Quite recently I went through the tedious process of researching the whole stand-alone player topic. Overall, there seems to be huge confusion over the actual technical features of these players and you have to scavenge dozens of Internet Forums for bits and pieces of unreliable information to aid your buying decision. Furthermore, Europeans suffer from a huge selection of players while people in the US have to choose between only a few available models.
Either way it is difficult to make an informed decision since there is no central review website for MPEG-4 players and reviews often forget to cover important technical details. Thus I decided to put together the things I learned while doing my investigations. I would very much welcome all input you can give me to this thread and in time it might become a fairly comprehensive overview.
I myself ended up choosing the Sigmatek XM-400 Pro with the Pioneer DV-575 and Pioneer DV-470 on a close second place on my ranking list. For the US market, the Oppo Digital looks like an excellent choice. From all the information I have gathered so far, all three of the above can be highly recommended.
In the following I will try to summarize some of the most important factors you should take into account when making your choice. This article will be mainly concerned with technical issues - after all, this is the Doom9 Forum. Issues like "is this player stylish enough for my living room and is it available in a colour that matches my Monet on the wall" you will have to solve yourself. 
Additionally, a strong focus will be on subtitles since almost all reviews of stand-alone players forget to accurately cover subtitle issues. Unless you live in one of the few countries where all movies are dubbed or you fancy only the bland, watered-down fare that Hollywood puts out for mentally challenged audiences these days, you will agree with me that subtitle support is important.
How to choose a stand-alone MPEG-4/DVD Player
(or at least the way I approached the problem 
)
1. Consider the alternatives:
2. Filter the broad selection of players on the market by defining your must-have features:
Go to http://divx-compare.com/section-1-lecteur-dvd-divx.htm and reduce the choice of players by searching for some rare features that you absolutely need and cannot do without. This could be stuff like .idx/.sub support, .ogm support or Nero Digital support. (Yes, the divx-compare website is in French only but it is really easy to use even if you don't understand a word of French. The 100+ players reviewed there are taken from and centered on the European market so US readers will have to stick to the global players whose products are available worldwide.)
3. Compare details, look for professional reviews & user opinions, find a firmware support community, check for availability.
Make sure you like the detailed test results for the player. Reviews help to find out if the player is very noisy or if the DVD drive breaks easily. Make sure to buy a model that has strong firmware support with people actively modding the firmware. Lastly, make sure you can actually get that model in your own country.
4. Try taking a close look at the player in a store (Optional)
If you are extremely lucky, you might be able to find the model you are looking for on display in a store. That way you can check it out real close and there won't be any nasty surprises after buying it. Before you go to the store, be sure to bring some DivX/XviD Test material along:
This is the basic process that I followed and I quickly ended up with a very small and manageable selection of players to choose from. Of course you could also start your search by determining the price range you are prepared to pay but I opted for a feature-centric approach instead.
Now on to all the juicy details on what you should pay attention to when buying a player... the following is knowledge gathered from a multitude of forums and I hope it can give you a good initial overview of the situation.
What you need to know before buying a MPEG-4 Player
1. General Hardware Criteria
Inside all of the players you will find the following:
There are several different Chipsets available on the market right now but arguably the most capable one is the Mediatek 1389 Series. Therefore I will only discuss the Mediatek.
There are several different versions of the Mediatek chip. Each one has a slightly different set of features but the feature matrix is confidential and has never been released by Mediatek. Here are some common ones:
It is important to distinguish between DivX and XviD here. DivX with GMC uses 1 warp point and is supported on all Mediatek-based players. XviD on the other hand uses 3 warp-point GMC and is not supported on any stand-alone player right now. XviD + GMC however is very very rare. No need to worry.
Unless Mediatek releases some more specs on the function calls in their firmware I doubt this will be implemented anytime soon. If you haven't heard about Matroska before, no need to worry about it.
Same as above... In fact, this also goes for any super-rare, ultra-proprietary, non-MPEG-4 codecs and containers you can pull out of your hat and that I haven't even heard about!
The upper bitrate limit also probably lies at ~5,000Mbps although that can vary from player to player. In plain terms this means: No playback of encodings of HD (High Definition) material. This is pretty much a non-issue at the moment since there is hardly any HD content available on the market for you to consume. In order to be prepared for the future, you might want to look at the first HD-capable chip on the market, the Sigma, covered extensively in this thread: http://forum.doom9.org/showthread.php?s=&threadid=84003. Personally, I'd rather wait until BluRay and/or HD-DVD have established themselves on the DVD side of things and H.264 playback becomes possible on the compressed-video side of things. I wouldn't be surprised if this takes quite a while so I consider HD support to be a moot point right now.
Right now, nada.
In the future: Both H.264 and WMV9 will be playable with the new Sigma EM8622L and EM8624L chipset, as this press release claims: http://www.sigmadesigns.com/news/pr...ases/050418.htmCome christmas time, we might already have the first H.264 compatible DVD-player!
For music, note that OGG Vorbis and WMA are supported by a lot of players as detailed below. In general however, you will be better off if you simply regard your MPEG-4 player as a movie player, and not as an all-in-one solution for any media.
3. DivX/XviD Compatibility and more
All Mediateks (except the 1389GE) support both DivX and XviD in all combinations and variations. This includes CBR & VBR MP3 and AC3 sound, even as multiple audio tracks (so-called BivX). This also includes GMC & QPel for DivX and QPel for XviD. It also usually includes .srt and .sub textfile support for subtitles.
Where the differences between players start to show are:
- .sub / .idx vobsub support: Only a handful of players on the market support bitmap subtitles at all. For me, this immediately limited the choice of players very drastically since I could not live without vobsubs (text subs like .srt very frequently suffer from poor spelling due to the OCR process performed to extract the text out of the original bitmap subtitles).
The only players that have been confirmed to support vobsubs and that I have found out about are: Pioneer DV-380, DV-470, DV-575, DV-585, DV-676A; Philips 720SA; United 4969 Divx Certified; Sigmatek XM-400 Pro; Techwood DVX-5050S, DVX-550S; Keyplug KP-5610; H&B DX-3255; LG DK-8321N, DF-8900P; Targa DP-5100x; Silvercrest KH6507; Yamaha 550; Zensonic Z330; BlueSens 3005; Medion MD 7457; RJ Tech RJ-800DVXII.
- .ogm & .ogg support: A few players support playing .ogg music files but only a very small selection actually support the .ogm container. The ones I know about are: Pioneer DV-470, DV-575, DV-585; Sigmatek XM-400 Pro; H&B DX-3255.
The latest hacked Pioneer firmware fully supports .ogm with multiple audio streams and subtitle streams. Same for the Sigmatek, except it does not support subs included in the .ogm, only external subs. I haven't checked up on the H&B firmware.
- XviD with Packed Bitstream (N-VOP) and more than one consecutive B-VOP (DivX with PB is no problem at all): Most Mediatek-based players do not properly supports this. Note that apparently players based on the old ESS Vibratto chips had no problems with packed bitstream XviD but since the Mediatek chip is superior in pretty much all other aspects I would not recommend ESS-based players. The problem occurs only if the XviD in question has more than one B-VOP at a time (one B-VOP seems to work fine) and usually leads to video stuttering (dropped frames) and loss of audio sync. This problem is actively being solved in many firmware releases right now. My Sigmatek XM-400 Pro, with the current official firmware, can handle any packed bitstream XviD thrown at it. Packed bitstream support also seems to have been implemented on the Targa DP-5100x, RJ-800DVX and LG 8900P as this article points out: http://www.divxtest.com/article.php3?id_article=93. This might mean that in the future firmware hackers will be able to implement N-VOP support in other Mediatek-based players as well. In the meantime, if your player does not support N-VOPs, the solution is quite simple yet bothersome: Get MPEG4 Modifier from http://www.moitah.net/. This simple tool can check if your XviD uses packed bitstream and disable it without having to re-encode the whole movie. MPEG4 Modifier runs with .NET on Windows or with Mono on Linux and MacOS as the command-line version (I have used it successfully on all three OSes).
- Region Free support: Unless you have been living under a rock for the past couple of years you should know about this one. Most players have some kind of trick or hack to set them region free. Before buying, be sure to look up your model in the VideoHelp Database: http://www.videohelp.com/dvdplayers.
Certain models can require expensive hardware & knowledge to be made region-free in which case you might want to look for a different player or for a dealer who sells your model as region-free.
Note that none of the current players support DivX6 Menus and Chapters yet. However, now that the DivX6 standard has been finalized, there is a chance that some of them will support it in a future firmware release... Which brings us to a very crucial point:
- Firmware update support: This is one of the most-important aspects when choosing a player. Make sure the manufacturer and/or the user community actively support your model and release new firmware versions adding features and fixing bugs. If you are from a country that uses an alphabet that cannot be displayed with the standard set of latin letters, pay extraordinary attention - all Mediateks have problems with foreign .srt charsets and codepages, so you will need a modified firmware to have .srt subs in your native language.
A good starting point for firmware mods is the Mtz Website and Forums: http://mtz.softpedia.com. Additionally, you should perform an extensive google search on your model, sometimes you can come up with active firmware developer communities where you never would have expected them - I have seen some in France, Poland and Brazil. Unless there are hackers out there modding the firmware for your model, you won't have much chance to remain up-to-date in the future.
- Nero Digital Support: I do not cover Nero Digital at all in this guide since it has already been completely and perfectly covered in this thread: http://forum.doom9.org/showthread.php?t=94538. Basically Nero Digital certified players allow you to play back any files using the .mp4 container and AAC audio. (Many thx to bond for the info)
- WMA & WMV Support: A lot of players already support WMA and WMV3. If so, it is usually always mentioned in the player specs and not difficult to find out about.
As for WMV9, right now only players based on the Sigma EM8620L chip can play those. You can find some info on it here:http://forum.doom9.org/showthread.php?t=84003
http://forum.doom9.org/showthread.php?t=87751
One such player is the Zensonic Z500:http://www.z500series.com/specs.php
(Interestingly, they also claim that they will have support for Matroska but have not implemented it yet...)
- 3ivX Support: Not many test results are available but since 3ivx is MPEG-4 compliant, an MPEG-4 player should in theory be able to play it back. Custom 3ivX extensions like Chapters will most likely not work. For 3ivx files with an mp4 container and aac audio, you will need a Nero Digital certified player in order to play them (thx to bond for the info). If anyone has some 3ivx test results to share, please post below.
- Dual Layer DVD Support: Support for dual-layer media is not always guaranteed so make sure to check/ask for it.
- Misc stuff: If you really need it, you will know to look for it. Examples include progressive scan support and the various advanced A/V connections you may or may not need like VGA or Optical.
4. Problems you should be prepared to run into
-> Probably the XviD has packed bitstream and your player doesn't support it. See Section 3.3.
Another possible reason could be bad interleaving in the file. Cyberace describes this easy way to fix that:
-> You've hit one of those really rare XviDs with GMC enabled. You will need to re-encode the movie.
-> Some of the Mediatek chips with some of the firmware versions seem to have this problem... You will have to investigate possible solutions for your model on your own, sorry.
-> This is due to overscan which can be a serious problem... Read more about it here: http://www.mastersofcinema.org/revi...okingbeyond.htm . The only real way to solve this would be to have a progressive zoom function for movies so that you can zoom out just enough until the full picture frame is visible and underscanned. Divxtest.com always tests for this functionality in their player reviews but so far no player supports it - you can only zoom out to 50% and watch the movie in a tiny window. Note that overscan does not occur if you use the TV-out on your PC to play movies so that can always serve as an alternative in extreme cases. Reportedly the Asian models Yamakawa 365 and 375 based on the Sigma chipset support progressive zoom so you could check those out if this is important for you.
-> These are default problems on all Mediateks that are easily fixed with a small firmware hack. This should not be a problem on players with good firmware update support.
-> This is basically the same for almost all the MPEG-4 stand-alones. Get a DVD/MPEG-4 player for the one function it is really intended to do: play movies. Consider getting something else for your slideshows and MP3s. A few of these things can be fixed in the firmware but don't expect too much.
5. Links you should check out (apart from this excellent forum
) In French only but quite easy to browse (otherwise try translating it with babelfish). Great source for detailed technical reviews of the MPEG-4 playback capabilites of over 100 different players.
These guys have developed an excellent Test-CD with short movie clips to systematically test for a huge and very complete set of differently encoded movies you might want to play on your stand-alone. They have also tested a good deal of players with their CD, the results can be found here: http://www.divxtest.com/results.php3. Be aware that the tests were made quite a while ago with older firmware so the situation has changed since then for some of the models listed there.
Simply the largest index of DVD players out there. Very useful to read some user reviews of the model you are planning to buy and to check if there is an easy hack to make your player region-free. Unlike the two websites above, it lacks detailed information on DivX/XviD compatibility. E.g. it does have a field called "DivXSubs support" yet is not very meaningful since it does not tell you which subtitle formats are supported in which languages.
CruNcher's excellent thread on all things Mediatek1389 on this forum. Beware though, it is 20 pages long
The DivX DVD Players subforum on the official Divx.com forum.
Good forum for information on stand-alones.
A starting point to look for both original and modified versions of firmware for your player. For models not listed there, try asking on their forum.
Mailing list discussing the Mediatek 1389 chipsets and firmware modifications.
Good Australian Forum on MPEG-4 stand-alones.
Very small new UK forum discussing MPEG-4 players.
Mostly Kiss player discussion but there are subforums for other MPEG-4 players, too.
Excellent short explanations of terms like GMC, QPel etc. used in this article, courtesy of SeeMoreDigital. Hope that information was able to help some of you!
Please feel free to post any additional information about the special features of the player you bought, new product developments or things I forgot to cover and I will try to update this Guide accordingly.
Yours Truly,
Y.T.