This file documents the ``Extended'' VLC Video CD Plugin Copyright (C) 2003, 2004 Rocky Bernstein (rocky@panix.com) Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with the Invariant Sections being ``Free Software'' and ``Free Software Needs Free Documentation'', with the Front-Cover Texts being ``A GNU Manual,'' and with the Back-Cover Texts as in (a) below. (a) The Free Software Foundation's Back-Cover Text is: ``You have freedom to copy and modify this GNU Manual, like GNU software. Copies published by the Free Software Foundation raise funds for GNU development.'' ----------------------------------------------------------------- Quick start ----------------------------------------------------------------- The newer Video CD plugin (using libcdio and vcdimager) has some navigation and playback capabilities. However full integration with into vlc is a bit lacking and will probably take some a bit of work and time. Although, this plugin replaces the older VCD plugin, the old plugin is still built and installed and used when the newer plugin is not found. This document describes only the newer VCD plugin. The next section is a general overview of Video CD's in general. If you are in a hurry to find out how to use this plugin or know this already, this section can be skipped. After that we describe the terms and concepts used in the remainder Again, in a hurry, this section can be skipped or skimmed. If you come across a term like "segment," or "lid" that confuses you, look in this section. The next section describes the MRL format that this plugin uses. If you want to know how to control where to start playing, read this. Even if you are familiar with vlc MRL's, you probably want to look at this section. Some of the units in a VCD are a little different than those in a DVD or audio CD. The next section gives key bindings that are used by this plugin. Again to be able to control the plugin, especially for playback control, you may need to read this section. The next section describes the configuration parameters you can set for the plugin. Most of the default values I hope are what most people will want to start out with. But for fine control of the defaults, read this section. One configuration variable is the debug output. The next section describes the meaning of debug flags and how to troubleshoot the plugin. ----------------------------------------------------------------- About VCDs, SVCDs, and XVCDs. ----------------------------------------------------------------- From: http://www.vcdhelp.com/vcd VCD stands for 'Video Compact Disc' and basically it is a CD that contains moving pictures and sound. If you're familiar with regular audio/music CDs, then you will know what a Video CD looks like. A VCD has the capacity to hold up to 74/80 minutes on 650MB/700MB CDs respectively of full-motion video along with quality stereo sound. VCDs use a compression standard called MPEG to store the video and audio. A VCD can be played on almost all standalone DVD Players and of course on all computers with a DVD-ROM or CD-ROM drive with the help of a software based decoder / player. It is also possible to use menus and chapters, similar to DVDs, on a VCD and also simple photo album/slide shows with background audio. The quality of a very good VCD is about the same as a VHS tape based movie but VCD is usually a bit more blurry. If you want better quality checkout SVCD,CVD or DVD. From: http://www.vcdhelp.com/svcd.htm SVCD stands for "Super VideoCD". A SVCD is very similar to a VCD, it has the capacity to hold about 35-60 minutes on 74/80 min CDs of very good quality full-motion video along with up to 2 stereo audio tracks and also 4 selectable subtitles. A SVCD can be played on many standalone DVD Players and of course on all computers with a DVD-ROM or CD-ROM drive with the help of a software based decoder / player. It is also possible to use menus and chapters, similar to DVDs, on a SVCD and also simple photo album/slide shows with background audio. The quality of a SVCD is much better than a VCD, especially much more sharpen picture than a VCD because of the higher resolution. But the quality depends how many minutes you choose to store on a CD, less minutes/CD generally means higher quality. From: http://www.vcdhelp.com/xvcd.htm XVCD stands for eXtendedVCD. XVCD has same features as VCD but it is possible to use higher bitrates and higher resolution to get higher video quality. XVCD is basicly everything that uses MPEG1 video, is not within the VCD standard and burnt in "VCD"-Mode. XSVCD stands for eXtendedSVCD. XSVCD has same features as SVCD but it is possible to use higher bitrates and higher resolution to get higher video quality. XSVCD is basicly everything that uses MPEG2 video, is not within the SVCD standard and burnt in "SVCD"-Mode. ----------------------------------------------------------------- Concepts used by this plugin. ----------------------------------------------------------------- The remote control of a Video CD players (or the front panel) generally has special keys or buttons. The author of a Video CD can assign what action to use when these buttons are pressed. They buttons are: RETURN: Often used to return to the previous menu or previouly interruped video segment. DEFAULT: Possibly take the default selection value. This function can only be assigned when the LID refers to in a "Program Selection List" or "Extended Program Selection List" NEXT: Possibly the next entry, chapter, track, or menu. PREVIOUS: Possibly the previous entry, chapter, track, or menu. Contiguous non-overlapping regions of a Compact Disc are called "Tracks". The sum of the tracks forms the entire CD. The CD specifications standards say that between tracks there is to be a 150-sector gap. In the MRL list described below, we generally don't list the first track which we would call call "Track 0", but other tools like VCDimager, cdinfo, and the CD-reading world in the general call this "Track 1". This first track usually contains an ISO 9660-format filesystem with metadata describing what's on the CD. It may also contain "segments" or small MPEGs that generally make up still frames and menus. Aside from the segments which are merely only parts of track 0, it doesn't make sense to try to "play" track 0 (or track 1 depending on how you want to count), which is why we don't list it. It seems natural to call the first thing you would want to play "track 1" (which in fact is track 2 to everyone else). There are two other units that this plugin lists and are used internally. One we call an "entry". This is a starting point of a track which can include the beginning of the track, and when an entry points to the beginning of a track, it is equivalent to listing the track. However Video CD's often have multiple entry points into a track. Logically this corresponds to a "Chapter" or "Scene" of a larger uninterruptable unit. One might think a CD "track" could serve this purpose with a collection of tracks making up a work or movie. Alas, there is "track pregap" space between tracks which appear as a time gaps when hardware players go between tracks - something that doesn't have to happen switching between entries because there in fact is no gap. Another unit we use is a called a "segment." These are just the playable units in track 0. Segments come in fixed-length units so several may be combined to form a single logical playable unit. Still frames for menus are segments. A menu doesn't have to have a still-frame associated with it; a menu might be implemented as a short looped movie clip. But all still frames are segments. Also, Video CD specifications allow still frames to have higher resolution than motion clips. All segments reside in track 0. A "list ID" (also called a LID and and is one greater than a Play Sequence descripter or "PSD" number) combines "entries" and "segments" and "tracks" together with some navigation logic. "Playback Control" (acronym PBC) is simply starting playback at a particular LID, and unless otherwise specified you'd start with the first playback item which we call P1. Below we will refer to an "item" as combination of a unit name (track, entry, segment, playback) and a whole number. ----------------------------------------------------------------- MRLS: ----------------------------------------------------------------- This vlc Video CD plugin, identifies itself in the vlc GUI preferences vcdx. It also registers itelf to handle a class of MRL's that start with vcdx://. The VCDX MRL takes the following form: vcdx://[path to file or vcd device][@[letter]number]] (Note: eventually the trailing "x" will be dropped. In MRL's "vcd" works as well as "vcdx". A simple vcdx:// runs the default item (e.g. perhaps track 1 or the playback control) the default VCD device (perhaps /dev/cdrom). Whether to use playback control and the default device are user-configurable. It is however also possible to specify both Video CD device/filename and the kind of item explicitly in the MRL. For example vcdx:/dev/dvd specifies the default entry using device /dev/dvd which might useful if this is your DVD which is different than your CD-ROM device and your DVD drive can play CD's. And vcdx://test_svcd_ntsc.cue specifies the cue file for CD image on disk. (test_svcd_ntsc.bin is the corresponding bin file, but using that won't work.) After the optional device name or file name, you can name the kind of unit which preceded by an '@'. An MRL which ends in an @ is like not adding it at all: the default entry type and number is used. Items come in 4 flavors: "Track," "Entry," "Playback," and "Segment." See the preceding section for an explaination of these terms. These units are indicated with the capital first letter of each type: T, E, P, S, s. --- In the future when we are able to control MRL display: An uppercase S in the MRL display indicates a NTS segment while a lowercase S indicates a PAL segment. ---- However when you enter a MRL, the case of these letters is insignificant. You can configure various things that affect MRLs are selected when there is some ambiguity in the MRL name. vcdx-PBC sets whether to to use PBC in a MRL is none is given. Another configuration setting, vcdx-device, determines what device to use if that part is not given. Some examples of MRLS are given below. In the examples, we assume the following configuration settings: vcdx-PBC=1 vcdx-device=/dev/cdrom vcdx:// - Play (navigate) default item (in this case Entry ID 0) from the default device (in this case set to /dev/cdrom) vcdx://@ - same as above vcdx:///dev/cdrom@ - same effect as above since the default device is set to /dev/cdrom. vcdx:///dev/cdrom@E0 - same as above. But note that this is because we have autoplay:entry which is no longer the default value vcdx:///dev/cdrom2@ - Play (navigate) the default item of /dev/cdrom2 vcdx:///dev/cdrom2 - should be same as above but is currently broken? vcdx:///dev/cdrom2@T1 - Play Track 1 from /dev/cdrom2 vcdx:///dev/cdrom@S1 - Play segment 1 from /dev/cdrom. This assumes there *is* a segment 1. Check the MRL list to see if that is the case. vcdx://@P1 - Play LID item 1 from default device If there is no playback control, MRL will get converted into vcdx://@E0. Again check the MRL list to see if there is a P1. vcdx://@P1* - probably same as above. vcdx:///dev/cdrom@E1 - Play Entry id 1 from default device vcdx://@S0 - Play segment 0 from default device vcdx://@3 - Play track 3 from default device vcdx:///dev/cdrom2:1 - Play track 1 from /dev/cdrom2 vcdx:///tmp/ntsc.cue@ - Play default item (E0) of /tmp/ntsc.bin. Note trailing @ vcdx://ntsc.cue/@E0 - Play entry 0 of ntsc.bin vcdx:///tmp/ntsc.nrg/@E0 - Play entry 0 of /tmp/ntsc.nrg (Nero file) Works for some simple Nero images. ----------------------------------------------------------------- Key bindings and non-PBC navigation. ----------------------------------------------------------------- At present vlc doesn't have special hot-keys for "NEXT", "PREVIOUS", "RETURN" or "DEFAULT". So we use some of other hot-key names that don't seem to correspond to anything for a VCD. The key mapping names are: VLC NAME VCD NAME -------------------------- NAVIGATE UP RETURN NAVIGATE DOWN DEFAULT NAVIGATE LEFT PREVIOUS NAVIGATE RIGHT NEXT Also this plugin understand numeric input. Since the hot-keys don't have assignments for numbers, the digits on the keyboard (also available from the keypad if num-lock is on) are hard-coded. Even though this isn't customizable, it's probably what most people would expect and want. The enter a number just type the digits of the number. To finish specifying a number use the whatever key is bound to vlc's "ACTIVATE" hot key - the default value is the "Enter" key. However the next/previous/return buttons can be prefaced with a number and that has the effect of hitting that button that many times. So let's say you want to go forward 5 "Chapters" and hitting the "Next" key 5 times would do that Instead, you could just enter the digit 5 followed by the key that is assigned to "NAVIGATE RIGHT", probably the right-arrow key. If you have better suggestions as to what functions the VCD buttons would be better bound to how what fixed algorithm to use when not in PBC, let me know. ----------------------------------------------------------------- Configuration settings: ----------------------------------------------------------------- Configuration settings in xine are generally put in ~/.vlc/vlcrc, but can be configured via a vlc GUI. A description of the ones specific to VCDX are listed below. - - vcdx-device This specifies the name of the video device that will be used by default. If you don't specify anything, the plugin scan for a suitable CD-ROM device containing a Video CD in it. The default device in a MRL when none is listed. The default is determined by the appropriate name for the OS that you are running. - - vcd-debug An integer (interpreted as a bit mask) which shows additional debugging information see the Debugging Section below for more information about the bits that can be set. ----------------------------------------------------------------- Troubleshooting Guide ----------------------------------------------------------------- The VCD plugin leaves a bit to be desired and has many bugs. I expect that there will not be covered below. But the below is a start. This gives higher-level troubleshooting. More detailed and lower-level information is given in the next section DEBUGGING. Problem: something doesn't work. Start at step -1. Problem: The program gets a SEGFAULT or gives core dump. Start at step 0. Problem: I don't get anything playing. I can't even get information listed in "Media and Stream Information" or the playlist. Determination: start at step 1. Problem: Okay, I something plays menu now. But I don't see information about the CD in the playlist. Determination: start at step 5. -1. (Something doesn't work.) A lot of what is put here really is applicable to reporting problems and troubleshooting in vlc and the concepts really apply to any sort of bug reporting. When reporting a problem it's helpful to have facts: a) the version of vlc) you are using b) the OS you are running on c) the version of libcdio and/or libcddb you are using versions of libcdio and libcddb can be obtained by running pkg-config --modversion libcdio pkg-config --modversion libvcdinfo d) what you input or requested (e.g. the full command line entered - if it is possible to reproduce the problem by giving a commandline that is desirable since it is probably the simplest way to convey exactly what was requested) People often give (some part) of an error message neglecting to also include what was requested or entered that led to the output. e) The setting for this plugin. That is the values of the variables that start cddax- listed above. On Unix this can generally be found in ~/.vlc/vlcrc f) Exactly the messages that were what given. You can turn increase the verbosity level by setting "verbosity=2" in the vlc preferences files. On Unix the preferences file is generally in ~/vlc/.vlcrc but there are GUI ways to set this too. Give everything that is in the message log. 0. (The program gets a SEGFAULT or gives core dump.) Get and send a stack trace. In addition to -1. Make sure the program has been compiled with debugging symbols put into the code. This is usually done by having the "-g" flag set when compiling the program. You can get a strack trace the GNU debugger using the "where" command. For example on this might work: gdb vlc *name-of-corefile* where 1. (I don't get anything playing. I can't even get information listed in "Media and Stream Information" or the playlist) Do you even have the plugin loaded? When you run the vlc GUI, under Settings/Preferences you should see a "plugins" expandable list and under that another "access" list do you see a expandalbe entry under "access" labeled "vcdx"? If so, skip on to step 2. a) If no "vcdx" expandable list, thent the VCDX plugin isn't loaded. Does a shared object exist? The plugin shared object is called "libvcdx_plugin.so" It should be in the directory that has ...vlc/access. If this isn't around you need to build and install the VCDX plugin. b) if libvcdx_plugin.so is in the fileystem, there might be a loader error; perhaps libcdio or libvcdinfo are not installed or are the wrong version. Use ldd on the file to see that it has all of the libraries dependencies satisfied. Also you might be able check if there was an attempt to load it by tracking system calls. On Linux and other OS's) "strace" can be used to see if the file gets accessed. On Solaris use "truss". For example on Linux, amonst the many line of output when I run "strace -e trace=file vlc" I see this amongst lots of other output: ... stat64("/usr/local/lib/vlc/access/libvcdx_plugin.so", {st_mode=S_IFREG|0755, st_size=302990, ...}) = 0 open("/usr/local/lib/vlc/access/libvcdx_plugin.so", O_RDONLY) = 5 The parameters inside the calls may be different depending on where vlc is installed and what release is installed. If the the file is found and "opened", There may also be a message may under "setup/logs". 2. (There plugin was loaded and preferences found). In the "vcdx" tab of preference. An important selection is "vcdx-device." If this is set to the empty string, VCDX will try to scan your drives for a suitable device if the driver has the capability to scan for drives. However you can set the device to something of your choosing. On GNU/Linux, this may be "/dev/cdrom" and on Solaris it may be "/vol/dev/aliases/cdrom0". If you set this field, make sure these are correct for your particular setup. For example, I generally play out of the DVD device and this is called /dev/dvd rather than /dev/cdrom. 3. (Video CD Setup devices seems correct and there is a CD in the drive). when you run vlc vcdx:// you should see your CD disk light go on if you have one. And the CD should be read. a. If not something's wrong like step 2. Another tack may be to try to read a disk image of a Video CD and thus elimate any problems with hardware. You can get a test Video CD disk image to test here: http://www.vcdimager.org/pub/vcdimager/examples/test_svcd/test_svcd_pal.zip After unzipping this run there should be files test_svcd_pal.cue and test_svcd_pal.bin. Get out of xine and run from the directory that contains those files: vcdx://test_svcd_pal.cue@E0 If you see something playing then this is a hardware problem. ----------------------------------------------------------------- Debugging ----------------------------------------------------------------- **General vlc debugging... Before delving to things specific to this plugin, some preparation may be in order. You'll probably want to configure vlc with "--enable-debug". plugin with debug information. Instead of "make'ing" with "make", use "make debug" and instead of installing using "make install" use "make install-debug". I use gdb to debug. Debugging vlc with the entire suite of plugins under gdb is slow because it has to read in symbol tables from all the plugins. There are two ways to make loading faster when debugging. The simplest is just to go to the plugin directory and remove unused plugins. Another approach is create a new directory and make (symbolic) links into the complete plugin directory. Another way to speed up gdb loading is to attach the debugger after vlc has started up via a command like: gdb -p *pid-of-vlc-process* **vcdx debugging... It's a fact of life that this plugin is in an incomplete state and has bugs. So to facilitate tracking down problems we let you see what's going on dynamically. Various debugging settings will cause output to appear on vlc plugin log and/or "standard error" (assuming you've run xine in a way that you can capture this). You think of debug switches as a bit mask, that you specifiy as an integers the various "bit" values (given in decimal) are listed below. name value description ------ ---------- ----------- meta info 1 Trace Meta information event info 2 Trace keyboard events MRL 4 Things involved getting lists of what's in the VCD ext call 8 Trace vlc calls to the plugin routines all calls (10) 16 Trace all calls LSN (20) 32 Trace updates to the Logical sector number (basically reads) PBC (40) 64 Trace things involved with playback control libcdio (80) 128 Turn on CDIO debugging seek-set (100) 256 Trace "seek set" calls seek-cur (200) 512 Trace "seek cur" calls still (400) 1024 Trace Still-frames vcdinfo (800) 2048 Turn on VCDINFO debugging **Video CD debugging... The tool vcd-info from the cdio branch of vcdimager can be used to show the entire contents of a Video CD or selected portions of that. Until the cdio branch of vcdimager is completely merged with vcdimager, the cd-info branch vresion has a few more features. (However consult vcdimager for complete of the program). vcdxrip can be used to extract portions of a Video CD and or create an XML description file of the Video CD. This XML file and the extracted files can be used by vcdxbuild to recreate another Video CD. And finally see also tools cd-info an cd-read from libcdio. ----------------------------------------------------------------- Other references ----------------------------------------------------------------- http://www.vcdhelp.com/ http://www.vcdimager.org/ http://www.vcdimager.org/guides/#guides $Id$