| Answer |
· What is XviD?
XviD is an ISO MPEG-4 compliant video codec. It's no product, it's an open source project which is developed and maintained by lots of people from all over the world. Top
|
· Why should I use XviD?
Well, you don't need to at all. We the developers of XviD are just ordinary people, who happen to enjoy writing code for video compression, so we have no disadvantages (financial or any other) if you choose something else than XviD...
However there are good reasons why you could like to use XviD: We believe that XviD is the best currently available MPEG-4 video codec solution and additionally XviD is free software!
Top
|
· How do I encode using XviD?
There are lot of good advises available for win32 users there:
http://www.doom9.org/xvid.htm
http://www.doom9.org/gknot-main4.htm
Unix users can have a look at mencoder/transcode documentations/forums/mailing lists. Top
|
· When I use the Xvid lib in a multithreaded app to encode 2 files simultaneously (under Windows or Linux) it crashes - why?
Old versions of XviD weren't threadsafe. This issue has been fixed, so please update your copy of XviD. Top
|
· What platforms has XviD been ported to?
Core library is highly portable.
Known working platforms :
- Win32 (MSVC, cygwin, mingw)
- GNU/Linux x86/ppc/sparc/ia64
- MacOSX
- *BSD
- Solaris 8 Ultra Sparc
- BeOS Top
|
· How do I install XviD on Linux?
Follow the steps described in the doc/INSTALL file, section "The unix way". Top
|
· Can I distribute your codec along with some of my own videos on CD-ROM?
XVID is under GPL license, which means you can distribute it freely, e.g. on a CD-ROM or whatever form you like.
However, if you distribute XVID in binary form, you have to add the source code to the CD-ROM, too. Top
|
· I've obtained and unzipped the files from your download section but my XviD videos still don't play in Media Player - what's wrong?
The files from xvid.org contain source code only which is a package that's good for all operating systems and hardware platforms. Before you can actually use XviD, you have to compile the source files with an ANSI C compiler for your OS and hardware platform (like Microsoft Visual C++ for Windows or gcc for GNU/Linux and other free OSes).
If you don't know what the above shall mean at all and you just want to watch a video in Windows Media Player, then the source code package isn't right for you and you should use google to search for 'XviD binary'. Already the very first search result will provide what you're looking for. Top
|
· I have downloaded several movies in XviD format from the net and am unable to watch them - what to do?
With high probability you've downloaded some pirate movie copy. This is illegal and we're strictly against piracy here at xvid.org. Therefore we won't provide any help or support how to watch such illegal movie copies. Go to the store and buy the DVD! Top
|
· Can I encode some videos in Microsoft's MPEG-4 V1/V2 format and then watch them with XviD or vice-versa?
No, you can't. Despite the name, MS MPEG-4 is not truly standard compliant MPEG-4 - rather it's Microsoft's own proprietary randition of MPEG-4 technology and is incompatible with the international MPEG-4 standard as specified by ISO. So unfortunately, XviD and MS MPEG-4 cannot interoperate. Top
|
· I bought a hardware player that had 'XviD compatible' printed on the box but it doesn't play many of my XviD files - what's that?
This is a problem we're aware of, also see our public announcement regarding hardware devices. Up to now, we don't know of any device on the market that would be fully compliant to XviD, so would be able to play all XviD encoded content.
Therefore we cannot truly recommend buying any of such devices and because of this we also never gave permission to any hardware manufacturer so far to advertise their products as being 'XviD compliant'. Unfortunately, even though XviD's logo and name are protected by copyright and trademark law, nonetheless some manufacturers advertise their products as 'XviD compliant' without auhorization.
Therefore, before buying any of such devices you should look for information about what the devices are really capable of in order to decide whether they really suit your needs. A good starting point for further information and discussion is the 'hardware players' forum at doom9.org: http://forum.doom9.net Top
|
· Can I use Windows Media player to play Xvid files?
Yes. Top
|
· I'm watching a XviD file in Media Player and I see the video but there's no sound?
XviD is a video codec, it has absolutely nothing to do with sound. So if you see a video then XviD works just fine and we can't help you here. For sound, you'd need an appropriate audio codec, but this is an issue that can't be discussed here - go to a more general audio/video resource page like doom9 Top
|
· What are all these advanced features: B-frames, GMC, Quarter-pel, adaptative quantization? How do they work?
Explaining this in detail is not possible here. As a short answer:
MPEG-4 is very effective in compression, because it reuses data from one image to generate the next one (still images of a video are only 1/25 of a second or even less apart from each other, in almost all cases they look very similar).
There are different ways how to detect which part of the picture can be reused, and QPel = "Quarterpel Motion Compensation" and GMC = "Global Motion Compensation" are two advanced ways of doing this. Normally you only use "Halfpel Motion Compensation", so the resolution is higher with Quarterpel.
A different step in compression is to divide some coefficients by a number to gives them smaller values (and hopefully zero). This is called "Quantization". Normally, every 16x16 block in the image is divided by the same value, but with "adaptive quantization", for every block a different value can be chose.
This _can_ lead to better quality, when e.g. important parts of a picture like faces are compressed less, and less importants part (background) are compressed stronger, but it's still somewhat experimental. Top
|
· I want to burn my XviD files on DVD and play them on my DVD player - how to do that?
XviD is a MPEG-4 video codec. Regular DVD-players don't play MPEG-4, so if you want to watch XviD encoded files on a DVD player you have to convert them e.g. to VCD or SVCD first. There are many websites explaining this, go e.g. to http://www.vcdhelp.com
Alternatively you'd need a special MPEG-4 (DivX or XviD) capable DVD player that should be able to also play (some) XviD content (but be cautious with MPEG-4 hardware players - see above). Top
|
· I certainly found it amusing to note that XviD is reverse of DivX. I wonder: was that intentional?
Yes, the name XviD is DivX read backwards, but basically it's just a cool name ;-) Nonetheless the reversed name may also reflect the will to mark the ethical differences between DivX and XviD:
DivX is proprietary software, with an opaque development cycle that follows only a commercial logic. XviD is Free Software (licensed under the GNU GPL), open to third-party contributions and aims for standard's compliance, portability and interoperability, high processing speed and superior quality. Top
|
· I have problems compiling the '.asm' files: I'm getting strange errors, so what should I do?
Make sure you have nasm installed. If you have but you still have problems, make sure you have the very latest version of nasm installed. Download or upate nasm from: http://nasm.sourceforge.net Top
|
· I plan to use XviD in my own program and I'm going to modify it. Do I have to distribute my program as "open source" then?
Yes, XviD is released under the GNU GPL license which requires that all derived work from XviD also has to be distributed under the terms of the GNU GPL. A derived work, as defined in the GNU GPL, is a software that links (statically or dynamically) against XviD or includes XviD.
For more details see Section 1 and 2 of the GNU GPL license available in the source distribution or at http://www.gnu.org/licenses/gpl.html Top
|
