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Topic: higher compression ratios in FLAC (Read 21015 times) previous topic - next topic
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Re: higher compression ratios in FLAC

Reply #50 –
FLACout - http://advsys.net/ken/utils.htm
Is a flac optimizer that can squeeze out a bit more efficiency at the cost of a lot of time
Sven Bent - Denmark

Re: higher compression ratios in FLAC

Reply #51 –
Quote from: sven_Bent on
FLACout - http://advsys.net/ken/utils.htm
Is a flac optimizer that can squeeze out a bit more efficiency at the cost of a lot of time

It didn't really work the last time we tried https://hydrogenaud.io/index.php/topic,106129.msg868366.html#msg868366
Is troll-adiposity coming from feederism?
With 24bit music you can listen to silence much louder!

Re: higher compression ratios in FLAC

Reply #52 –
About FLAC optimization -- I played with that for a while to see what could be done.  I experimented with the apodization functions available -- and could usually see some improvement by adding some functions, and using some of the complete search type things..  If I got more than a few percent better on a normal file, I was happy that there was some progress.
For day-to-day, where it isn't practical to take real-time to compress a file, the default -8 does pretty good.  Maybe a few percent can be had, at a cost of 10X more more the amount of compression time.

I seem to remember that adding blackman_harris_4term_92dB & kaiser_bessel sometimes helps (btw, I use those window functions on my software DolbyA decoder for certain subtile characteristics -- but those characteristics might not be why those apodization functions seemed to have helped.)

John

Re: higher compression ratios in FLAC

Reply #53 –
If I remember correctly, the current -8 also came about after experimenting with some apodization functions, and finding a pretty good combination?

Re: higher compression ratios in FLAC

Reply #54 –
TLDR;

If you have files with reduced bitdepth like Lossywav processed files you cannot achieve smaller files with recompression unless you use the right blocksize. For CD recordings this is 512. Lossywav files need some special attention.

Re: higher compression ratios in FLAC

Reply #55 –
I recently reencoded all my FLACs which were encoded with reference libFLAC 1.2.1 20070917 -8 to reference libFLAC 1.3.2 20170101 -8 and overall it saved about 8 GB or 0,35 %

Code: [Select]
before
2.228.270 MB

after
2.220.534 MB

(the data is somewhat not representative because I my last "optimize file layout + minimize file size" for EVERY file is some years back but the embedded cover art usually doesn't get changed ever)

I first started with -8 -ep which gave me about 5x realtime speed which I calculated would have taken a month, so I canceled and switched to -8 (without -ep) which went up to 500x realtime speed (5 yo quad core + HT)

Re: higher compression ratios in FLAC

Reply #56 –
https://xiph.org/flac/changelog.html
    FLAC 1.3.1 (25-Nov-2014)
        - New apodization functions partial_tukey and punchout_tukey for improved compression (Martijn van Beurden).
        - Retuned compression presets to incorporate new apodization functions (Martijn van Beurden).