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Subject: Re: H340 HDD spinning constantly in USB mode? (and general disk spin time question)

Re: H340 HDD spinning constantly in USB mode? (and general disk spin time question)

From: Mike Hodson <mystica_at_gmail.com>
Date: Tue, 25 Nov 2008 17:33:38 -0700

On Tue, Nov 25, 2008 at 3:53 PM, Andreas Stemmer <groovingandi_at_gmx.de> wrote:

> Yes, you could describe it like that. I have to check the actual manual
> entry for the feature. I once had a portable cd player that had this
> feature, that's why it was clear for me what it meant.

I also have had CD players with such a feature, however I feel they
work closer to how I thought...

At least with Sonys, you had a choice of 0 anti-skip, 15s anti-skip
and 1m anti-skip. This to me was how much music would be put into the
buffer, whereas the refill of the buffer was a constantly spinning
disc. The disc would spin about 2x speed to keep the buffer full, and
be able to refill if it ever ran out. To me this meant If I selected
1 minute, then I know I would have 1 minute of audio stored in ram
should I be jiggling the player enough to make the optical head have
reading issues.

I was guessing that was how the Rockbox buffer worked; that I needed
to tell it how much audio to put into memory.

I felt that if I didn't set a high enough amount of audio in the
buffer to fill up the player's RAM, then the extra 'unused RAM' would
just go to waste or the hdd would waste power having to spin up/down
more often because, so I thought, "only 5 seconds would be stored in
ram" or something to that effect. I literally thought that the 5
second buffer would keep the hdd spinning all the time, because no
more than 5 seconds would be buffered. (If i had a 1 minute buffer, I
envisioned spin-ups once a minute)

The whole "player fills amount of free memory as far as it can, and
drains to Anti-skip Buffer Amount of time before refilling" concept
was apparently lost on me :\

The confusion point for me seems to be that CDs are always refilling,
always spinning; you just tell it how much audio you want to be stored
in memory should the disk stop reading. Rockbox only spins the drive
to fill its cache insanely fast and then drains to the buffer amount
while the hdd is powered down. It is in a mostly-constant state of
not-reading. I thought that this state of non-reading is what the
Anti-Skip Buffer length controlled.

The only chance Rockbox has to 'skip' is during the memory refill
period, so it makes sense that your 'buffer' need only be long enough
to prevent some massive unexpected shaking of the player from causing
the hdd to not read for all of 15 seconds or so, before it shuts off
again.

Mike
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Received on 2008-11-26


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