gabriel rosenkoetter on 26 Feb 2009 13:23:41 -0800

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Re: [PLUG] mini-HOWTO: mp3fs

At 2009-02-26 13:23 -0500, Mark M. Hoffman <> wrote:
> Hi Walt, Gabe:
> > On Thu, Feb 26, 2009 at 12:08:14PM -0500, gabriel rosenkoetter wrote:
> > > I actually question the sanity of doing the flac->mp3 processing on
> > > the fly all the time, which entails a non-trivial memory and CPU hit.
> My home file server is not CPU bound.  I guess this is not uncommon.  Also, at
> 128 kb/s encoding, 8 minutes of mp3 is less than 8MB of memory.  No big deal.

No big deal... if only one file within a given mp3fs logical volume
is being read at a time.

> 25 streams of FLAC without mp3fs would be equally hard on the disk, no?

Sure, it would, but that's why I was discussing the CPU and memory
as scaling issues, not the disk I/O.

> Depends on the read/write speed of the device, too.  They're not usually all
> that fast.  I ran the following on a few different mp3fs files:
> 	$ time dd if=blah.mp3 of=/dev/null
> I get about 340 kB/s throughput with an Intel Core2 6600.  I'll have to compare
> that against the speed of my wife's ipod later.

What's your CPU utilization while doing that?

How many of those can you have running at the same time?

(To be clear, these are purely academic questions. I think it sounds
pretty cool, and, although I don't have any quantity of FLACs
floating around, I do have a stack of oggs, and something like this
is a more complete solution than, for example, plugins for iTunes.)

> One downside of this filesystem involves the id3 tags... a lot of software will
> just open every file in a directory and read just enough to process all of the
> tags at once.  It looks like older versions of mp3fs didn't handle this well,
> but the current version does much better.

Huh. Yeah, that's a classic cache miss issue. I wonder if they
solved it in a generalized sort of way (largely "make the cache
bigger") or something smarter, given that they only really care
about a specific target file format.

gabriel rosenkoetter

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