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Re: Double write speed for BD-R without defect management
From: |
Thomas Schmitt |
Subject: |
Re: Double write speed for BD-R without defect management |
Date: |
Wed, 13 Jan 2021 17:27:01 +0100 |
Hi,
carsten.kunze@arcor.de wrote:
> $ dvd+rw-format -ssa=268435456 /dev/sr0
> ...
> - illegal command-line option for this media.
Hm. I see in my experimental copy that i added profile 0x41 (BD-R) to the
test for "ssa"-suitable media before that message:
===========================================================================
@@ -699,9 +704,11 @@ int main (int argc, char *argv[])
force = 0;
}
+/* ts B70205 : added 0x41 as applicable profile */
+
if (((mmc_profile == 0x1A || mmc_profile == 0x2A) && blank)
|| (mmc_profile != 0x1A && compat)
- || (mmc_profile != 0x12 && mmc_profile != 0x43 && ssa) )
+ || (mmc_profile != 0x12 && mmc_profile != 0x43 && mmc_profile != 0x41
&& ssa) )
{ fprintf (stderr,"- illegal command-line option for this media.\n");
goto offer_options;
}
===========================================================================
I don't find matching mails which explain why i had reason to remove this
obstacle.
It is obviously unintended, because around line 420 there is a lengthy
handling of ssa sizes for BD-R:
else if (mmc_profile==0x41) // BD-R
{ unsigned int max,min,cap;
switch (ssa)
{ ...various cases...
> - BD-R can be pre-formatted only once
This message seems to be emitted on any refusal without refering to the
current state of the medium.
> xorriso -outdev /dev/sr0 -speed 2 -as cdrecord -v image.udf
> does write with effective 4.1x speed?
The write speed is finally a decision of the drive. The burn program can
make a proposal by SCSI command SET STREAMING.
xorriso lets libburn send what the user desires.
I did with a BD-RE
xorriso-1.4.6 -scsi_log on -outdev /dev/sr4 -speed 4 \
-as cdrecord -v debian-10.6.0-amd64-netinst.iso 2>&1 | less
and see in the (very lengthy) output
SET STREAMING
b6 00 00 00 00 00 00 00 00 00 1c 00
To drive: 28b
00 00 00 00 00 00 00 00 00 b8 73 ff 00 01 5f 39 00 00 03 e8
00 00 46 3f 00 00 03 e8
The decisive bytes are the last 8:
Write Size = 0x0000463f = 17983
Write Time = 0x000003e8 = 1000
The MMC-5 specs say:
The Write Size field shall be set to the number of kilobytes to be
written per Write Time.
The Write Time field shall indicate the amount of time, in milliseconds,
over that the Write Size is expected to be written.
MMC obeys SI rules. So a "kilobyte" is 1000 bytes and thus the SCSI command
asks for 17,983,000 bytes per second.
BD 1x speed is 4,496,000 bytes per second. Division yields 3.999778.
So my speed wish was computed quite exactly and sent to the drive.
Just the drive did not obey and wrote at 2.0x speed, as expectable with
a BD-RE.
What report do you get with the formatted medium in the drive from this
xorriso run:
xorriso -outdev /dev/sr0 -list_speeds
With an unformatted, partly written BD-R i get:
...
Write speed : 53952k , 12.0xB
Write speed : 44960k , 10.0xB
Write speed : 35968k , 8.0xB
Write speed : 26976k , 6.0xB
Write speed : 17984k , 4.0xB
Write speed L: 17984k , 4.0xB
Write speed H: 53952k , 12.0xB
So i will probably not get fulfilled a wish for less than 4x.
I expect that it will give me the lowest speed from its repertoire.
(Hopefully i will remember tomorrow to try -speed 2 when the next session
is to be written to the medium.)
> My xorriso version is
> xorriso 1.4.6 : RockRidge filesystem manipulator, libburnia project.
> ...
> Version timestamp : 2016.09.16.133001
This is not the freshest version. But such elementary things as speed
setting should not have changed in the last four years.
Have a nice day :)
Thomas