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Topic: FLAC v1.4.x Performance Tests (Read 22302 times) previous topic - next topic
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Re: FLAC v1.4.x Performance Tests

Reply #275
30-ish GB of decoded HDCD rips. Yeah I know I shouldn't have made that irreversible mistake fifteen years ago, but here we are.
So these are effectively 17-ish bits in 24 bit container - 95 percent of the tracks have a peak less than .8 scanned with oversampling.

* Why test these? Just to see whether there are any surprises with slightly unusual signals.
* Were there any? Not really. -4 isn't particularly good; I have earlier on questioned whether -5 is really much of an improvement over -4, but here it is. Anyway, that question has probably not made any great impact, I mean who uses -4?

What I did was to re-encode FLAC files (with overwrite) on an SSD. That is why I quote the times per encoded gigabyte. "142" means reference FLAC 1.4.2 Win64, 134 means 1.3.4 Win64, both Xiph builds.
Numbers then. Size relative to 1.4.2 -5, then setting, then comment with time taken. Sizes are file sizes, with tags and default padding.

+1.574%   142-4   ~25 sec per GB (encoded GB).
+0.119%   134-5 
ref.point   142-5   ~30 sec/GB. 31 808 619 711 bytes
-0.255%   134-7 
-0.306%   134-8 
-0.347%   142-7  ~37 sec/GB.
-0.397%   142-8  ~1 minute/GB.
-0.399%   134-8p
-0.412%   142-8e   ~3 minutes/GB.
-0.428%   142-"all the sevens but no p" (see below) - also ~3 minutes/GB.
-0.461%   134-8pe ~20 min/GB.
-0.480%   142-8p 2min40s/GB.
-0.507%   142-8pe Also in the ~20min/GB ballpark
-0.514%   142-"-p all the sevens", about the same time as -8pe

That "all the sevens" - and why not "8"? It is not because it is good! It is because I wanted to come up with a command that was easy to remember, takes about as much time as "-e" and outcompresses -e. Supporting the claim that "-e" should not be used on typical music with normal resolutions: if you are even willing to wait for -e, then there are better things around. (It is known that -e still has something for it on higher sampling rates, potentially.)
The actual option line is -7r7 -A "flattop;gauss(7e-2);tukey(7e-1);subdivide_tukey(7)" with an additional "-p" for the last line. And a -f to overwrite, but that goes for everything.
For those who ask "why -7 and not -8"? It wouldn't make any difference, -8 is -7 with a different (and heavier) "-A", and the moment I write "-A" here I override that by specifying yet a different (and heavier!!) -A.

Did you really type "flatopp"?
Damn, only one way to find out, and that is not done in two minutes ...
Here I made sure to get it right!  O:)

But anyway, bottom line is what we knew, 1.4.x improves, and -e does not deliver at these resolutions. -p is nearly as expensive, but much better