The evident surprise at how quickly FLAC can compress a full CD image
had me worried in case I was completely off in my recollection, so I've
done a quick test on my laptop, which is a Core 2 Duo Intel running at
2GHz with 2GB of ram.  This is quite a similar specification to my
Athlon setup at home.

I started with a WAV image of 47 minutes 20 seconds (489,182 KB), and
then compressed it to FLAC using each of the compression options.  One
caveat here is that I constructed the WAV from Q4 OGGs, so maybe the
lost detail in the OGGs somehow makes for a 'simpler' WAV for the FLAC
algorithm, but I doubt it.

The following shows, for each setting, the time taken, the compressed
file size, the %saving, and KB saved.  The final 2 columns show KB
saved and %saved, compared to compression level -5.

Comp,  Time taken,   Size,     %saving,   KB saved, (KB cf 5), (% cf
5)
0     00:00:17     288536   41.0      200646      -44197      -18.1
1     00:00:16     259350   47.0      229832      -15011      -6.1
2     00:00:18     258221   47.2      230961      -13882      -5.7
3     00:00:21     275245   43.7      213937      -30906      -12.6
4     00:00:25     245664   49.8      243518       -1325      -0.5
5     00:00:33     244339   50.1      244843           0      0.0
6     00:00:36     244312   50.1      244870          27      0.0
7     00:01:10     243216   50.3      245966        1123      0.5
8     00:01:35     240902   50.8      248280        3437      1.4

(sorry - the spaces in my table seem to be removed by the forum
software, but you get the gist!)

So it seems my memory was about right - Level 5 was finished in 33
seconds.  Level 8 took 3 times as long, and only saved 1.4% compared to
level 5.  Something odd seems to have happened at level 3, but it looks
as though level 4 might actually be the optimum - only 0.5% bigger than
level 5, but about 25% faster.

Of course these results will be different for other CDs - in particular
I want to see if the OGG starting point has made any difference.


-- 
chill
------------------------------------------------------------------------
chill's Profile: http://forums.slimdevices.com/member.php?userid=10839
View this thread: http://forums.slimdevices.com/showthread.php?t=34156

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