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Please, please do not encode to ASF unless you are absolutely sure of what you are getting into. Microsoft claims it is illegal to decode ASF outside of their drivers and does not allow transcoding compressed MPEG-4 to other formats with the Windows Media Format SDK, making it nearly impossible to do so legally. Before transcoding to ASF, make sure you understand that it will be difficult for anyone to decompress your file, even just to MPEG-1 for better viewing performance. By using ASF, you are trapping your content in a less open format and restricting who can view it, even within the Windows platform. You can encode video files in MPEG-4 V2 with comparable quality and you will still be able to distribute in the open, unrestricted AVI file format.
Avery Lee, Virtualdub programmer
Consider the state of multimedia today. Fueled by the rapid increases in storage and processing power, a vast array of technologies has appeared. Some are fully open standards. Some are proprietary. Some, such as the always popular MP3, are somewhere in between. Some of this technology is becoming obsolete. The AVI format been patched so many times it has problems with files over 1, 2 or 4 gig and cannot reliably handle VBR audio. MP3s acoustic model has been superceded by formats that sound better at any bitrate. As these technologies are replaced, a hole in the market opens. This hole is becoming the cause of one of the biggest fights in computing history.
Once again we see the conflicting ideologies of open source and proprietary formats. The open source movement's new solutions include the vorbis audio codec, OGG and OGM containers, and the xvid video codec. The proprietary solutions, primarily from Microsoft, include the Windows Media codecs and the WMA/WMV/ASF container (singular - the formats are identical :-)). The two sides are fighting a battle which will decide the future of computers. Free software is playing its traditional strengths of price, rapid development and freedom from restrictive licenses. Microsoft and the other proprietary formats (realaudio and sony) are as usual fighting dirty, primarily by bundling windows media player.
I cannot stress the importance of this stage. If open source wins, future multimedia will be cheap, portable and DRM-free. If Microsoft succeeds in bundling its way to the top future multimedia will be restricted, DRMed, non-portable and very expensive. In addition some proprietary media formats, especially Microsoft's, are designed to be very difficult to convert to open formats. Just to annoy Microsoft, heres my guide to converting ASF, WMA and WMV files to AVI.
Most popular multimedia technology today is somewhere between these two extremes. For example, the MP3 format is an open standard in that anyone is free to study the format. However pieces of MP3 compression are patented. Initially the patent owners, a German company called Fraunhofer IIS, allowed anyone to use MP3 freely. This is how MP3 became the dominant format for music on the internet, both legal and illegal. Until September 98, when Fraunhofer sent its infamous letter of infringement, demanding royalties for all encoders, commercial players and even music sold in MP3 format. In the resulting royalty chaos most free encoders shut down, including Plugger, CDEX, soloH, 8Hz, Blade and Canna.
This cannot be allowed to happen again. Study the Windows Media developers licence, which suggests someone in Microsoft really hates open source. If you want to write a program using WM formats, not only must you keep the source secret but you must not let others redistribute the software, or even distribute it along with other open source software!.
Take a look at these sections from the Microsoft ASF license. This are only the requirements for the ASF container, additional restrictions are needed to decode the WM codecs.
My emphasis
1a) Specification. Provided you comply with all terms and conditions of this Agreement, including without limitation Section 2 below, Microsoft grants you the following limited, non-exclusive, world-wide, royalty-free, non-assignable, nontransferable, non-sublicenseable license during the Term (defined below), under any copyrights owned or licensable by Microsoft without payment of consideration to unaffiliated third parties, to: (i) reproduce and internally use a reasonable number of copies of the Specification in its entirety as a reference for the sole purpose of implementing ASF in your application or utilities (your ?Solution?); and (ii) reproduce and have reproduced in object code form only your implementation of ASF made pursuant to the terms of this Agreement (the ?Implementation?), and distribute, directly and indirectly, the Implementation(s) (only in object code form) solely as part of and for use with your Solution.
2(e) Your Solution may not save to permanent storage, transfer to another process, write to a network, or otherwise export, content compressed with Windows Media Codecs unless such content is contained within ASF.
2(g) For a variety of reasons, including without limitation, because you do not have the right to sublicense the Necessary Claims, your license rights to the Specification are conditioned upon your (a) not distributing the Implementation in conjunction with Identified Software (as defined below); (b) not using Identified Software (e.g. tools) to develop the Implementation; and (c) not distributing the Implementation under license terms which would make the Implementation Identified Software. "Identified Software" means software which is licensed pursuant to terms that directly or indirectly: (i) create, or purport to create, obligations for Microsoft with respect to the intellectual property in the Specification (including without limitation, any Necessary Claims) licensed to you pursuant to Section 1 (!Microsoft IP!) or (ii) grant, or purport to grant, to any third party any rights or immunities under Microsoft IP. Identified Software includes, without limitation, any software that requires as a condition of use, modification and/or distribution of such software that other software distributed with such software (x) be disclosed or distributed in source code form; (y) be licensed for the purpose of making derivative works; or (z) be redistributable at no charge.
Section 2(g) is not unique to ASF. It is a common clause in many Microsoft licenses, including most of .NET. A demonstration that Microsoft's hatred of open source goes far beyond simply hating competition. Microsoft hates open source in a way far more personal than simply money. Look at the license. Its not just saying programmers using the ASF format can't release source, its saying they can't even use an open source text editor to write the programs or use an open source compiler. The program cant even be distributed on a magazine coverdisc if theres an open source program on it as well. Its a sort of corporate vendetta, a fight between the the ideology of open source and the insatable thirst for money and control of Microsoft. The very nature of proprietary technologies makes it impossible to release programs using them under a conventional open-source license, as this would require licensing the right to use the technology to everyone attempting to modify the source. For example, the popular Virtualdub software was threatened because it was able to read ASF files, even through that support was added only by studying ASF files, not by studying the official spec from Microsoft. Comments from Virtualdub programmer here. This was largely because Microsoft really dislikes anyone attempting to convert their proprietary formats to something that can be played outside windows - see the section in the license quoted above?
Responding to this threat, I am now going to list some of the fully open media technology and its advantages. I strongly encourage people to support these formats. Remember there are no licenses to consider and no royalties to pay if you wish to use these technologies.
Vorbis audio codec and OGG container. The vorbis audio codec, usually used with the ogg container in an "ogg vorbis" file, is generially accepted to be one of the best performing codecs available. It performs far better than MP3 at any bitrate, and can outperform WMA or ATRAC3 when used properly. The only disadvantage is that it is not suitable for using in AVI files (Putting a VBR stream in an AVI is very unreliable), so video with a vorbis compressed soundtrack must be stored in OGM containers.
OGM container. This audio/video container was designed as a replacement for the AVI format. It has many abilities AVI lacks, such as support for subtitles and multiable audio streams, makeing it popular with anime fans. Its main advantage through is its ability to use VBR audio streams (AVI cannot) and its far better AV sync than AVI. Unlike AVI, OGM will very rarel lose sync. No more sound slowly slipping ahead or behind the video. The format is a modified version of the Ogg audio container.
Spexx. An audio codec optimised for low-bitrate speech, for IP phones.
Flac. A lossless audio codec, used mostly for archival recordings.
Xvid, a divx-like (and based on divx) MPEG4 video codec. Xvid was founded by people who didn't like the overly-commercial divx project. xvid is free software of course. Xvid provides a few geeky options that divx doesn't, used correctly it can be higher quality at the same bitrate, but isn't as fully devloped as divx and lacks a few of its features.
Recently, I have started work on a new section. There are many sites containing databases of ed2k-links. I am making another. Mine, however, contains only public-domain or distribution-permitted media files in the above formats.