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Topic: Why does 24/44.1 compress less than 16/44.1? (Read 2169 times) previous topic - next topic
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Why does 24/44.1 compress less than 16/44.1?

Just out of curiosity...

I have the Beatles 24 bit remaster set and re-encoded all of the files using FLAC 1.2.1 at the default compression level of 5.  I also have a few of the 16 bit remasters compressed at the same level to compare them to.

Compression levels of the 24 bit files generally range from 21% to 30%, with 25% being about the average.  The 16 bit set ranges from about 36% to 52% compression, with the average around 45%.

I was just wondering why FLAC is unable to achieve similar compression ratios with 24 bit material.  Is it just the math that makes the larger sample size "less compressible" by nature?

Why does 24/44.1 compress less than 16/44.1?

Reply #1
The extra 8 bits are basically filled with noise, and noise is generally incompressible.  So you're compressing the original 16 bit content more or less, then storing 8 bits of uncompressed stuff alongside it, more or less.

Why does 24/44.1 compress less than 16/44.1?

Reply #2
Although I agree with saratoga's answer I have a quick question since I don't have those albums (at least not that exact pressing): Is there any large differences in the stereo image?

I ask since some pressings are mono, close to mono or some other stereo facsimile. Larger differences in L-R channels has a big impact on mid-side encoding efficiency. Another thing if a mono recording was remastered with added stereo reverb it would naturally take more bits to preserve the recording.
"Something bothering you, Mister Spock?"

Why does 24/44.1 compress less than 16/44.1?

Reply #3
The 24-bit and 16-bit versions are identical (other than dither). There are no mastering differences - just the expected differences of taking a 24-bit recording of a 1960s tape and converting it properly to 16-bits.

Read the Amazon.com reviews for a laugh!

FLAC (like every other relevant technology) struggles to losslessly compress random noise by much at all.

Cheers,
David.
P.S. It's almost all stereo.

 
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