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In Reply to: RE: Best format to store music files posted by fmak on June 10, 2007 at 01:36:31
>I am suspicious of FLAC even at 24/96 played backl on Foobar. HF seems to have an unwelcome emphasis.
>Any form of compression entails the use of a statistical model on how to shoten certain types of audio informtaion, and an algorithm ecexecuted to recover the information for playback.
FLAC compressor is lossless, it means that converting a wav file into a flac and bringing it back to wav will give you a bitwise exact copy of the original wav file (i've tested it today, it gives back a wav file with the exact CRC checksum), so i can't figure out how a lossless codec could even alter emphasis or dynamic response.
Lossless codecs (such as FLAC) absolutely don't use statistical or psychoacoustic models to achieve compression (rather than lossy such as mp3, wma ...). The work on the raw byte data of wav files in a similar way of zip(or similar) compressions.
Today i've spent some time to write down an article on my site. It contains also a guide to configure EAC to directly rip cd into flac files.
I hope it would be useful :)
http://www.primianotucci.com/go/flac
Primiano Tucci
(yep, I'm the son of the thread poster, of course ;-) )
Follow Ups:
You need to read up on FLAC!
its a pretty simple test
FLAC compressor is lossless, it means that converting a wav file into a flac and bringing it back to wav will give you a bitwise exact copy of the original wav file (i've tested it today, it gives back a wav file with the exact CRC checksum), so i can't figure out how a lossless codec could even alter emphasis or dynamic response.
I don't think that anyone is arguing that Flac isn't lossless, just that the process of "unzipping it" during playback can affect the sound. Several posters have heard differences between identical files.
This all may depend on the computer involved and extra things going on like use of crossovers, room correction, upsampling.
Do a search for posts from Christine Tham...she has some posts that give some plausible explanations as to why differences are heard.
I've just done a little test.
Using an intel P4 2.4 ghz Prescott cpu the flac decoder takes about 5 seconds to fully decode a 3 minutes flac file to wav.
Now, it actually depends how the player works... it could decode the flac to wav, and then play the wav file, or it could decode and play the flac wav on the fly (if you use the directshow filter the decode and play process is surely done on the fly).
However, doing a simple calculation based on empiric tests, it seems that the flac decoding process takes about 3% of cpu bandwidth (5s to decode 180s of data= 2,7% of real time cpu usage).
Sincerelly I find really hard to believe that an additional 3% could affect resulting sound
One of the great aspects of digital computating is that the response you get is discrete: you get the output waveform,or you lack it, but you can't get a degraded waferorm.
So, in my point of view, the only way (or better the main way) to compromise sound quality is falling in underrun of sound buffers (so you should hears gaps in sound).
In order to have a buffer underrun the cpu must be under severe load averages (and i don't think it's the case of flac decoding).
Howver this argument is really interesting me... as i'll get a bounch of free time i'm curious to try a file by file "Wav vs flac human test" ...i'll let you know my subjective impressions ;-)
Primiano Tucci
What you have done has no bearing on the sound or the accurracy of model or reconstruction
Using crossovers and upsampling on my 1ghz dedicated machine, I can tell you that on occasion I have done combinations particularly upsampling that have maxed out the processor, and made the sound behave like a 45 run at 33 or slower.
3% can make a difference for this pc, and from what you are saying, it is 3 % on your more than twice as fast pc or more than 6% on mine slow one.
let us know how your tests go. Others have heard a difference and I wish I had the spare time that you have to test this myself.
having gone with wav, it is pretty acedemic from me at least.
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