Comparing xdelta and open-vcdiff

[Pointernil]

hi all,

comparing the results (patch sizes created) between xdelta3 and open-
vcdiff
i see xdelta3 creating smaller patches.

As i'm not fully familiarised with the topic and just wanted to know
if that's something caused by systamatic differences between those
two,
or should the patch sizes be expected to be in close range?

[open-vcdiff]

Thanks for using open-vcdiff and xdelta3!

My understanding is that xdelta3 applies a secondary compression
scheme after performing delta encoding. This is controlled by the
options -0, -1, ..., -9 as with gzip.
open-vcdiff does not apply such compression. It is best to apply gzip
(or zlib) to the output of open-vcdiff before transmission or storage,
just as one would do with a .tar file.

Here's a comparison of open-vcdiff and xdelta3 output after producing
a delta for two 30KB text files with similar contents:

Before applying gzip:
open-vcdiff: 9308 bytes
xdelta3: 4755 bytes
xdelta3 -0: 9420 bytes
xdelta3 -9: 4466 bytes

After applying gzip:
open-vcdiff: 4005 bytes
xdelta3: 4248 bytes
xdelta3 -0: 4434 bytes
xdelta3 -9: 4013 bytes

[Pointernil]

Thanks alot for the quick clarification.
I assume this means both conceptually target for comparable patch
sizes.

Turns out I used wrong parameters when trying to disable xdeltas
compression for the comparison. Doh!

Thanks