Compression

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robin67

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Compression
« on: 4 Aug 2015, 11:57 am »
I was just going through some of my flac downloads and noticed some at 0% compression and some 30-60 % compression , I thought when downloading Hi rez files they should be at 0% compression .
I switched awhile back from vinyl to digital and trying to understand this .

The files I downloaded are from Pono , HD Tracks    my question is when downloading HiRez is it normal to get compressed
music ?

ted_b

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Re: Compression
« Reply #1 on: 4 Aug 2015, 01:09 pm »
FLAC is a compressed lossless codec.  The files are compressed for storage and/or download size considerations.  That what FLAC is.  They get decompressed at playback.

robin67

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Re: Compression
« Reply #2 on: 4 Aug 2015, 01:25 pm »
FLAC is a compressed lossless codec.  The files are compressed for storage and/or download size considerations.  That what FLAC is.  They get decompressed at playback.

I have Flac files that show zero compression also , so are you saying compressed vs uncompressed that there should be no sound difference at playback ?

ted_b

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Re: Compression
« Reply #3 on: 4 Aug 2015, 01:42 pm »
Yes, DBPoweramp, for example, has an uncompressed FLAC option.  (Note: that is different from 0 setting, which is low compression).  Net/net, they all (except uncompressed) get decompressed before playback.  Some folks feel that the decompression step uses enough cpu horsepower that it is potentially audible, but FLAC developers and users alike claim lossless is lossless.  When I rip I use uncompressed FLAC; storage is cheap.

You will always find FLAC downloads to have some compression because they want to lighten the load/bandwidth of the download process, let alone their own cloud storage requirements.

robin67

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Re: Compression
« Reply #4 on: 4 Aug 2015, 02:25 pm »
Yes, DBPoweramp, for example, has an uncompressed FLAC option.  (Note: that is different from 0 setting, which is low compression).  Net/net, they all (except uncompressed) get decompressed before playback.  Some folks feel that the decompression step uses enough cpu horsepower that it is potentially audible, but FLAC developers and users alike claim lossless is lossless.  When I rip I use uncompressed FLAC; storage is cheap.

You will always find FLAC downloads to have some compression because they want to lighten the load/bandwidth of the download process, let alone their own cloud storage requirements.

Thanks   :D

robin67

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Re: Compression
« Reply #5 on: 4 Aug 2015, 08:19 pm »
I took the flac file with 34% compression and converted it to uncompressed wav , by doing this do I gain anything ?


robin67

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Re: Compression
« Reply #6 on: 5 Aug 2015, 12:38 pm »
I'm guessing not since you say flac decompresses as it playing with no difference in sound 

barrows

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Re: Compression
« Reply #7 on: 5 Aug 2015, 02:03 pm »
There are those, as Ted mentions above, who believe that de-compressing FLAC audio files during playback can have a deleterious effect on sound quality.  The only way that this is possible is if the additional CPU load causes more noise (RFI) in the serving computer, and if this noise is then able to couple into the DAC, or elsewhere in the audio system chain.
While the claim seems far-fetched at first, there is enough evidence to suggest there is something to this claim, but it is also likely that the level of effect (if at all) is very low, and also system dependent.
In any case, storage is pretty affordable these days (especially in audiophile terms) for complete peace of mind, I store my music in an un-compressed format to avoid any possible sonic penalty, as Ted advises above.
To be sure, there is no problem downloading files in FLAC at all, as it is lossless compression, and once de-compressed, the files are identical to the original.
There are those who suggest that any process done to a music file changes how it sounds, but no actual evidence of this has ever been demonstrated-some of these folks even believe that sending a file through e-mail will change it's sound, even when any analysis shows the file stays "perfect".  I suggest anyone who hears this "problem" best stick with only analog sourced music, as anything digital will be horribly corrupted by all the file transfers and processing done during recording/editing/mastering!