Topic: Lower bit rate after encoding to FLAC/ALAC?

[df]

Very possible there is already a thread discussing this matter, but I've noticed that after I've bounced my master wav files (recorded in 24/48) and encode to FLAC or ALAC the bit rate is lower by a significant amount.  The WAV files are 2304 kbps (@ 48khz/24 bit) and the FLAC files are 1562 kbps (approximately).  Doesn't this undermine the point of FLAC and ALAC if there is less information and lower quality to any degree?

[dabbler]

"Bit rate" isn't a meaningful determination of quality when it comes to lossless compression.

How are you determining bit rate?  Reading the sox source code, the "Bit Rate" field from soxi output accounts for the file size.  So that shows you how efficiently compressed the file is, but you'll get exactly the same audio you put in when you decompress the FLAC.

[df]

"Bit rate" isn't a meaningful determination of quality when it comes to lossless compression.

How are you determining bit rate?  Reading the sox source code, the "Bit Rate" field from soxi output accounts for the file size.  So that shows you how efficiently compressed the file is, but you'll get exactly the same audio you put in when you decompress the FLAC.

then why are mp3's inferior sound quality at 320 kbps vs 128 kbps etc.?

[dabbler]

MP3 is lossy compression, totally different goals and implementation from lossless formats such as FLAC or ALAC.

[keytohwy]

There are a number of analogies to use, but I'm lazy, so here...

From another site:

Uncompressed audio from standard redbook CD has a fixed bitrate. It is stereo (two channels), 16 bits per sample, 44,100 (44.1 kHz) samples per second.

2 x 16 x 44,100 = 1,411,200 bits per second (bps), or approximately 1411 kbps

But when compressed using FLAC or another lossless codec, the bitrate will be less. A particular track that compresses 30% will have a bitrate of 70% of 1411 kbps

30% compression -> (1 - 0.30) x 1411 = 988 kbps

and so on...

40% compressed -> 847 kbps
50% compressed -> 706 kbps
60% compressed -> 564 kbps
65% compressed -> 494 kbps
70% compressed -> 423 kbps

In my own FLAC library I have files that have compressed as little as 21% and some as much as 76%. So, yes, the bitrate can be expected to vary wildly.


And...
Go to random.org and generate a text file from random characters (10000 strings of 20 characters, using both numbers caps and minuscles) file. That gives you 10000 lines, each of 20 characters. Save it into a .txt file.
Compress it into a .zip file.

Then create a text file consisting of 20000 lines, each of 20 characters, where all characters are space. That is the same size as the previous .txt file.
Compress it into a .zip file.


Both zip files will be unzipped to their respective originals, yet the latter is much smaller. Is that because it is of lesser quality?