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<chapter id="cd-dvd">
<title>CD/DVD usage</title>

<sect1 id="drives">
<title>CD/DVD drives</title>

<para>
Modern CD-ROM drives can attain very high head speeds, yet some CD-ROM drives
are capable of running at reduced speeds. There are several reasons that might
make you consider changing the speed of a CD-ROM drive:
</para>

<itemizedlist>
<listitem><para>
  There have been reports of read errors at high speeds, especially
  with badly pressed CD-ROMs. Reducing the speed can prevent data loss under
  these circumstances.
</para></listitem>

<listitem><para>
  Many CD-ROM drives are annoyingly loud, a lower speed may reduce the noise.
</para></listitem>
</itemizedlist>

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<sect2 id="drives_linux">
<title>Linux</title>

<para>
You can reduce the speed of IDE CD-ROM drives with <command>hdparm</command>,
<command>setcd</command> or <command>cdctl</command>. It works like this:
<screen>hdparm -E <replaceable>[speed]</replaceable> <replaceable>[cdrom device]</replaceable></screen>
<screen>setcd -x <replaceable>[speed]</replaceable> <replaceable>[cdrom device]</replaceable></screen>
<screen>cdctl -bS <replaceable>[speed]</replaceable></screen>
</para>

<para>
If you are using SCSI emulation, you might have to apply the settings to the
real IDE device, not the emulated SCSI device.
</para>

<para>
If you have root privileges the following command may also help:
<screen>echo file_readahead:2000000 &gt; /proc/ide/<replaceable>[cdrom device]</replaceable>/settings</screen>
</para>

<para>
This sets prefetched file reading to 2MB, which helps with scratched CD-ROMs.
If you set it to too high, the drive will continuously spin up and down, and
will dramatically decrease the performance.
It is recommended that you also tune your CD-ROM drive
with <command>hdparm</command>:
<screen>hdparm -d1 -a256 -u1 <replaceable>[cdrom device]</replaceable></screen>
</para>

<para>
This enables DMA access, read-ahead, and IRQ unmasking (read the
<command>hdparm</command> man page for a detailed explanation).
</para>

<para>
Please refer to
"<filename>/proc/ide/<replaceable>[cdrom device]</replaceable>/settings</filename>"
for fine-tuning your CD-ROM.
</para>

<para>
You may tweak the speed of SCSI CD-ROM drives with
<command>sdparm</command>, you need version 1.03 or higher:
<screen>sdparm --command=speed=<replaceable>[speed in kB/s]</replaceable> <replaceable>[cdrom device]</replaceable></screen>
Speed must be specified in kilobytes per second, the drive will
round it as appropriate. Please refer to the sdparm man page for
details.
</para>

<para>
There is also a dedicated tool that works for
<ulink url="http://das.ist.org/~georg/">Plextor SCSI drives</ulink>.
</para>
</sect2>

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<sect2 id="drives_freebsd">
<title>FreeBSD</title>

<para>speed:
<screen>
cdcontrol [-f <replaceable>device</replaceable>] speed <replaceable>[speed]</replaceable>
</screen>
</para>

<para>DMA:
<screen>
sysctl hw.ata.atapi_dma=1
</screen>
</para>

</sect2>

</sect1>


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<sect1 id="dvd">
<title>DVD playback</title>

<para>
For the complete list of available options, please read the man page.
The syntax to play a standard DVD is as follows:
<screen>
mplayer dvd://<replaceable>&lt;track&gt;</replaceable> [-dvd-device <replaceable>&lt;device&gt;</replaceable>]
</screen>
</para>

<para>
Example:
<screen>mplayer dvd://1 -dvd-device /dev/hdc</screen>
</para>

<para>
If you have compiled <application>MPlayer</application> with dvdnav support, the
syntax is the same, except that you need to use dvdnav:// instead of dvd://.
</para>

<para>
The default DVD device is <filename>/dev/dvd</filename>. If your setup
differs, make a symlink or specify the correct device on the command
line with the <option>-dvd-device</option> option.
</para>

<para>
<application>MPlayer</application> uses <systemitem>libdvdread</systemitem> and
<systemitem>libdvdcss</systemitem> for DVD playback and decryption. These two
libraries are contained in the
<application>MPlayer</application> source tree, you do not have
to install them separately. You can also use system-wide versions of the two
libraries, but this solution is not recommended, as it can result in bugs,
library incompatibilities and slower speed.
</para>

<note><para>
In case of DVD decoding problems, try disabling supermount, or any other such
facilities. Some RPC-2 drives may also require setting the region code.
</para></note>

<formalpara>
<title>DVD decryption</title>
<para>
DVD decryption is done by <systemitem>libdvdcss</systemitem>. The method
can be specified through the <envar>DVDCSS_METHOD</envar> environment
variable, see the manual page for details.
</para>
</formalpara>

<sect2 id="region_code">
<title>region code</title>
<para>
DVD drives nowadays come with a nonsensical restriction labeled
<ulink url="http://en.wikipedia.org/wiki/DVD_region_code">region code</ulink>.
This is a scheme to force DVD drives to only accept DVDs produced for one of
the six different regions into which the world was partitioned. How a group
of people can sit around a table, come up with such an idea and expect the
world of the 21st century to bow to their will is beyond anyone's guess.
</para>

<para>
Drives that enforce region settings through software only are also known as
RPC-1 drives, those that do it in hardware as RPC-2. RPC-2 drives allow
changing the region code five times before it remains fixed.
Under Linux you can use the
<ulink url="http://linvdr.org/projects/regionset/">regionset</ulink> tool
to set the region code of your DVD drive.
</para>

<para>
Thankfully, it is possible to convert RPC-2 drives into RPC-1 drives through
a firmware upgrade. Feed the model number of your DVD drive into your favorite
search engine or have a look at the forum and download sections of
<ulink url="http://www.rpc1.org/">"The firmware page"</ulink>.
While the usual caveats for firmware upgrades apply, experience with
getting rid of region code enforcement is generally positive.
</para>
</sect2>

</sect1>


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<sect1 id="vcd">
<title>VCD playback</title>

<para>
For the complete list of available options, please read the man page. The
Syntax for a standard Video CD (VCD) is as follows:
<screen>mplayer vcd://<replaceable>&lt;track&gt;</replaceable> [-cdrom-device <replaceable>&lt;device&gt;</replaceable>]</screen>
Example:
<screen>mplayer vcd://2 -cdrom-device /dev/hdc</screen>
The default VCD device is <filename>/dev/cdrom</filename>. If your setup
differs, make a symlink or specify the correct device on the command line
with the <option>-cdrom-device</option> option.
</para>

<note><para>
At least Plextor and some Toshiba SCSI CD-ROM drives have horrible performance
reading VCDs. This is because the CDROMREADRAW <systemitem>ioctl</systemitem>
is not fully implemented for these drives. If you have some knowledge of SCSI
programming, please <ulink url="../../tech/patches.txt">help us</ulink>
implement generic SCSI support for VCDs.
</para></note>

<para>
In the meantime you can extract data from VCDs with
<ulink url="http://ftp.ntut.edu.tw/ftp/OS/Linux/packages/X/viewers/readvcd/">readvcd</ulink>
and play the resulting file with <application>MPlayer</application>.
</para>

<formalpara>
<title>VCD structure</title>
<para>
A Video CD (VCD) is made up of CD-ROM XA sectors, i.e. CD-ROM mode 2
form 1 and 2 tracks:
<itemizedlist>
<listitem><para>
  The first track is in mode 2 form 2 format which means it uses L2
  error correction. The track contains an ISO-9660 file system with 2048
  bytes/sector. This file system contains VCD metadata information, as
  well as still frames often used in menus. MPEG segments for menus can
  also be stored in this first track, but the MPEGs have to be broken up
  into a series of 150-sector chunks. The ISO-9660 file system may
  contain other files or programs that are not essential for VCD
  operation.
</para></listitem>

<listitem><para>
  The second and remaining tracks are generally raw 2324 bytes/sector
  MPEG (movie) tracks, containing one MPEG PS data packet per
  sector. These are in mode 2 form 1 format, so they store more data per
  sector at the loss of some error correction. It is also legal to have
  CD-DA tracks in a VCD after the first track as well.
  On some operating systems there is some trickery that goes on to make
  these non-ISO-9660 tracks appear in a file system. On other operating
  systems like GNU/Linux this is not the case (yet). Here the MPEG data
  <emphasis role="bold">cannot be mounted</emphasis>. As most movies are
  inside this kind of track, you should try <option>vcd://2</option>
  first.
</para></listitem>

<listitem><para>
  There exist VCD disks without the first track (single track and no file system
  at all). They are still playable, but cannot be mounted.
</para></listitem>

<listitem><para>
  The definition of the Video CD standard is called the
  Philips "White Book" and it is not generally available online as it
  must be purchased from Philips. More detailed information about Video
  CDs can be found in the
  <ulink url="http://www.vcdimager.org/pub/vcdimager/manuals/0.7/vcdimager.html#SEC4">vcdimager documentation</ulink>.
</para></listitem>
</itemizedlist>
</para>
</formalpara>

<formalpara>
<title>About .DAT files</title>
<para>
The ~600 MB file visible on the first track of the mounted VCD is not a real
file! It is a so called ISO gateway, created to allow Windows to handle such
tracks (Windows does not allow raw device access to applications at all).
Under Linux you cannot copy or play such files (they contain garbage). Under
Windows it is possible as its iso9660 driver emulates the raw reading of
tracks in this file. To play a .DAT file you need the kernel driver which can
be found in the Linux version of PowerDVD. It has a modified iso9660 file system
(<filename>vcdfs/isofs-2.4.X.o</filename>) driver, which is able to emulate the
raw tracks through this shadow .DAT file. If you mount the disc using their
driver, you can copy and even play .DAT files with
<application>MPlayer</application>. But it will not
work with the standard iso9660 driver of the Linux kernel! Use
<option>vcd://</option> instead. Alternatives for VCD copying are the
new <ulink url="http://www.elis.rug.ac.be/~ronsse/cdfs/">cdfs</ulink> kernel
driver (not part of the official kernel) that shows CD sessions as image files
and <ulink url="http://cdrdao.sf.net/">cdrdao</ulink>, a bit-by-bit
CD grabbing/copying application.
</para>
</formalpara>
</sect1>
</chapter>
