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267 lines
13 KiB
HTML
267 lines
13 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML>
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<HEAD>
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<TITLE>CD, DVD, VCD - MPlayer - The Movie Player for Linux</TITLE>
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<LINK REL="stylesheet" TYPE="text/css" HREF="default.css">
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<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1">
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</HEAD>
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<BODY>
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<H2><A NAME="drives">4.1 CD/DVD drives</A></H2>
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<P>Linux documentation excerpt:</P>
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<P>Modern CD-ROM drives can attain very high head speeds, yet some CD-ROM drives
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are capable of running at reduced speeds. There are several reasons that might
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make you consider changing the speed of a CD-ROM drive:</P>
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<UL>
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<LI>There have been reports of read errors at high speeds, especially
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with badly pressed CD-ROMs. Reducing the speed can prevent data loss under
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these circumstances.</LI>
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<LI>Many CD-ROM drives are annoyingly loud, a lower speed may reduce the
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noise.</LI>
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</UL>
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<P>You can reduce the speed of IDE CD-ROM drives with <CODE>hdparm</CODE> or a
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program called <CODE>setcd</CODE>. It works like this:</P>
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<P> <CODE>hdparm -E [speed] [cdrom device]</CODE></P>
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<P> <CODE>setcd -x [speed] [cdrom device]</CODE></P>
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<P>You can also try</P>
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<P> <CODE>echo current_speed:4 > /proc/ide/[cdrom device]/settings</CODE></P>
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<P>but you will need root privileges. The following command may also help:</P>
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<P> <CODE>echo file_readahead:2000000 > /proc/ide/[cdrom device]/settings</CODE></P>
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<P>This sets prefetched file reading to 2MB, which helps with scratched CD-ROMs.
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If you set it to too high, the drive will continuously spin up and down, and
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will dramatically decrease the performance.
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It is recommended that you also tune your CD-ROM drive with
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<CODE>hdparm</CODE>:</P>
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<P> <CODE>hdparm -d1 -a8 -u1 (cdrom device)</CODE></P>
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<P>This enables DMA access, read-ahead, and IRQ unmasking (read the
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<CODE>hdparm</CODE> man page for a detailed explanation).</P>
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<P>Please refer to "<CODE>/proc/ide/[cdrom device]/settings</CODE>" for
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fine-tuning your CD-ROM.</P>
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<P>SCSI drives do not have a uniform way of setting these parameters (Do you
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know one? Tell us!) There is a tool that works for
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<A HREF="http://das.ist.org/~georg/">Plextor SCSI drives</A>.</P>
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<P>FreeBSD:</P>
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<P> Speed: <CODE>cdcontrol [-f device] speed [speed]</CODE></P>
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<P> DMA: <CODE>sysctl hw.ata.atapi_dma=1</CODE></P>
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<H2><A NAME="dvd">4.2 DVD playback</A></H2>
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<P>For the complete list of available options, please read the man page.
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The Syntax for a standard Digital Versatile Disc (DVD) is as follows:</P>
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<P><CODE>mplayer -dvd <track> [-dvd-device <device>]</CODE></P>
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<P>Example: <CODE>mplayer -dvd 1 -dvd-device /dev/hdc</CODE></P>
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<P>The default DVD device is <CODE>/dev/dvd</CODE>. If your setup differs,
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make a symlink or specify the correct device on the command line with the
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<CODE>-dvd-device</CODE> option.</P>
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<H4>New-style DVD support (mpdvdkit2)</H4>
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<P>MPlayer uses <CODE>libdvdread</CODE> and <CODE>libdvdcss</CODE> for
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DVD decryption and playback. These two libraries are contained in the
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<CODE>libmpdvdkit2/</CODE> subdirectory of the MPlayer source tree, you
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do not have to install them separately. We opted for this solution because
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we had to fix a <CODE>libdvdread</CODE> bug and apply a patch which adds
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<B>cracked CSS keys caching support</B> to <CODE>libdvdcss</CODE>. This results
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in a large speed increase because the keys do not have to be cracked every time
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before playing.</P>
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<P>MPlayer can also use system-wide <CODE>libdvdread</CODE> and
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<CODE>libdvdcss</CODE> libraries, but this solution is <B>not</B> recommended,
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as it can result in bugs, library incompatibilities and slower speed.</P>
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<H4>DVD Navigation support (dvdnav)</H4>
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<P>Support for DVD navigation via <CODE>dvdnav</CODE> was being worked on, but
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it was never finished properly and it is currently unmaintained. Who knows, it
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might even compile.</P>
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<H4>Old-style DVD support - OPTIONAL</H4>
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<P>Useful if you want to play encoded VOBs from <B>hard disk</B>. Compile and
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install <B>libcss</B> 0.0.1 (not newer) for this (If MPlayer fails to
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detect it, use the <CODE>-csslib /path/to/libcss.so</CODE> option). To use it,
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you need to be root, use a suid root MPlayer binary or let MPlayer call the
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suid-root fibmap_mplayer wrapper program.</P>
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<H4>DVD structure</H4>
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<P>DVD disks have 2048 bytes per sector with ECC/CRC. They usually have an UDF
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filesystem on a single track, containing various files (small .IFO and .BUK
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files and big (1GB) .VOB files). They are real files and can be copied/played
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from the mounted filesystem of an unencrypted DVD.</P>
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<P>The .IFO files contain the movie navigation information (chapter/title/angle
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map, language table, etc) and are needed to read and interpret the .VOB
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content (movie). The .BUK files are backups of them. They use <B>sectors</B>
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everywhere, so you need to use raw addressing of sectors of the disc to
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implement DVD navigation or decrypt the content.</P>
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<P>The whole old-style DVD support with <CODE>libcss</CODE> therefore needs a mounted DVD
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filesystem and raw sector-based access to the device. Unfortunately you must
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(under Linux) be root to get the sector address of a file. You have the
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following choices:</P>
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<UL>
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<LI>Be root or use a suid-root mplayer binary.</LI>
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<LI>Let MPlayer call the suid-root fibmap_mplayer wrapper program to access
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the DVD (used in the old-style DVD playback over <CODE>libcss</CODE>).</LI>
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<LI>Don't use the kernel's filesystem driver at all and reimplement it in
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userspace. <CODE>libdvdread</CODE> 0.9.x and <CODE>libmpdvdkit</CODE> do this (new-style DVD
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support). The kernel UDF filesystem driver is not needed as they already
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have their own builtin UDF filesystem driver. Also the DVD does not have to
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be mounted as only the raw sector-based access is used.</LI>
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</UL>
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<P>Sometimes <CODE>/dev/dvd</CODE> cannot be read by users, so the <CODE>libdvdread</CODE>
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authors implemented an emulation layer which transfers sector addresses to
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filenames+offsets, to emulate raw access on top of a mounted filesystem
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or even on a hard disk.</P>
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<P><CODE>libdvdread</CODE> even accepts the mountpoint instead of the device name for raw
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access and checks <CODE>/proc/mounts</CODE> to get the device name. It was
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developed for Solaris, where device names are dynamically allocated.</P>
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<P>The default DVD device is <CODE>/dev/dvd</CODE>. If your setup differs,
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make a symlink, or specify the correct device on the command line with the
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<CODE>-dvd-device</CODE> option.</P>
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<H4>DVD authentication</H4>
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<P>The authentication and decryption method of the new-style DVD support is done
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using a patched <CODE>libdvdcss</CODE> (see above). The method can be specified through the
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environment variable <CODE>DVDCSS_METHOD</CODE>, which can be set to
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<CODE>key</CODE>, <CODE>disk</CODE> or <CODE>title</CODE>.</P>
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<P>If nothing is specified it tries the following methods
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(default: key, title request):</P>
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<OL>
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<LI><B>bus key:</B> This key is negotiated during authentication (a long mix
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of ioctls and various key exchanges, crypto stuff) and is used to encrypt
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the title and disk keys before sending them over the unprotected bus
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(to prevent eavesdropping). The bus key is needed to get and predecrypt the
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crypted disk key.</LI>
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<LI><B>cached key:</B> MPlayer looks for already cracked
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title keys which are stored in the <CODE>~/.mplayer/DVDKeys</CODE> directory
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(fast ;).</LI>
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<LI><B>key:</B> If no cached key is available, MPlayer tries to
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decrypt the disk key with a set of included player keys.</LI>
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<LI><B>disk:</B> If the key method fails (e.g. no included player keys),
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MPlayer will crack the disk key using a brute force algorithm.
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This process is CPU intensive and requires 64 MB of memory (16M 32Bit
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entries hash table) to store temporary data. This method should always
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work (slow).</LI>
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<LI><B>title request:</B> With the disk key MPlayer requests the crypted title
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keys, which are inside <I>hidden sectors</I> using <CODE>ioctl()</CODE>.
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The region protection of RPC-2 drives is performed in this step and may
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fail on such drives. If it succeeds, the title keys will be decrypted with
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the bus and disk key.</LI>
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<LI><B>title:</B> This method is used if the title request failed and does
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not rely on any key exchange with the DVD drive. It uses a crypto attack to
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guess the title key directly (by finding a repeating pattern in the
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decrypted VOB content and guessing that the plain text corresponding to the
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first encrypted bytes is a continuation of that pattern).
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The method is also known as "known plaintext attack" or "DeCSSPlus".
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In rare cases this may fail because there is not enough encrypted data on
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the disk to perform a statistical attack or because the key changes in the
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middle of a title. This method is the only way to decrypt a DVD stored on a
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hard disk or a DVD with the wrong region on an RPC2 drive (slow).</LI>
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</OL>
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<P>RPC-1 DVD drives only protect region settings through software.
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RPC-2 drives have a hardware protection that allows 5 changes only. It might
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be needed/recommended to upgrade the firmware to RPC-1 if you have a RPC-2 DVD
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drive. Firmware upgrades can be found on this
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<A HREF="http://www.firmware-flash.com">firmware page</A>. If there is
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no firmware upgrade available for your device, use the
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<A HREF="http://www.linuxtv.org/download/dvd/dvd_disc_20000215.tar.gz">regionset
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tool</A> to set the region code of your DVD drive (under Linux).
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<B>Warning:</B> You can only set the region 5 times.</P>
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<H2><A NAME="vcd">4.3 VCD playback</A></H2>
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<P>For the complete list of available options, please read the man page.
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The Syntax for a standard Video CD (VCD) is as follows:</P>
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<P><CODE>mplayer -vcd <track> [-cdrom-device <device>]</CODE></P>
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<P>Example: <CODE>mplayer -vcd 2 -cdrom-device /dev/hdc</CODE></P>
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<P>The default VCD device is <CODE>/dev/cdrom</CODE>. If your setup differs,
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make a symlink or specify the correct device on the command line with the
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<CODE>-cdrom-device</CODE> option.</P>
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<P><B>Note:</B> At least Plextor and some Toshiba SCSI CD-ROM drives have
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horrible performance reading VCDs. This is because the the CDROMREADRAW ioctl
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is not fully implemented for these drives. If you have some knowledge of SCSI
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programming, please <A HREF="tech/patches.txt">help us</A> implement generic
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SCSI support for VCDs.</P>
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<P>In the meantime you can extract data from VCDs with
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<A HREF="http://140.132.1.204/OS/Linux/packages/X/viewers/readvcd/">readvcd</A>
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and play the resulting file with MPlayer.</P>
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<H4>VCD structure</H4>
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<P>VCD disks consist of one or more tracks:</P>
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<UL>
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<LI>The first track is a small 2048 bytes/sector data track with an iso9660
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filesystem, usually containing Windows VCD player programs and maybe other
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information (images, text, etc).</LI>
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<LI>The second and other tracks are raw 2324 bytes/sector MPEG (movie) tracks,
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containing one MPEG PS data packet per sector instead of a filesystem.
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Similar to audio CD tracks, these tracks <B>cannot be mounted</B> (Did you
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ever mount an audio CD to play it?). As most movies are inside this track,
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you should try <CODE>-vcd 2</CODE> first.</LI>
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<LI>There exist VCD disks without the first track (single track and no
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filesystem at all). They are still playable, but cannot be mounted.</LI>
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</UL>
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<H4>About .DAT files:</H4>
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<P>The ~600 MB file visible on the first track of the mounted VCD is not a real
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file! It is a so called ISO gateway, created to allow Windows to handle such
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tracks (Windows does not allow raw device access to applications at all).
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Under Linux you cannot copy or play such files (they contain garbage). Under
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Windows it is possible as its iso9660 driver emulates the raw reading of
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tracks in this file. To play a .DAT file you need the kernel driver which can
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be found in the Linux version of PowerDVD. It has a modified iso9660
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filesystem (<CODE>vcdfs/isofs-2.4.X.o</CODE>) driver, which is able to emulate
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the raw tracks through this shadow .DAT file. If you mount the disc using
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their driver, you can copy and even play .DAT files with mplayer. But it
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<B>will not work</B> with the standard iso9660 driver of the Linux kernel!
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Use the <CODE>-vcd</CODE> option instead. Alternatives for VCD copying are
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the new <A HREF="http://www.elis.rug.ac.be/~ronsse/cdfs/">cdfs</A> kernel
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driver (not part of the official kernel) that shows CD <I>sessions</I>
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as image files and <A HREF="http://cdrdao.sourceforge.net/">cdrdao</A>, a
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bit-by-bit CD grabbing/copying application.</P>
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</HTML>
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