to comprehend as well ... so we stick to the basics here. An example: the ACE Mega codec pack and

Software for Playback

It's all nice and dandy to have all the possible tools you might need, but what about the actual player? What software do I need for playback?

Well, naturally, you will need the codecs and filters we just suggested.

Besides that we need some kind of front-end to access all this. We need a "player" - an application capable of doing DivX playback.

One player is already installed on your Windows PC: The Windows Media Player (WMP).
Downside is that this player always tries to "download" codecs from the web - not to mention that we are not sure what information the WMP is sending to big brother Microsoft. It also limits the access to the controls of some of the most important DirectShow filters.

Another player that might be on your PC can help us as well. PowerDVD (as of release 4) and WinDVD (as of release 5) manage to playback DivX as well. However, they too suffer from the same limitation on access to the controls of some of the DirectShow filters. However, compared to the Windows Media Player, they are much better.

Finally, there are some free DivX players on the web as well.

One is the one that comes with the DivX codec. It works and that's about it. I do not recommend using it as again the DirectShow controls cannot be accessed.

Another one is BSPlayer. This puppy is very small and efficient.