18.7 Creating and Using Optical Media (DVDs)

18.7.1 Introduction

Compared to the CD, the DVD is the next generation of optical media storage technology. The DVD can hold more data than any CD and is nowadays the standard for video publishing.

Five physical recordable formats can be defined for what we will call a recordable DVD:

• DVD-R: This was the first DVD recordable format available. The DVD-R standard is defined by the DVD Forum. This format is write once.

• DVD-RW: This is the rewritable version of the DVD-R standard. A DVD-RW can be rewritten about 1000 times.

• DVD-RAM: This is also a rewritable format supported by the DVD Forum. A DVD-RAM can be seen as a removable hard drive. However, this media is not compatible with most DVD-ROM drives and DVD-Video players; only a few DVD writers support the DVD-RAM format. Read the Section 18.7.9 for more information on DVD-RAM use.

• DVD+RW: This is a rewritable format defined by the DVD+RW Alliance. A DVD+RW can be rewritten about 1000 times.

• DVD+R: This format is the write once variation of the DVD+RW format.

A single layer recordable DVD can hold up to 4,700,000,000 bytes which is actually 4.38 GB or 4485 MB (1 kilobyte is 1024 bytes).

18.7.2 Configuration

The program growisofs(1) will be used to perform DVD recording. This command is part of the dvd+rw-tools utilities (sysutils/dvd+rw-tools). The dvd+rw-tools support all DVD media types.

These tools use the SCSI subsystem to access to the devices, therefore the ATAPI/CAM support must be added to your kernel. If your burner uses the USB interface this addition is useless, and you should read the Section 18.5 for more details on USB devices configuration.

You also have to enable DMA access for ATAPI devices, this can be done in adding the following line to the /boot/loader.conf file:

hw.ata.atapi_dma="1"

Before attempting to use the dvd+rw-tools you should consult the dvd+rw-tools' hardware compatibility notes for any information related to your DVD burner.

18.7.3 Burning Data DVDs

The growisofs(1) command is a frontend to mkisofs, it will invoke mkisofs(8) to create the file system layout and will perform the write on the DVD. This means you do not need to create an image of the data before the burning process.

To burn onto a DVD+R or a DVD-R the data from the /path/to/data directory, use the following command:

# growisofs -dvd-compat -Z /dev/cd0 -J -R /path/to/data

The options -J -R are passed to mkisofs(8) for the file system creation (in this case: an ISO 9660 file system with Joliet and Rock Ridge extensions), consult the mkisofs(8) manual page for more details.

The option -Z is used for the initial session recording in any case: multiple sessions or not. The DVD device, /dev/cd0, must be changed according to your configuration. The -dvd-compat parameter will close the disk, the recording will be unappendable. In return this should provide better media compatibility with DVD-ROM drives.

It is also possible to burn a pre-mastered image, for example to burn the image imagefile.iso, we will run:

# growisofs -dvd-compat -Z /dev/cd0=imagefile.iso

The write speed should be detected and automatically set according to the media and the drive being used. If you want to force the write speed, use the -speed= parameter. For more information, read the growisofs(1) manual page.

18.7.4 Burning a DVD-Video

A DVD-Video is a specific file layout based on ISO 9660 and the micro-UDF (M-UDF) specifications. The DVD-Video also presents a specific data structure hierarchy, it is the reason why you need a particular program such as multimedia/dvdauthor to author the DVD.

If you already have an image of the DVD-Video file system, just burn it in the same way as for any image, see the previous section for an example. If you have made the DVD authoring and the result is in, for example, the directory /path/to/video, the following command should be used to burn the DVD-Video:

# growisofs -Z /dev/cd0 -dvd-video /path/to/video

The -dvd-video option will be passed down to mkisofs(8) and will instruct it to create a DVD-Video file system layout. Beside this, the -dvd-video option implies -dvd-compat growisofs(1) option.

18.7.5 Using a DVD+RW

Unlike CD-RW, a virgin DVD+RW needs to be formatted before first use. The growisofs(1) program will take care of it automatically whenever appropriate, which is the recommended way. However you can use the dvd+rw-format command to format the DVD+RW:

# dvd+rw-format /dev/cd0

You need to perform this operation just once, keep in mind that only virgin DVD+RW medias need to be formatted. Then you can burn the DVD+RW in the way seen in previous sections.

If you want to burn new data (burn a totally new file system not append some data) onto a DVD+RW, you do not need to blank it, you just have to write over the previous recording (in performing a new initial session), like this:

# growisofs -Z /dev/cd0 -J -R /path/to/newdata

DVD+RW format offers the possibility to easily append data to a previous recording. The operation consists in merging a new session to the existing one, it is not multisession writing, growisofs(1) will grow the ISO 9660 file system present on the media.

For example, if we want to append data to our previous DVD+RW, we have to use the following:

# growisofs -M /dev/cd0 -J -R /path/to/nextdata

The same mkisofs(8) options we used to burn the initial session should be used during next writes.

If for any reason you really want to blank the media, do the following:

# growisofs -Z /dev/cd0=/dev/zero

18.7.6 Using a DVD-RW

A DVD-RW accepts two disc formats: the incremental sequential one and the restricted overwrite. By default DVD-RW discs are in sequential format.

A virgin DVD-RW can be directly written without the need of a formatting operation, however a non-virgin DVD-RW in sequential format needs to be blanked before to be able to write a new initial session.

To blank a DVD-RW in sequential mode, run:

# dvd+rw-format -blank=full /dev/cd0

To write data on a sequential DVD-RW, use the same instructions as for the other DVD formats:

# growisofs -Z /dev/cd0 -J -R /path/to/data

If you want to append some data to your previous recording, you will have to use the growisofs(1) -M option. However, if you perform data addition on a DVD-RW in incremental sequential mode, a new session will be created on the disc and the result will be a multi-session disc.

A DVD-RW in restricted overwrite format does not need to be blanked before a new initial session, you just have to overwrite the disc with the -Z option, this is similar to the DVD+RW case. It is also possible to grow an existing ISO 9660 file system written on the disc in a same way as for a DVD+RW with the -M option. The result will be a one-session DVD.

To put a DVD-RW in the restricted overwrite format, the following command must be used:

# dvd+rw-format /dev/cd0

To change back to the sequential format use:

# dvd+rw-format -blank=full /dev/cd0

18.7.7 Multisession

Very few DVD-ROM drives support multisession DVDs, they will most of time, hopefully, only read the first session. DVD+R, DVD-R and DVD-RW in sequential format can accept multiple sessions, the notion of multiple sessions does not exist for the DVD+RW and the DVD-RW restricted overwrite formats.

Using the following command after an initial (non-closed) session on a DVD+R, DVD-R, or DVD-RW in sequential format, will add a new session to the disc:

# growisofs -M /dev/cd0 -J -R /path/to/nextdata

Using this command line with a DVD+RW or a DVD-RW in restricted overwrite mode, will append data in merging the new session to the existing one. The result will be a single-session disc. This is the way used to add data after an initial write on these medias.

18.7.8 For More Information

To obtain more information about a DVD, the dvd+rw-mediainfo /dev/cd0 command can be ran with the disc in the drive.

More information about the dvd+rw-tools can be found in the growisofs(1) manual page, on the dvd+rw-tools web site and in the cdwrite mailing list archives.

18.7.9 Using a DVD-RAM

hw.ata.atapi_dma="1"

# dd if=/dev/zero of=/dev/acd0 bs=2k count=1
# bsdlabel -Bw acd0
# newfs /dev/acd0

# mount /dev/acd0 /mnt