A: Microsoft has deprecated the MCI interface, and is promoting DirectShow as the standard media playback engine for all current and future operational systems. DirectShow is more compatible than MCI and the main DirectShow engine includes MPEG1 decoding capabilities, so you get guaranteed playback on all machines were DirectShow is installed. Windows Media Player is DirectShow-based (see technote MP011), which indicates this is really the best interface to use today for media playback on the Windows platform. Mpeg Advance Xtra also automatically works on the Macintosh platform using the Quicktime engine, so you get guaranteed playback on all platforms supported by DirectorMX with no additional system installations.
B: Most older hardware-based MPEG decoders shipped only with MCI drivers, so they are not compatible with newer technology like DirectShow and Quicktime. Using a hardware-based decoder like the RealMagic Hollywood or the CreativeLabs PC-DVD Encore DXR2 was at a time the most common method to incorporate MPEG2 content in a presentation, since software-based MPEG2 decoders required a very fast Pentium II or III machine for good results. MpegXtra was a good tool to interface with these MCI-based decoders, using older versions of Director and older operational systems. MPEG2 projects using hardware decoders were usually recommended only for limited distribution (kiosks or business presentations) were the developer has control over the hardware that will be used for the final presentation, and has tested the driver with MpegXtra. Some MPEG2 decoders are incompatible with basic MCI commands and can not be used with MpegXtra. This coupled with the inherent flaws of MCI lead to a high rate of incompatible systems, which prevented MPEG2 projects from being deployed to a wide audience safely. For current projects a hardware-based decoder is not needed, since current CPUs are fast enough to play MPEG2/4 video using software decoders.
C: Quicktime is a good option for delivery of MPEG content primarily to the Macintosh platform. A fast machine (PowerPC 604 or G3) is recommended for good playback quality. Starting with Quicktime 6 it is also possible to use Quicktime to play MPEG1 content on the Windows platform, using Director's built-in Quicktime Xtra. This solution however requires that all Windows users of your CD-ROM install the current version of Quicktime. This can be a restriction in some corporate environments, for example. For wide distribution we recommend using Mpeg Advance Xtra, since it will use the default MPEG player already present in all modern Windows systems, with no installation needed.
D: A few software-based MPEG2 and DVD decoders ship with DirectShow filters, and most can be used with Mpeg Advance Xtra. One example is MediaMatics DVDExpress software, which ships in most Compaq Presario systems. When this decoder is installed it is possible to use the Xtra to render MPEG2 files. The same is true for MPEG4 files, using a decoder like Ligos MPEG4 player. This is a good solution if the developer has access to the target machines and can confirm that the version of the decoder installed works with the Xtra. This solution is however only indicated for limited scale distribution, like kyosks or presentations done for a specific group of target machines. The reason for this is simple: some MPEG2/4 decoders on Windows do not implement all DirectShow functions required for the operation of the Xtra, and may cause problems during playback. Older versions of WinDVD and PowerDVD for example are known to operate incorrectly under WindowsXP, and may even corrupt the DirectShow subsystem in certain configurations. Technote MA007 contains more information about issues with 3rd party MPEG2 and MPEG4 decoders in DirectShow.
Mac users can play MPEG2 content using Mpeg Advance Xtra if the Quicktime MPEG2 component is installed. This is a separate (paid) component available directly from Apple.
It is important to notice that there are no freely redistributable players for MPEG2 content, and the typical cost of a decoder is around U$ 15-20/copy. This restricts MPEG2 usage to contolled situations like the ones described earlier, and coupled with the moderate level of incompatibility with 3rd party drivers, makes MPEG2 unsuitable for large scale distribution.
E: Quicktime 6 already includes MPEG4 playback. It is in fact currently the only freely redistributable MPEG4 decoder, so this makes it an attractive solution for MPEG4 delivery, using Director's buil-in Quicktime Xtra. The only drawback is that all of your Windows users will need to install Quicktime 6. More information about MPEG4 issues and recommendations can be found at technote MA008.
MPEG2 playback can be added to the Quicktime engine on both Mac and Windows with the purchase of the optional Quicktime MPEG2 component (U$ 20 per platform/copy, directly from Apple) The advantage of using Quicktime instead of a 3rd party Windows MPEG2 decoder (via Mpeg Advance Xtra) is simple: you are guaranteed to be using the same MPEG2 decoder engine on all machines, and compatibility issues are reduced. However if the target machines already have a compatible MPEG2 decoder you may still want to use Mpeg Advance Xtra (see technote MA007 for MPEG2 issues on Windows.)