[Flac-dev] FLAC 24 bit test results

[Brian Willoughby]

Josh (Green),

Seems like the longest example in your list is a 15-second file.  I  
would like to see the same problem exhibited in a file that is of a  
normal length.  I have been recording full performances lasting  
hours, and flac always compresses the files below 70% of the original  
size.

Another thing to note is that "--best --no-padding" will not create a  
file that is larger than the original.  Perhaps the only reason  
you're seeing the file grow when flac-compressed is that you're  
allowing the default padding to add to the file size.  I am not  
familiar with WavPack, but perhaps it does not add empty padding for  
metadata.

One of the other volunteers looking at this problem produced a 3- 
minute track that was supposed to have the same problem, but it ended  
up compressing quite well ... 58% of the original size.  He's looking  
into why he remembered having problems in the past.

If we can't reproduce this problem with normal-sized songs, then  
perhaps the best solution is to recommend that users simply turn off  
padding if they need to compress extremely short audio samples.

Brian Willoughby
Sound Consulting


On Apr 2, 2007, at 12:02, Josh Green wrote:

Thanks to those who sent in results for the 24 bit FLAC test I created.
Results were received for Windows, Linux, and Intel Mac.  All results
showed the identical poor compression ratio with the given test file.
This indicates that the issue is likely not related to a certain
platform/compiler.  I also tested FLAC with various other options like
integer only and turning off ASM optimizations (to see if the problem
code path could be narrowed down), which did result in different output
data, but the compression was slightly worse.