Messages in this thread | | | Date | Tue, 28 Feb 2006 13:44:31 +1300 | From | Sam Vilain <> | Subject | Re: CD writing in future Linux (stirring up a hornets' nest) |
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D. Hazelton wrote: >>>This value is also reported by the drive. I don't know about DVD drives, >>>but for CD drives it is a multiplier. 1x == 256K/sec transfer off the >>>disc [...] >>For CDs, 1x is actually 150 KByte/sec. > Well, I've been known to be wrong before, and this number was more based on > the fact that I once measured a sustained transfer rate of 1M/sec on a 4x > CDROM
Think about audio. Single speed = 75 frames of 2352 bytes per second, or 176kB/s. However with data tracks you only get 2k per frame/sector, so that works out to be 153kB/s.
Due to the CLV nature of CD-ROMs you may find the drive is faster reading some parts of the disc than others.
>>According to WikiPedia, the DVD speed rating is almost 9 times that of >>CD speeds. I.e., 1x DVD is about 1.32 MByte/sec. > This was based on DVDx16 == CDx48 - I'm guessing someone is doing some monkey > work if a DVD is 9x a CD and a 16x DVD can't hit that mystical 52x of my > favorite CDRW drive in pure CD read mode.
You can do a similar calculation with DVDs. While I can't find a reference for the maximum DVD total bitrate of ~10Mbit/s, this at 1.25 MByte/s this roughly agrees with the 1.32 quoted.
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