Difference between revisions of "Frequently Asked Questions"
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Copyright © 2002 -
Copyright © 2002 - the VideoLAN project
Frequently Asked Questions about VideoLAN.
Frequently Asked Questions about VideoLAN.
Revision as of 21:53, 29 May 2008
Copyright © 2002 - 2008 the VideoLAN project
Frequently Asked Questions about VideoLAN.
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. The text of the license can be found on the GNU website.
This is under rewriting
- 1 VideoLAN
- 2 Legal concerns
- 3 VLC media player
- 3.1 Where can I download VLC for Mac OS 9?
- 3.2 Does VLC support DVDs from all regions?
- 3.3 Where does VLC store its config file?
- 3.4 VLC has a strange behavior...
- 3.5 Videos are too dark
- 3.6 I cannot read DVDs!
- 3.7 The video runs but the picture is distorted
- 3.8 Video is choppy
- 3.9 Audio and video are out of sync
- 3.10 VLC crashes.
- 3.11 How can I take screenshots?
- 3.12 Where are my screenshots?
- 3.13 My file doesn't seem to work!
- 3.14 VLC doesn't display all subtitles
- 3.15 Why is my video purple? (a.k.a. the smurf effect)
- 4 VideoLAN streaming solution
- 5 Miscellaneous
What is VideoLAN? What is the VideoLAN Team?
VideoLAN is a group of people, the VideoLAN Team that produces free and open source software for video and multimedia purpose, released under the GNU General Public License.
It started as a student project at the French École Centrale Paris but is now a worldwide project with developers from 20 countries and millions of people using VideoLAN's software.
What is the legal structure of VideoLAN?
The "Club VideoLAN" is a project of the association Centrale Réseaux, which is a French non-profit organisation based at the École Centrale Paris. VideoLAN has its own bank account and is responsible of its finance in front of the board of Centrale Réseaux.
What is the differences between VLC, VLC media player, VideoLAN Client, VideoLAN Server and VideoLAN?
VLC media player is the official name of VideoLAN's main product, oftenly named VLC. VideoLAN Client is an ancient name of this product.
VideoLAN Server is another product of VideoLAN, but is discontinued since VLC media player can do more.
VideoLAN is NOT a software, see 1.1 of this FAQ.
How may I help VideoLAN?
You might either contribute time, material, or money. You DON'T NEED to be a programmer to help us. We are also always needing some translators. You will find all information you need on the contribute page.
May I use the VideoLAN logo?
You may freely use the VideoLAN logo using the following copyright:
Copyright (c) 1996-2003 VideoLAN. This logo or a modified version may be used or modified by anyone to refer to the VideoLAN project or any product developed by the VideoLAN team, but does not indicate endorsement by the project.
May I redistribute a piece of VideoLAN software?
You may distribute an original or modified version of a piece of VideoLAN software as long as you comply with its license terms. It is the GNU General Public License Version 2 (referred herein as GPL), and it is in the file named COPYING in our products. The easiest way to conform to the GPL is to accompany the product you want to distribute with its sources. For example, if you plan to distribute the lastest binary version of VLC, you should also include all the files listed on the VLC source code page. You do not need to bother explaining where the sources are, but the sources have to share the same media as the products. There are other ways to comply with the GPL, but this should be the simplest because it does not rely on a contract.
- You do not need to ask the VideoLAN team the permission to do so!
Is libdvdcss legal?
The use and distribution of the libdvdcss library is controversial in a few countries such as the United States because of a law called the DMCA (Digital Millennium Copyright Act). If you are unsure about the legality of using and distributing this library in your country, please consult your lawyer.
- Beware: VLC media player binaries are distributed with the libdvdcss library included.
What about personal/commercial usage?
Some of the codecs distributed with VLC are patented and require you to pay royalties to their licensors. These are mostly the MPEG style codecs.
With many products the producer pays the license body (in this case MPEG LA) so the user (commercial or personal) does not have to take care of this. VLC (and ffmpeg and libmpeg2 which it uses in most of these cases) cannot do this because they are Free and Open Source implementations of these codecs. The software is not sold and therefore the end-user becomes responsible for complying to the licensing and royalty requirements. You will need to contact the licensor on how to comply to these licenses.
This goes for playing a DVD with VLC for your personal joy ($2.50 one time payment to MPEG LA) as well as for using VLC for streaming a live event in MPEG-4 over the Internet.
VLC media player
Where can I download VLC for Mac OS 9?
Where did you read that a version of VLC for Mac OS 9 exists? There is not, and never will be, a version for Mac OS 9.
Does VLC support DVDs from all regions?
Well this mostly depends on your DVD drive. Testing it is usually the quickest way to find out. The problem is that a lot of newer drives are RPC2 drives these days. Some of these drives don't allow raw access to the drive untill the drive firmware has done a regioncheck. VLC uses libdvdcss and it needs raw access to the DVD drive to crack the encryption key. So with these drives it is impossible to circumvent the region protection. (This goes for all software. You will need to flash your drives firmware, but sometimes there is no alternate firmware available for your drive). On other RPC2 drives that DO allow raw access, it might take VLC a long time to crack the key. So just pop the disc in your drive and try it out, while you get a coffee. RPC1 drives should 'always' work regardless of the regioncode.
Where does VLC store its config file?
Currently, a config file is created on a per user basis (there is no global configuration file). If you modify the available options in VLC and save the new configuration, then a configuration file will be created in your user directory. The precise location of this file depends on the Operating System you are running:
- Linux / Unix:
$(HOME)/.config/vlc/vlcrc(v0.9.0 and above),
$(HOME)/.vlc/vlcrc(v0.8 and older)
- Mac OS X:
- Windows 95/98/ME:
- Windows XP/2000:
C:\Documents and Settings\%username%\Application Data\vlc\vlcrc
VLC has a strange behavior...
The first thing to do is to reset the VLC preferences in the preferences dialog of the application and restart VLC. If VLC doesn't even start anymore, delete VLC's configuration file (see the previous question to know about its location). Then restart VLC. If it does not get any better, read the following questions!
Videos are too dark
Often this is caused by video hardware overlay problems:
- If it is only one video then use the "Settings" menu, option "Extended GUI" and try to increase the Gamma value in the "Video" tab.
- Check your video card settings and turn off hardware video overlay. If the videos now play with proper lighting, then deinstalling and reinstalling the video drivers might help.
I cannot read DVDs!
Here are a few things to check:
- If you are on Linux, did you install the libdvdcss package?
- Do you have write access to your DVD device? For instance, under Unix:
# chmod 666 /dev/dvd
/dev/dvd is the device corresponding to your DVD drive.
The video runs but the picture is distorted
There is probably a problem with the output layer. There are several ways of troubleshooting it. First, try with another output plugin, for instance:
% vlc -V sdl % vlc -V x11
Second, change your screen depth and/or definition. It quite often helps. Lastly, if running Unix, have a look at your XFree86 video driver.
Video is choppy
Your system might be too slow to decode all pictures. It might be that your CPU basically is not fast enough. It can also be that the subsystem is misconfigured/misdriven, this happens for example under Redhat Linux. Here are some elements to improve speed:
- Turn on DMA on your DVD device, for instance:
- Under Linux:
# hdparm -d1 /dev/dvd
- Under Windows, go to the System section of the control panel, and go to the Hardware manager (it is sometimes in a separate tab, and sometimes, you have to go to the Advanced tab. Then, righ-click on your DVD player, and check the DMA checkbox.
- Upgrade to the latest driver for your video board
If you are running Linux, you can additionnaly upgrade to the latest XFree86 version. If supported, check that the xvideo plug-in is effectively used with:
% vlc -vvvv
- Stop other running applications...
- Try disabling framedropping. Framedropping allows VLC not to decode some pictures when the CPU is overloaded, but can result in choppier playback under certain conditions.
Framedropping behaviour can be configured in the Video preferences of VLC.
Audio and video are out of sync
Try using another audio output plugin and, under Unix, kill esd or artsd if they are running. If the problem is due to the input file, have a look at the "Audio desynchronisation compensation" option.
Increase the verbosity level (either in the preferences or with a -vvvv command line option) and look at the debug messages (in the terminal or in the Messages window).
If you are convinced that it is a bug in VLC, have a look at the bug reporting page.
On Debian Sarge, if it segfaults on TS or V4L, try removing
How can I take screenshots?
To take a snapshot of the video displayed by VLC, you just need to press the pre-defined snapshot hotkey:
- Windows / Linux / Unix: Ctrl-Alt-s
- Mac OS X: Command-Alt-s
To change it, go to Preferences -> Interface -> Hotkeys settings, check Advanced options, and set Take video snapshot.
You can also take a snaphot via the menu Video -> Snapshot.
To change the snapshot format or directory, go to Preferences -> Video.
Where are my screenshots?
If you haven't changed the snapshot directory in your preferences, your screenshots should go to:
My Documents\My Pictures\
- Linux / Unix:
- Mac OS X:
To change it, go to Preferences -> Video -> Video snapshot directory.
My file doesn't seem to work!
Are you sure VLC supports the file? Try checking the features page. If it supported and you compiled VLC yourself, check if you have downloaded and installed all the codecs correctly. If it is not supported, then you are out of luck for now.
- At present, especially WMV3, the most recent Real Player, and the most recent Indeo Video ("IV50", etc.) files are not supported by VLC and are not going to be in the near future.
VLC doesn't display all subtitles
If VLC has autodetected your subtitles file, or if you opened it manually, but VLC only diplays some subtitles from time to time, you will need to change the subtitles file encoding.
Go to Preferences -> Input / Codecs -> Other codecs -> Subtitles, and set Subtitle text encoding to the right one.
See this reference: ISO Standard for various characters sets.
Why is my video purple? (a.k.a. the smurf effect)
Not sure. But many people have fixed this problem by changing their video output module.
Go to Preferences -> Video -> Output modules, and set Video output module to something different, like DirectX video output. Be sure you have advanced options enabled to be able to access this option. Also, you might need to disable the "YUV -> RGB" checkbox in DirectX section of Preferences -> Video -> Output modules.
VideoLAN streaming solution
Do I need a "streaming server"?
Well, there are in fact two kinds of streaming: passive streaming in which a movie is sent by a server and watched by one or several client, and Video On Demand (VOD) in which each client asks for its own stream.
- In passive streaming, the client has no control upon the server, and must subscribe for instance to a multicast group to receive the stream. This kind of streaming needs a server able to send data on a network with a protocol such as UDP multicast or RTP, for instance VLS or VLC stream output. The client side needs a player supporting such protocols, as VLC does.
- In Video On Demand, no specific "streaming server" is required, but the client must be able to read the stream in real time, instead of just dowloading the whole video before one can start viewing it. A simple protocol such as HTTP is sufficient for Video On Demand, so you just have to put your movie on a web server, and use a clever player to view it in real time, VLC for instance ;-) However of course you will not be able to view movies in real time if your network is too slow, so you MUST check that the average bandwith of your network link is higher than the average bandwith of your movie (size / duration). If it is not the case, VLC will try to keep in real time as much as possible, so you will probably get only the audio track and no video.
VLC vs. VLS
Technically, there is an important difference:
- VLC opens all the system layers of the input stream, regenerate them all and then stream the result on the network or write it to a file. So VLC is good at streaming untrusted video and/or audio sources, like the video files found on the Internet and/or produced by non-professionnal software. VLC implements many muxers/demuxers (ps, ts, avi, ogg, mp4, ...) and many codecs, which allows to convert encapsulation formats and/or transcode an input stream on-the-fly ! VLC also has nice graphical interfaces.
- VLS only opens the highest system layers of the input stream and only has PS and TS demuxers. So VLS is good at streaming from trusted video and/or audio sources in PS or TS format produced by professional software or hardware like DVDs and DVB channels (satellite or digital terrestial TV) because it only regenerate the system layers that need to be regenerated, and no more. VLS is specially well designed to stream multiplexed TS streams, for instance a whole DVB transponder. VLS only has a TS muxer, doesn't do transcoding and doesn't have graphical interfaces.
Is it not a waste of time to develop both?
To understand this situation, you must consider the history of VideoLAN. Before VLC's stream output, we had two very different programs:
- VLS, a program written in C++ running under Linux, Mac OS X and Windows only, that is basically a MPEG Transport Stream engine, with a very basic telnet interface, which was used as a server;
You'll note VLS is not maintained anymore.
- VLC, a multi-platform program written in C, that implements demuxers, codecs, video and audio outputs and graphical interfaces, which was used as a client only.
In september 2002, some VLC developers had the idea of taking advantage of the multiple demuxers and codecs implemented in VLC to build a Stream Output whose ultimate goal was to be able to do transcoding. They wrote a stream output for VLC, that was released with VLC 0.5.0 in late January 2003. Introduced with the 0.8.0 release, VLC is able to transcode to any format it can read. Furthermore, starting with the 0.7.x series, VLC is able to stream multiple sources with one instance. This can be controlled with the VideoLAN (Media) Manager (VLM), which can be accessed through a telnet interface and a http interface.
But what is more important is that VLS and VLC developers are not the same people, and that they are free to write the software they prefer! That is how free software runs, and it has shown in the past that is was a good engine for innovation and enhancement.
Why are your mailing-lists and your website in english?
VideoLAN's developers come from all around the world and english is the only language they can use to communicate together. Although great care is given to the translation of VLC in various languages, maintaining translations of our website costs too much more time than we can afford.
What to do if I can't find an answer to my question here?
Have a look at the Wiki. There is another FAQ, which answers more questions on using and compiling the VideoLAN applications. Technical terms on streaming and multimedia are discussed too.
Search the forums for your question. There are many solutions to problems on using our programs.
If your question still was not answered, post it on the forums or mail a fitting mailing-list. More information on support provided by the project or consulting companies can be found on the support page.