PDA

View Full Version : FLAC question



Ken Veasey
2004-03-26, 16:53
Bit of a basic question, but here goes. I'm just venturing down the
path of converting to flac. Using Windows I am extracting my CDs using
Exact Audio Copy and in a separate operation converting to flac using
FLAC Frontend (I like the comfort of a GUI). The first couple of CDs I
have done are coming in at just over 55% of the original wave size.

Does this sound correct?

I note that there is a setting in FLAC Frontend called "Encoding
Options" with a level going from 0 to 8. Having tried the two extremes
there is not a significant difference in the resulting files but set
at 0 the encoding is very quick and I assume therefore something may
get lost. What's the suggested approach?

Ken Veasey

Jason Holtzapple
2004-03-26, 21:27
Ken Veasey wrote:
> Bit of a basic question, but here goes. I'm just venturing down the
> path of converting to flac. Using Windows I am extracting my CDs using
> Exact Audio Copy and in a separate operation converting to flac using
> FLAC Frontend (I like the comfort of a GUI). The first couple of CDs I
> have done are coming in at just over 55% of the original wave size.
>
> Does this sound correct?

Yes.

> I note that there is a setting in FLAC Frontend called "Encoding
> Options" with a level going from 0 to 8. Having tried the two extremes
> there is not a significant difference in the resulting files but set
> at 0 the encoding is very quick and I assume therefore something may
> get lost. What's the suggested approach?
>
> Ken Veasey

FLAC will use about the same amount of CPU time to decode
regardless of the encoding settings - so generally you should
use a higher setting. I recommend 8 or 6. There is a huge
difference in encode time with 8 over 6 with little space
savings. I use 6 because I have a relatively slow processor
in my encoding machine. If 8 encodes in an acceptable amount
of time for you use that.

--Jason

Pat Farrell
2004-03-26, 22:26
At 11:27 PM 3/26/2004, Jason Holtzapple wrote:
>Ken Veasey wrote:
>>have done are coming in at just over 55% of the original wave size.
>>Does this sound correct?
>Yes.

As Ken sez, yes, that it about right.

I see anywhere from 40% to 60% depending on the song,
or phase of the moon. I have no idea what really causes
the differences, there doesn't seem to be any
obvious correlation to music type, genre, tempo,
etc.

>>Options" with a level going from 0 to 8. Having tried the two extremes
>>there is not a significant difference in the resulting files but set
>>at 0 the encoding is very quick and I assume therefore something may
>>get lost. What's the suggested approach?
>
>FLAC will use about the same amount of CPU time to decode
>regardless of the encoding settings - so generally you should
>use a higher setting.

This is a critical design point of Flac.
The decompression/decoding is designed to be fast
and easy. The compression/encoding is very resource
intensive.

This is normally _fine_, because you only encode a song once
but play it many times.


> I use 6 because I have a relatively slow processor
>in my encoding machine. If 8 encodes in an acceptable amount
>of time for you use that.

I use 8 on an old slow processor, and let it compress overnight.

I have not seen much file size difference, and since Flac is lossless,
there is not supposed to be any data or quality difference.
The only difference is file size and how long it takes to
compress.

Realistically, disks come in large granularity sizes. The difference
between a collection taking 180GB and one taking 199GB is nothing,
as you will probably use a 200GB disk anyway.

By the above logic, my use of "8" is probably not justified by
engineering, but the computer was going to be running all night
anyway, so having it compressing with Flac is at least
a useful waste of electricity.

Pat