#Cache Testing
Reese,
My command line for CD Speedway is:
CDSPEED BP:H:\ C:8192 S:OFF
and it's the last line in my AUTOEXEC.BAT
Drive H: is an 8mb RAM drive. I've also experimented with an 8mb HD cache
(my HD is ESDI with 18ms access time) without any significant difference in
performmance, either from DOS or from Windows. Other factors I've played
around with are number of DOS buffers (2-30), number of buffers for the
CD-Rom driver (2-32), number of buffers for MSCDEX (0-128). For these last
two, allocating more than 4 buffers each doesn't improve performance by any
noticeable amount.
I pretty much agree with your position on read-ahead caching. When playing
motion video stuff from a CD-Rom drive at a 150kb/sec DTR, there's not
going to be a chance for the reader to get ahead of the display, unless the
movie is in some highly compressed format which can be decompressed very
rapidly after getting it into RAM. Some of the fractal compression and MPEG
demos I've seen show some promise of being able to do this.
Since I can get fairly smooth playback of Mammals clips (which are in
320×200 resolution) without even using a cache at all, I assume that the
DFF format of the clips is some sort of compression scheme, perhaps where
only the change from one frame to another is being recorded. The clips on
the Aris MediaClips discs use tiny 160×100 frames (they have a .CAV
extension, whatever that means) and are unwatchable with caching. Speedway
or Speedcache+ makes a big difference here, with Speedcache+ having the
edge. Any suggestions for improvement would be most welcome. I mailed the
registration card yesterday and look forward to upgrades for Speedway.
Regards,
Tom