4.1 CD/DVD drives

Linux documentation excerpt:

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:

• There have been reports of read errors at these high speeds, especially with badly pressed CD-ROMs. Reducing the speed can prevent data loss under these circumstances.
• Many CD-ROM drives are annoyingly loud, a lower speed may reduce the noise.

You can reduce the drive speed with hdparm or a program called setcd. It works like this:

    hdparm -E [speed] [cdrom device]

    setcd -x [speed] [cdrom device]

You can also try

    echo current_speed:4 > /proc/ide/[cdrom device]/settings

but you will need root privileges. The following command may also help:

    echo file_readahead:2000000 > /proc/ide/[cdrom device]/settings

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 hdparm:

    hdparm -d1 -a8 -u1 (cdrom device)

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

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

FreeBSD:

    Speed: cdcontrol [-f device] speed [speed]

    DMA: sysctl hw.ata.atapi_dma=1

4.2 DVD playback

For the complete list of available options, please read the man page.

New-style DVD support (mpdvdkit2)

MPlayer uses libdvdread and libdvdcss for DVD decryption and playback. These two libraries are contained in the libmpdvdkit2/ subdirectory of the MPlayer source tree, you do not have to install them separately. We opted for this solution because we had to fix a libdvdread bug, and apply a patch which adds cracked CSS keys caching support to libdvdcss. This results in a large speed increase because the keys do not have to be cracked every time before playing.

MPlayer can also use system-wide libdvdread and libdvdcss libraries, but this solution is not recommended, as it can result in bugs, library incompatibilities, and slower speed.

DVD Navigation support (dvdnav)

Support for DVD navigation via dvdnav was being worked on, but it was never finished properly and is therefore not recommended!

Old-style DVD support - OPTIONAL

Useful if you want to play encoded VOBs from hard disk. Compile and install libcss 0.0.1 (not newer) for this (If MPlayer fails to detect it, use the -csslib /path/to/libcss.so option). To use it, you need to be root, use a suid root MPlayer binary or let MPlayer call the suid-root fibmap_mplayer wrapper program.

DVD structure

DVD disks use all 2048 b/s sectors with ecc/crc. They usually have an UDF filesystem on a single track, containing various files (small .IFO and .BUK files and big (1GB) .VOB files). They are real files and can be copied/played from a mounted file system of an unencrypted DVD.

The .IFO files contain the movie navigation informations (chapter/title/angle map, language table, etc) and is needed to read and interpret the .VOB content (movie). The .BUK files are backups of them. They use sectors everywhere, so you need to use raw addressing of sectors of the disc to implement DVD navigation. It's also needed to decrypt the content.

The whole old-style DVD support with libcss needs therefore a mounted DVD filesystem and a raw sector-based access to the device. Unfortunately you must be root (under Linux) to get the sector address of a file. You got the following choices:

• Force the user to be root or use a suid-root mplayer binary.
• Let MPlayer call the suid-root fibmap_mplayer wrapper program to access the DVD (used in the old-style DVD playback over libcss).
• Don't use the kernel's filesystem driver at all and re-implement it in userspace. libdvdread 0.9.x and libmpdvdkit does this (New-style DVD support). The kernel udf filesystem drivers isn't needed as they already have their own, built-in udf fs driver. Also the dvd, doesn't needs to be mounted as only the raw sector-based access is used.

Sometimes /dev/dvd can't be read by users, so the libdvdread authors implemented an emulation layer which transfers sector addresses to filenames+offsets, to emulate raw access on the top of a mounted filesystem or even on a hard disk.

libdvdread even accepts the mountpoint instead of the device name for raw access and checks in /proc/mounts to get the device name. It was developed for Solaris, where device names are dynamically allocated.

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

DVD authentication

The authentication and decryption method of the new-style DVD support is done using a patched libdvdcss (see above). The method can be specified over the environment variable DVDCSS_METHOD which can be set to key, disk or title.

If nothing is specified it tries the following methods (default: key, title request):

1. bus key: This key is negotiated during authentication (a long mix of ioctls and various key exchanges, crypto stuff) and is used to encrypt the title and disk keys before sending them over the unprotected bus (to prevent eavesdropping). The bus key is needed to get and predecrypt the crypted disk key.
2. cached key: MPlayer looks for eventually already cracked title keys which are stored in the ~/.mplayer/DVDKeys directory (fast ;).
3. key: If no cached key is available, MPlayer tries to decrypt the disk key with a set of included player keys.
4. disk: If the key method fails (e.g. no included player keys), MPlayer will crack the disk key using a brute force algorithm. This process is CPU intensive and requires 64 MB of memory (16M 32bit entries hash table) to store temporary data. This method should always work (slow).
5. title request: With the disk key MPlayer requests the crypted title keys, which are inside hidden sectors using ioctl(). The region protection of RPC-2 drives is performed in this step and may fail on such drives. If it succeeds, the title keys will be decrypted with the bus and disk key.
6. title: This method is used if the title request failed and does not rely on any key exchange with the DVD drive. It uses a crypto attack to guess the title key directly (by finding a repeating pattern in the decrypted VOB content and guessing that that the plain text for first encrypted bytes are a continuation of that pattern). The method is also known as "known plaintext attack" or "DeCSSPlus". In rare cases this may fail because there is not enough encrypted data on the disk to perform a statistical attack or because the key changes in the middle of a title. On the other hand it is the only way to decrypt a DVD stored on a hard disk or a DVD with the wrong region on an RPC2 drive (slow).

RPC-1 DVD drives only protect region settings over software DVD players. RPC-2 drives have a hardware protection that allows 5 changes only. It might be needed/recommended to upgrade the firmware to RPC-1 if you have a RPC-2 DVD drive. Firmware upgrades can be found here. If there is no firmware upgrade available for your device, use the regionset tool to set the region code of your DVD-drive (under Linux). Warning: You can only set the region 5 times.

4.3 VCD playback

For the complete list of available options, please read the man page. The Syntax for a standard Video CD (VCD) is as followed: mplayer -vcd <track> [-cdrom-device <device>].
Example: mplayer -vcd 2 -cdrom-device /dev/hdc

VCD structure

VCD disks consists of 2 or more track:

• The first track is a few MB 2048 bytes/sector data track, with an iso9660 filesystem, usualy containing win32 VCD player programs and maybe other infos (jpegs, text, etc).
• The second and other tracks are raw 2324 bytes/sector mpeg tracks, without any filesystem but raw mpeg ps data, one packet per sector. they contain the movie(s)... The tracks can't be mounted! It is similar to audio tracks (e.g. You never mounted an audio cd to play it, or did you? No). As most movies are inside track too, you should try -vcd 2 first.
• There exist VCD disks without the first track too (single track and no filesystems at all). They are still playable, but can't be mounted.

About .DAT files:

The ~600 MB file visible on the first track of the mounted vcd isn't a real file! It's a so called iso gateway, created to allow Windows to handle such tracks (Windows doesn't 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 a kernel driver which can be found in the Linux version of PowerDVD. It has a modified iso9660 filesystem (vcdfs/isofs-2.4.X.o) 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 mplayer. But it won't work with the standard iso9660 driver of the kernel! It is recommended to use the -vcd option instead. Alternate options for VCD copy are the new cdfs kernel driver (shows CD sessions as image files) and cdrdao (a bit-to-bit cd grabber/copier application).

The default VCD device is /dev/cdrom. If your setup differs, make a symlink, or specify the correct device on the command line with the -cdrom-device option.