[Ardour-Users] Session Archival

Sakari Bergen sakari.bergen at tkk.fi
Mon Jan 19 03:57:19 PST 2009

Gordon JC Pearce MM3YEQ wrote:
> On Fri, 2009-01-16 at 10:00 -0600, Brett Clark wrote:
>> Hash: SHA256
>> I usually tar mine up (with gzip compression) and burn them to CD (or
>> DVD) when im completely done. I haven't analyzed the compression, but I
>> think it gets you around half the size (eg. 8 Gig session down to 4 Gig
>> tar.gz file) which I believe is close to what FLAC can do with the WAV
>> files.  Not to mention that you may also want the session files and
>> everything else in your session (which FLAC doesn't do).
>> Ex: tar -czvf mySession.tar.gz mySession
>> With this method, I could restore the session and do whatever (remix,
>> etc).
> Also, since flac is lossless, you probably have just about as much
> compression by zipping the tarball.  You might get more compression with
> bzip2, at the expense of speed.
> Gordon
Lossless codecs that are made for a special purpose, are always more 
efficient than general purpose compression algorithms. I took a  2 263 
216 B chunk from a commercially mastered piece of music and ran it 
through flac and bzip2:
- FLAC ended up being 1 378 323 B, with a ratio of 0,61
- bzip2 was 2 019 557, with a ratio of 0,89
- You can probably get even better results with less complex signals

However, the problem with FLAC is that it doesn't support encoding 
floating point samples, which is Ardour's (and Jack's) native format. 
Thus it will not be truly lossless. Wavpack on the other hand can encode 
floats losslessly, and is thus better suited for compressing Ardour 
source files.

To further reduce the size of the archive, you can remove the peakfiles 
from from the peaks directory. These will be recreated once you re-open 
the session.


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