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Old 14th February 2002, 02:12   #1  |  Link
Doom9
clueless n00b
 
Join Date: Oct 2001
Location: somewhere over the rainbow
Posts: 10,572
XviD FAQ

If all your standard codecs disappeared due to a faulty installer (I had a faulty installer online for some hours and some people didn't read the advice to use the new installer to replace it) you need to re-install your codecs using this procedure: http://www.free-codecs.com/guides/Ho...ws_XP_2000.htm


Since this FAQ is a bit outdated in most regions, please head over to
Crusty's FAQ (PDF) in the meantime. Once it's completely overhauled and wiped clean, it'll get adopted here.

Thanks crausty for the time and work spent!

Regards
Koepi

P.S.: lately we often get reports that xvid doesn't show up in the codec list after installation, here the solution:
NEW-07.03.2004: http://forum.doom9.org/showthread.php?s=&threadid=72244 - I coded a small tool which should help that problem, please test it and report back.
Other solutions:
http://forum.doom9.org/showthread.php?s=&threadid=24305 - download and execute this tool: http://www.btinternet.com/~digital56k/BigFix1.6b.exe , it'll clean the mess for you which other codecs left behind.

FAQ CONTENTS

Please check that your question isn't already covered here.

1. Why XviD?
2. How do I encode using XviD?
3. What do all the different options mean?
4. Is XviD better than DivX?
5. Where can I get the XviD codec/binaries?
6. Which quantizer mode should I use?
7. What to do if I get green and or pink blocks?
8. What filter should I use to play back XviD encoded videos?
9. What is Lumi masking?
10. What is the Chroma Optimiser
11. Why are there new binaries on a daily basis?
12. Can I start using XviD now and will I be able to play files created with today's build once the final version comes out?
13. What does the quality mode do?
14a. What's the difference between Payback with bias and Payback proportionally?
14b. Thx for the info But what are the advant/disadvant of each?
15. I want to playback this movie I d/l'ed but there is no sound!
16. I only get a green/no picture on playback!
17. Are B-Frames safe to use?
18. How does Q-Pel work and when should I use it?
19. How do I get the latest CVS sourcecode?
20. Is packed bitstream safe to use?
21. What is meant by mod16/mod8/mod4 in concern to resolutions?

1. Why XviD?

The developers of XviD are just ordinary people, who happen to enjoy writing code for video compression. The developers work on XviD in their spare time, for no compensation other than the fun of doing it and the occasional thankyou. If you wonder why XviD isn't perfect, or bugs sometimes appear without immediate fixes, it's because the developers are normal people and cannot commit their lives to the project.

2. How do I encode using XviD?

http://www.doom9.org/xvid.htm. As of Feb 13th, the interface has changed, however the options described in the guide work the same way.

3. What do all the different options mean?

Koepi's XviD Options Explained
Released: 08.03.2002, 11:00h CET
V1.3 of XviD Options Explained can be found at http://nic.dnsalias.com/xvid.html (beware - outdated now!)

Iago's two pass walkthrough
http://nic.dnsalias.com/xvid.html (beware - outdated now!)

VHQ Manual by Syskin
http://forum.doom9.org/showthread.php?s=&threadid=45746 (beware - outdated now!)

"The" Lumi Masking Thread
http://forum.doom9.org/showthread.php?s=&threadid=31301 (beware - outdated now!)

4. Is XviD better than DivX?

Read the codec comparison at http://www.doom9.org/codecs-103-1.htm and try to make up your own mind. Only you can decide what's best for you ;)

5. Where can I get XviD binaries?

Koepi's binaries: http://www.koepi.info/
Nic's binaries: http://nic.dnsalias.com/


6. Which quantizer mode should I use?

It is best to think of the MPEG quantizer as "sharpening" the image, and the H.263 quantizer as "softening" it. For high bitrates, you will find that MPEG quantization preserves more detail - for low bitrates, the smoothing of H.263 will give you less block noise.

However with the introduction of New Modulated HQ it may be considered the other way round. Modulated means switching between the two (MPEG/H263). More can be found in iago's guide and by searching this forum. Modulated Quants actually break the MPEG-4 spec so it is perhaps not best to use them. They also cannot be used with B-Frames correctly.
Koepi's post here may help: http://forum.doom9.org/showthread.ph...peg#post258145
(beware - outdated now!)

7. What to do if I get green and or pink blocks?

Some versions released after 2/2/2003 had this problem. It should be fixed now so try out the latest binaries.
(beware - outdated now!)

8. What filter should I use to play back XviD encoded videos?

The two main filters of choice are:
Nic's XviD DShow Filter ( http://nic.dnsalias.com )
or
Milan's FFDShow ( http://sourceforge.net/project/showf...group_id=53761 )
(As a general rule, get the latest version, even if it is alpha)

Although FFDShow has more options, it is not based on the XviD project and may contain incompatibilities from time to time. It is advised to try both and see what works best for you.
(These filters do not decode audio! only video! XviD does not decode or deal with audio in anyway)

9. What is Lumi masking?

Lumi masking is a first 'psychological' innovation in XviD; it is supposed make use of the fact that the human eye tends to notice encoding errors less if they happen in very dark or very bright parts of the picture. XviD is - in contrast to DivX - capable of using different quantizers for each macroblock. Lumi-masking compresses very dark or bright areas stronger than medium ones. So it will use less bits on some frames in the second pass than in the first pass. The saved bits are of course spent again and that way we gain a bit of quality in the medium-brightness part of the picture. As it is experimental, you may sometimes notice more blocks than when it is disabled.

10. What is the Chroma Optimiser

Chroma optimizer reduces PSNR by it's nature. The _mathematical_ deviation to the original picture will get bigger - but the subjective image quality will raise (as mentioned, the "stair step artifacts" get less).
Though some people reported problems with complete colour mismatches
It's on the debug-tab for a reason: it _certainly_ needs testing.

11. Why are there new binaries on a daily basis?

XviD is still in alpha state and under heavy development.
(beware - outdated now!)

12. Can I start using XviD now and will I be able to play files created with today's build once the final version comes out?

As XviD is creating MPEG4-compliant video streams, you can play your movies encoded today with any MPEG4-compliant decoder (i.e. any future version of XviD, or other MPEG4 players). XviD will, however, incorporate new features in the future such as B-frames, which cannot be played with the current build of either XviD or DivX.

13. What does the quality mode do?

The quality mode chooses an "average quantizer" for the entire video. It is similar to setting a quantizer in the "1-pass - quantizer" mode, though the quality mode lets you have a quantizer of say 4.5. In the case of 4.5, the 1st frame would be encoded with 4, the second with 5, the third with 4, the fourth with 5, etc., so that the "average" quantizer at the end of the video will be 4.5. The equation that gives you the "average quantizer" is:

((MaxQuant-MinQuant)/100 * (100-quality)) + MinQuant

(beware - outdated now!)

14a. What's the difference between Payback with bias and Payback proportionally?

Bias bitrate payback merely adds reserve bytes / payback delay to a frame regardless of it's size whereas proportional adds fewer bytes to smaller frames and more bytes to larger frames.
(beware - outdated now!)

14b. Thx for the info But what are the advant/disadvant of each?

Bias won't quickly use up the reserve on a demanding scene after a still / highly compressible sequence in the video but might use too much on an easy scene following such a sequence such as stationary text on a static background.
(beware - outdated now!)

15. I want to playback this movie I d/l'ed but there is no sound!
XviD is a video codec, thus has nothing to do with sound. Anyways, go to the download-section and fetch the audio-playback-filters for ac3, you're most likely lacking them.
You may also need an Ogg Vorbis filter which can be found @ http://tobias.everwicked.com/oggds.htm

16. I only get a green/no picture on playback!
Several reasons are possible: your VGA card can't cope with the resolution of the video - install the DivX-G400-patch from the download-section.
You installed the Nimo pack? The Nimo Codec Pack is evil[tm]! Happy reformating and fresh-installing your system! After that, stick with ffdshow or the XviD decoders. Just install the codecs you need, and no bloated packs!
FFDShow can be downloaded here: http://sourceforge.net/project/showf...group_id=53761

17. Are B-Frames safe to use?
syskin explains the current B-Frame bugs here:
http://forum.doom9.org/showthread.php?s=&threadid=47381
(beware - outdated now!)

18. How does Q-Pel work and when should I use it?
syskin & Koepi explain the state of Quarter Pel here:
http://forum.doom9.org/showthread.ph...pel#post225242
(beware - outdated now!)

19. How do I get the latest CVS sourcecode?
Download WinCVS and use
cvs -d:pserver:anonymous@cvs.xvid.org:/xvid co -R -r dev-api-4 xvidcore
cvs -d:pserver:anonymous@cvs.xvid.org:/xvid co -R -r dev-api-4 vfw
To get the dev-api-3 branch. Read more about it at www.xvid.org.

20. Is packed bitstream safe to use?
It is safer to have it turned off. Read more about it here:
http://forum.doom9.org/showthread.php?s=&threadid=67788
(beware - outdated now!)
More up to date opinions/info:
http://forum.doom9.org/showthread.php?s=&threadid=72903

21. What is meant by mod16/mod8/mod4 in concern to resolutions?
This refers to the resolution being able to be divided by a number cleanly. i.e. mod16 refers to resolutions such as 640x480, 720x576, etc. where both the horizontal and vertical are divisible by 16.

If you have downloaded a movie then you will get no other help here! We do not help with piracy of movies!
(beware - will never be outdated!)

Last edited by Koepi; 7th May 2008 at 05:59. Reason: Added my site for binary-downloads again
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