[Flac] FLAC: general question

[Brian Willoughby]

Harry,

Another thing to consider is the balance between CPU efficiency and  
disk speed.  On some of my systems, decoding a FLAC file to AIFF (or  
WAV) uses 100% of the CPU.  That's because the drive is faster than  
the CPU, so the CPU is constantly working.  Moving to a 4-processor  
system, I can run 4 FLAC decodes at the same time.  At first, that  
would not use 400% (100% of all 4 CPUs) because the disk was not fast  
enough to read 4 files and write 4 files at once.  But as soon as I  
upgraded to a faster drive on a faster bus, I am back to 400% CPU  
usage when decoding.

I use FLAC to back up original multi-track recordings.  Then I burn  
the FLAC files to CD-R or DVD-R.  Whenever a client needs the  
originals for a mixing session, I have to pull all the FLAC files  
from optical media and decode them, since nearly all mixing software  
uses AIFF (even the ones that allow FLAC will convert the files from  
FLAC to something else on disk).  In order to respond to the client  
as fast as possible, I want to decode the FLAC files as fast as  
possible, so I have experimented with faster machines and faster drives.

In other words, I'm not sure that you can make any solid conclusions  
from a comparison table, even if you could find one, because it would  
always be possible to recompile flac, or upgrade the CPU, or upgrade  
the disk, or add additional disks to spread the load.  There is no  
single answer to your question.

Brian Willoughby
Sound Consulting


On Jul 25, 2007, at 11:21, Harry Sack wrote:

Maybe somebody knows some comparison tables with some measured values  
like the ones available for encoding times?
(so now I'm looking for the decoding CPU power loads)

thx