Hi…
“funny thing”… It looks like that only nero recode can write at 12x? I’ve made today 4 dvds for my children to watch (teletubbies from dvb) and had to shrink one because it was a little bit to large:
There is a part (shortend) of the nero recode log:
22:42:59 Prepare recorder [HL-DT-ST DVDRAM GSA-4120B] for write in CUE-sheet-DAO
…
22:42:59 Caching of files started
22:42:59 Cache writing successful.
22:42:59 Caching of files completed
22:42:59 Burn process started at 12x (16.620 KB/s)
22:42:59 Verifying disc position of item 0 (relocatable, disc pos, no patch infos, orig at #0): write at #0
22:42:59 ---- DVD Structure: Physical Format Information (00h) ----
Layer: 0, Address: 0 (0 h), AGID: 0; Length: 2050
Book Type: DVD+R (10), Part Version: 1
Disc Size: 120 mm, Maximum Rate: <not specified> (F h)
Number of Layers: 1, Track Path: Parallel Track Path (PTP), Layer Type: recordable
Linear Density: 0,267 um/bit, Track Density: 0,74 um/track
Starting Physical Sector Number of Data Area: 30000 h (DVD-ROM, DVD-R/-RW, DVD+R/+RW)
End Physical Sector Number of Data Area: 26053F h
End Sector Number in Layer 0: 0 h
Data in Burst Cutting Area (BCA) does not exist
Disc Application Code: 0 / 0 h
Extended Information indicators: 3 h
Disc Manufacturer ID: RICOHJPN
Media type ID: R02
Product revision number: 3
Number of Physical format information bytes in use in ADIP up to byte 63: 56
Media Specific [16…63]:
00 00 03 52 49 43 4F 48 - 4A 50 4E 52 30 32 03 38 …RICOHJPNR02.8
23 54 37 18 00 3E 6E 00 - 70 62 15 15 0B 0B 08 08 #T7…>n.pb…
01 19 1B 0B 0B 0E 0F 01 - 00 00 00 00 00 00 00 00 …
22:42:59 Start write address at LBA 0
DVD high compatibility mode: No
< actual burning process >
22:49:42 <HL-DT-ST DVDRAM GSA-4120B> start writing Lead-Out at LBA 2283616 (22D860h), lenght 0 blocks
22:49:42 all writers idle, stopping conversion
22:49:59 Burn process completed successfully at 12x (16.620 KB/s)
You can see that the burn process lasts from 22:42:59->22:49:59 which is 7 minutes including lead in and out!
Can someone explain why nero recode is so fast and nero burning a DVD video with about 4.1 GB needs > 10 minutes?!? 
Regards,
Gerd