[Ffmpeg-devel] SVN dump

[Eduardo Morras]

At 13:00 15/04/2007, you wrote:

>Simple, svn-dump dumps the files and revisions in full form. No diffs
>or anything.
>The diffs could be considered form of compression (redundancy
>removal), and compressing compressed material usually doesn't give
>good results.
>
>My guess is that lrz uses quite big search buffer and that allows
>finding the revisions of the same files. gzip uses something like 64kb
>(i think compressed) and bzip2 can have up to 1MB (source data). Well,
>they use different algorithms but still.

lrz uses a mix of compressors, lzma ( www.7-zip.org for details) it's LZ77 with huge window (64K to 128M) and arithmethic coding,; rzip a BWT and lzo uses LZ77 only.
gzip uses LZ77 32K window and huffman. Actually there is a deflate64 spec with 64Kb window but gzip don't use it.
bzip2 uses 900K BWT and huffman.

HTH