K3Bを使ってCD-ROMを焼こうとしたときに71MBを書き込んだ後、バーナー速度が10倍から0.12倍に遅くなりました。そのため、142MB Live CDを焼くのに1時間以上かかります。なぜこれが起こるのですか？
CD-ROM書き込みツールはOPTIARC DVD RW AD-5690H（ファームウェアバージョン4AH5）で、K3Bで使用されるCD-ROM書き込みツールはcdrecord 3.0です。
更新：最後の書き込み操作のログは次のとおりです。
Devices
-----------------------
OPTIARC DVD RW AD-5690H 4AH5 (/dev/sr0, Cd-r, CD-RW, Cd-rom, Dvd-rom, DVD-R, DVD-RW, DVD-R DL, DVD+R, DVD+RW, DVD+R DL) [Dvd-rom, DVD-R sekventiel, DVD-R dobbeltlag, sekvensielt, DVD-R dobbeltlag og hop-mulighed, DVD-RW begrænset overbrænding, DVD-RW sekventiel, DVD+RW, DVD+R, DVD+R dobbeltlag, Cd-rom, Cd-r, CD-RW] [SAO, TAO, RAW, SAO/R96R, RAW/R16, RAW/R96P, RAW/R96R, Begrænset overbrænding, Lag-hop] [%7]
System
-----------------------
K3b Version: 2.0.2
KDE Version: 4.8.4 (4.8.4)
QT Version: 4.8.2
Kernel: 3.13.6
Used versions
-----------------------
cdrecord: 3.0
cdrecord
-----------------------
scsidev: '/dev/sr0'
devname: '/dev/sr0'
scsibus: -2 target: -2 lun: -2
Warning: Open by 'devname' is unintentional and not supported.
Linux sg driver version: 3.5.27
SCSI buffer size: 64512
/opt/schily/bin/cdrecord: Warning: Cannot read drive buffer.
/opt/schily/bin/cdrecord: Warning: The DMA speed test has been skipped.
Cdrecord-ProDVD-ProBD-Clone 3.00 (x86_64-unknown-linux-gnu) Copyright (C) 1995-2010 J�rg Schilling
TOC Type: 1 = CD-ROM
Using libscg version 'schily-0.9'.
Driveropts: 'burnfree'
atapi: 1
Device type : Removable CD-ROM
Version : 5
Response Format: 2
Capabilities :
Vendor_info : 'OPTIARC '
Identifikation : 'DVD RW AD-5690H '
Revision : '4AH5'
Device seems to be: Generic mmc2 DVD-R/DVD-RW/DVD-RAM.
Current: CD-R
Profile: DVD+R/DL
Profile: DVD+R
Profile: DVD+RW
Profile: DVD-R/DL layer jump recording
Profile: DVD-R/DL sequential recording
Profile: DVD-RW sequential recording
Profile: DVD-RW restricted overwrite
Profile: DVD-R sequential recording
Profile: DVD-ROM
Profile: CD-RW
Profile: CD-R (current)
Profile: CD-ROM (current)
Using generic SCSI-3/mmc CD-R/CD-RW driver (mmc_cdr).
Driver flags : MMC-3 SWABAUDIO BURNFREE
Supported modes: TAO PACKET SAO SAO/R96R RAW/R16 RAW/R96P RAW/R96R
Drive buf size : 1273856 = 1244 KB
FIFO size : 4194304 = 4096 KB
Track 01: data 142 MB
Total size: 163 MB (16:09.38) = 72704 sectors
Lout start: 163 MB (16:11/29) = 72704 sectors
Current Secsize: 2048
ATIP info from disk:
Indicated writing power: 6
Disk Is not unrestricted
Disk Is not erasable
Disk sub type: Medium Type C, low Beta category (C-) (6)
ATIP start of lead in: -11231 (97:32/19)
ATIP start of lead out: 359846 (79:59/71)
Disk type: Short strategy type (Phthalocyanine or similar)
Manuf. index: 27
Manufacturer: Prodisc Technology Inc.
Capacity Blklen/Sparesz. Format-type Type
0 2048 0x00 No Media Present or Unknown Capacity
Blocks total: 359846 Blocks current: 359846 Blocks remaining: 287142
Starting to write CD/DVD/BD at speed 24 in real SAO mode for single session.
Last chance to quit, starting real write in 3 seconds.
2 seconds.
1 seconds.
0 seconds. Operation starts.
Waiting for reader process to fill input buffer ... input buffer ready.
BURN-Free is OFF.
Turning BURN-Free on
Performing OPC...
Sending CUE sheet...
/opt/schily/bin/cdrecord: WARNING: Drive returns wrong startsec (0) using -150
Writing pregap for track 1 at -150
Starting new track at sector: 0
Track 01: 0 of 142 MB written.
Track 01: 1 of 142 MB written (fifo 100%) 0.5x.
Track 01: 2 of 142 MB written (fifo 100%) [buf 100%] 1.6x.
Track 01: 3 of 142 MB written (fifo 100%) [buf 100%] 11.9x.
Track 01: 4 of 142 MB written (fifo 100%) [buf 100%] 11.6x.
Track 01: 5 of 142 MB written (fifo 100%) [buf 100%] 12.0x.
Track 01: 6 of 142 MB written (fifo 100%) [buf 100%] 11.6x.
Track 01: 7 of 142 MB written (fifo 100%) [buf 100%] 12.0x.
Track 01: 8 of 142 MB written (fifo 100%) [buf 100%] 11.7x.
Track 01: 9 of 142 MB written (fifo 100%) [buf 100%] 12.1x.
Track 01: 10 of 142 MB written (fifo 100%) [buf 100%] 11.7x.
Track 01: 11 of 142 MB written (fifo 100%) [buf 100%] 12.1x.
Track 01: 12 of 142 MB written (fifo 100%) [buf 100%] 11.8x.
Track 01: 13 of 142 MB written (fifo 100%) [buf 100%] 12.2x.
Track 01: 14 of 142 MB written (fifo 100%) [buf 100%] 11.8x.
Track 01: 15 of 142 MB written (fifo 100%) [buf 100%] 12.2x.
Track 01: 16 of 142 MB written (fifo 100%) [buf 100%] 11.9x.
Track 01: 17 of 142 MB written (fifo 100%) [buf 100%] 12.3x.
Track 01: 18 of 142 MB written (fifo 100%) [buf 100%] 11.9x.
Track 01: 19 of 142 MB written (fifo 100%) [buf 100%] 12.3x.
Track 01: 20 of 142 MB written (fifo 100%) [buf 100%] 12.0x.
Track 01: 21 of 142 MB written (fifo 100%) [buf 100%] 12.4x.
Track 01: 22 of 142 MB written (fifo 100%) [buf 100%] 12.0x.
Track 01: 23 of 142 MB written (fifo 100%) [buf 100%] 12.4x.
Track 01: 24 of 142 MB written (fifo 100%) [buf 100%] 12.0x.
Track 01: 25 of 142 MB written (fifo 100%) [buf 100%] 12.5x.
Track 01: 26 of 142 MB written (fifo 100%) [buf 100%] 12.1x.
Track 01: 27 of 142 MB written (fifo 100%) [buf 100%] 12.5x.
Track 01: 28 of 142 MB written (fifo 100%) [buf 100%] 12.1x.
Track 01: 29 of 142 MB written (fifo 100%) [buf 100%] 12.5x.
Track 01: 30 of 142 MB written (fifo 100%) [buf 100%] 12.2x.
Track 01: 31 of 142 MB written (fifo 100%) [buf 100%] 12.6x.
Track 01: 32 of 142 MB written (fifo 100%) [buf 100%] 12.2x.
Track 01: 33 of 142 MB written (fifo 100%) [buf 100%] 12.6x.
Track 01: 34 of 142 MB written (fifo 100%) [buf 100%] 13.0x.
Track 01: 35 of 142 MB written (fifo 100%) [buf 100%] 12.6x.
Track 01: 36 of 142 MB written (fifo 100%) [buf 100%] 13.1x.
Track 01: 37 of 142 MB written (fifo 100%) [buf 100%] 12.7x.
Track 01: 38 of 142 MB written (fifo 100%) [buf 100%] 13.1x.
Track 01: 39 of 142 MB written (fifo 100%) [buf 100%] 12.7x.
Track 01: 40 of 142 MB written (fifo 100%) [buf 100%] 13.2x.
Track 01: 41 of 142 MB written (fifo 100%) [buf 100%] 12.8x.
Track 01: 42 of 142 MB written (fifo 100%) [buf 100%] 13.2x.
Track 01: 43 of 142 MB written (fifo 100%) [buf 100%] 12.8x.
Track 01: 44 of 142 MB written (fifo 100%) [buf 100%] 13.2x.
Track 01: 45 of 142 MB written (fifo 100%) [buf 100%] 12.8x.
Track 01: 46 of 142 MB written (fifo 100%) [buf 100%] 13.3x.
Track 01: 47 of 142 MB written (fifo 100%) [buf 100%] 12.9x.
Track 01: 48 of 142 MB written (fifo 100%) [buf 100%] 13.3x.
Track 01: 49 of 142 MB written (fifo 100%) [buf 100%] 12.9x.
Track 01: 50 of 142 MB written (fifo 100%) [buf 100%] 13.4x.
Track 01: 51 of 142 MB written (fifo 100%) [buf 100%] 13.0x.
Track 01: 52 of 142 MB written (fifo 100%) [buf 100%] 13.4x.
Track 01: 53 of 142 MB written (fifo 100%) [buf 100%] 13.0x.
Track 01: 54 of 142 MB written (fifo 100%) [buf 100%] 13.4x.
Track 01: 55 of 142 MB written (fifo 100%) [buf 100%] 13.0x.
Track 01: 56 of 142 MB written (fifo 100%) [buf 100%] 13.5x.
Track 01: 57 of 142 MB written (fifo 100%) [buf 100%] 13.1x.
Track 01: 58 of 142 MB written (fifo 100%) [buf 100%] 13.5x.
Track 01: 59 of 142 MB written (fifo 100%) [buf 100%] 13.1x.
Track 01: 60 of 142 MB written (fifo 100%) [buf 100%] 13.5x.
Track 01: 61 of 142 MB written (fifo 100%) [buf 100%] 13.2x.
Track 01: 62 of 142 MB written (fifo 100%) [buf 100%] 13.6x.
Track 01: 63 of 142 MB written (fifo 100%) [buf 100%] 13.2x.
Track 01: 64 of 142 MB written (fifo 100%) [buf 100%] 13.6x.
Track 01: 65 of 142 MB written (fifo 100%) [buf 100%] 14.0x.
Track 01: 66 of 142 MB written (fifo 100%) [buf 100%] 13.6x.
Track 01: 67 of 142 MB written (fifo 100%) [buf 100%] 14.1x.
Track 01: 68 of 142 MB written (fifo 100%) [buf 100%] 13.7x.
Track 01: 69 of 142 MB written (fifo 100%) [buf 100%] 14.1x.
Track 01: 70 of 142 MB written (fifo 100%) [buf 100%] 13.7x.
Track 01: 71 of 142 MB written (fifo 100%) [buf 100%] 14.2x.
Track 01: 72 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 73 of 142 MB written (fifo 100%) [buf 100%] 0.1x.
Track 01: 74 of 142 MB written (fifo 100%) [buf 100%] 0.1x.
Track 01: 75 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 76 of 142 MB written (fifo 100%) [buf 100%] 0.1x.
Track 01: 77 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 78 of 142 MB written (fifo 100%) [buf 100%] 0.1x.
Track 01: 79 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 80 of 142 MB written (fifo 100%) [buf 100%] 0.1x.
Track 01: 81 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 82 of 142 MB written (fifo 100%) [buf 100%] 0.1x.
Track 01: 83 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 84 of 142 MB written (fifo 100%) [buf 100%] 0.1x.
Track 01: 85 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 86 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 87 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 88 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 89 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 90 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 91 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 92 of 142 MB written (fifo 100%) [buf 100%] 0.1x.
Track 01: 93 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 94 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 95 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 96 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 97 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 98 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 99 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 100 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 101 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 102 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 103 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 104 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 105 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 106 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 107 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 108 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 109 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 110 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 111 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 112 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 113 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 114 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 115 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 116 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 117 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 118 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 119 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 120 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 121 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 122 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 123 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 124 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 125 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 126 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 127 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 128 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 129 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 130 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 131 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 132 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 133 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 134 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 135 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 136 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 137 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 138 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 139 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 140 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 141 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: 142 of 142 MB written (fifo 100%) [buf 100%] 0.2x.
Track 01: Total bytes read/written: 148897792/148897792 (72704 sectors).
Writing time: 3133.095s
Average write speed 0.3x.
Min drive buffer fill was 100%
Fixating...
Fixating time: 17.058s
/opt/schily/bin/cdrecord: fifo had 2346 puts and 2346 gets.
/opt/schily/bin/cdrecord: fifo was 0 times empty and 2267 times full, min fill was 84%.
BURN-Free was never needed.
cdrecord command:
-----------------------
/opt/schily/bin/cdrecord -v gracetime=2 dev=/dev/sr0 speed=24 -sao driveropts=burnfree -data -tsize=72704s -