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Trance Forum Л Л Forum Production & Music Making - .FLAC

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.FLAC

DJ YARU

Started Topics : 9
Posts : 19
Posted : Jan 25, 2005 00:50

Gia sou file mu

Id like to know about Flac format plz. This file is shorter than wav but much better than mp3. Is it a new format? Is it a fake?

Efharisto
yaaammmmasssss

Narcosis
Narcosis

Started Topics : 45
Posts : 618
Posted : Jan 25, 2005 02:02

I personaly dont know friend. but it is interesting. maybe someone knows.

crackerjap

Started Topics : 7
Posts : 46
Posted : Jan 25, 2005 03:14

it compresses the silent parts of the signal.
if you record white noise, the file size will be the same as wav
if you record silence, the file size will be close to 0mb

UIU
IsraTrance Full Member

Started Topics : 88
Posts : 238
Posted : Jan 25, 2005 08:13

Is there a flac player? Cause I could only find a program to decompress it to wav.

Spindrift
Spindrift

Started Topics : 33
Posts : 1560
Posted : Jan 25, 2005 12:39

FLAC stands for Free Lossless Audio Codec.
Basically you get a bit-by-bit copy of the wav with normally around 65% the size.

It's supported by some harware and there is a plugin for winamp for example so you do not need to decompress the files before listening.

Homepage for FLAC:
http://flac.sourceforge.net

Can be hard to find the neccessary downloads there so you can go to this page if you like winamp or nero plugins as well as the decoder:
http://aliveaudio.net/flac.html

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XrTC

Started Topics : 7
Posts : 720
Posted : Jan 26, 2005 19:12

so, if it's true that it compresses the silent parts of the signal, i guess it's not so much of use in psytrance... right?

p.s. dj yaru, your greeks are very nice hehe!

.
Respect is earned, not demanded...
.
http://www.myspace.com/xrtcmusic
.

Spindrift
Spindrift

Started Topics : 33
Posts : 1560
Posted : Jan 26, 2005 19:47

The figure i mentioned, 65%, is for intense and loudly mastered trance, I guess you might get down to 50% on much ambient.

And I am not sure in detail how it works, but I don't think it's strictly correct to say that it compresses the silent parts only.
It might be true that pure white noise will not compress and silence will result in no filesize,
But from what I understand it has not so much to do with the amount of silence as the variation in numbers.

Say you have a sound with amplitude values between 0-9. Over ten samples it might be for example 1 2 4 9 9 9 3 3 3 0
Instead of representing that with ten sign as I did now you could write 1 2 4 39 33 0

Thats 7 signs, ie 70% of filesize, and if you know how you are supposed to interpit it you get the same information as the previous example.

Basically if there is any kind of pattern in the sequence of numbers you can think of ways to reduce the number of signs you need to express it.
White noise have pretty much no pattern, and silence just a straight line of the same numbers hence the differences in compression rate.

Basically thats how numerical compression techniques like zip and flac work if I understood it correctly.

NikC
BeatNik

Started Topics : 40
Posts : 601
Posted : Jan 26, 2005 20:06

well this is what i know:

a pcm-wav file stores a list of numbers (amplitudes) along with a sample rate at the beginning of the file, its easy to store, but incredibly innefficient

aiff. is also lossless but better than wav, as it says (basically) there are a lot of amplitudes value X, now value X takes up 32 bits but if we replace it by "A", that takes up 8 bits so we gain 8 bits of space, and then repeats that kinda idea in a more complex way

flac does this: say you have a 32 bit wave file and lets say it has a quieter (not necessarily silent, but where the peak isn't at 0db) bit in the middle, that quiet bit won't use the full 32bit range...
so we can use a smaller range, say 16bit, but keep the same quality, because the range size/bit is the same.

and then there is non- lossless compression like mp3 whic basically says:
here's a harmonic that you can't hear because it's on top of a fucking massive waveform

hope i'm correct in all this

PEace

Spindrift
Spindrift

Started Topics : 33
Posts : 1560
Posted : Jan 27, 2005 15:29

My example was maybe bad, but in essence we are talking about the same thing.

Using binary numbers a 16 bit signal with less than 50% amplitude would be starting with eight 0's.
So you could of course basically just make the compression routine discard the starting zeros and add them again when decompressing.

I would think though that if you take a full amplitude DC offset signal you would get near 100% compression as well even if the signal would be consisting of only 1's, so it works both ways.
A full amplitude 16 bit signal could of course be represented as 1 bit as long as it's clear that it should be scaled back up 100% amplitude when converted back to 16 bit.

A lossless compression does not really treat the audio as such but rather as a string of numbers.
So it's just about finding patterns in the numerical information so you can reduce the number of bytes you need to represent the number correctly, like with zip compression.

Btw...where did you get that aiff should be compressing the data?...they always seemed to be about the same size as wav to me.

NikC
BeatNik

Started Topics : 40
Posts : 601
Posted : Jan 27, 2005 15:58

@ spindrift...

Yeah we are talking about the same thing!!

i just thought i'd write down what i knew...

about the Aiff. files, that was rather random how i found out, so i'm not sure if its entirely true... I was speaking to a programmer friend of mine about codecs and that was his definition of aiff... still i'm not entirely sure if its right, i've also always thought the files are about the same size... hmm... oh well

Peace

Trance Forum Л Л Forum Production & Music Making - .FLAC