Re: DVD Burning speed

["Thomas Schmitt" <scdbackup@gmx.net>]

Hi,

deloptes wrote:
> What does determine the DVD burning speed? Is it the DVD or the burner or
> both?

The drive decides according to its assessment of the medium and the
speed wish issued by the burn program.

The drive announces a list of possible speeds, depending on the medium.
E.g.:

  $ xorriso -outdev /dev/sr0 -list_speeds
  ...
  Media current: DVD+R/DL
  Media status : is blank
  Media summary: 0 sessions, 0 data blocks, 0 data, 8152m free
  Read speed   :  11079k ,  8.0xD
  Read speed   :   4568k ,  3.3xD
  Read speed L :   4568k ,  3.3xD
  Read speed H :  11079k ,  8.0xD
  Write speed  :   5540k ,  4.0xD
  Write speed  :   3324k ,  2.4xD
  Write speed L:   3324k ,  2.4xD
  Write speed H:   5540k ,  4.0xD

So this drive offers write speed 4.0x and 2.4x, with 1x being 1385 KB/s.
Other drives or media may offer more than just two write speeds.

  Media current: DVD-R sequential recording
  ...
  Write speed  :  22160k , 16.0xD
  Write speed  :  16620k , 12.0xD
  Write speed  :  11080k ,  8.0xD
  Write speed L:  11080k ,  8.0xD
  Write speed H:  22160k , 16.0xD

Those speeds are nominal. I.e. with several media types the drive
will start slower and will slowly accelerate until it reaches the
nominal speed at the outer rim of the medium.


> How can I write DL dvd at 1x speed?

The only certain influence from outside the drive is the data bandwith.
If your program only sends 1385 KB/s to the drive, then it will not be
able to surpass effective speed of 1x.

But this might just mean that the drive waits a few hundred milliseconds
until its buffer is sufficiently full, and then writes at its own chosen
speed until its buffer is empty again.


> I do not have option 1x - it gives me minimum 3x. Why is this so

If it is Brasero, K3B, or Xfburn, then the offer stems from SCSI
commands which inquire above speed list. (Either directly sent from
the burn program or indirectly triggered by asking libburn which then
asks the drive.)

The offer "3x" is somewhat unusual for DVD+R DL. I only know this from
DVD-RAM media. It might indeed stem from a 2.4x list entry.

----------------------------------------------------------------------

In general i think that the traditional advise to burn at 1x speed is
an urban legend caused by drives at the brink of failure.

Low speed makes low noise. So with with the fast spinning media BD-R,
DVD-R, DVD+R, or CD-R it might be desirable to ask the drive for the
lowest speed available. A speed wish of "1x" should tell it to try its
best to be slow and silent.


Have a nice day :)

Thomas